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Research ArticleRare Earths in Geological Formations of Central Region ofthe Dniester River Basin Republic of Moldova
Aurelia Popuiac
State University of Moldova 603 Gh Asachi Street 2028 Chisinau Moldova
Correspondence should be addressed to Aurelia Popuiac apopuiacgmailcom
Received 25 September 2014 Accepted 16 November 2014
Academic Editor Giovanni Martinelli
Copyright copy 2015 Aurelia Popuiac This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
In the different varieties of crystalline basement of Archean and Proterozoic age and in Vendian (Ediacaran) basal layers of platformcoverture in the Central Basin of the Dniester River were found relatively high concentrations of Lanthanum Cerium YttriumYtterbium and Scandium Because the petrographic formations which are genetic associated with RE elements in Dniester regionare absent the origin of these elements is unclear At the same time in the geological mapping it was detect that geochemicalaureoles of REE found in the northern region of Republic of Moldova are generated by accessory minerals monazite and zirconpresent in the rock of basement platform and fragments of crystalline rock in the composition of terrigenous formations from basallevels of sedimentary coverture Probably mentioned minerals are brought fromUkrainian Crystalline Shield regions in which arespread varieties of granitic rocks and alkaline pegmatite It is not excluded that in these basal layers in the sedimentogenes processesand differentiation of detrital material to be formed the mechanic aureoles rich in monazite and zircon which in turn can formsignificant concentrations of rare earths To solve the perspective problem of detection of industrial mineral accumulations of REin the central region of the Dniester River basin it is necessary to conduct within this area detailed geological and geochemicalresearch
1 Introduction
During the years 1982ndash1992 several special geologicalresearches were carried out in the north-eastern part of theRepublic of Moldova with the purpose of determining themetallogenetic features in this area The central basin ofthe Dniester River has already been considered perspectivein terms of detecting mineralizations of the radioactiveelements rare metals iron zinc lead and barite includingthe rare earths In many varieties of crystalline basementrocks and basal layers of sedimentary cover were found rela-tively high concentrations of rare earths (RE)mdashLanthanumCerium Yttrium Ytterbium and Scandium
At the time of undertaking the geological mappingworks at scale 1 200000 (1947ndash1952) in the whole Europeanterritory of ex-USSR sedimentary formations in the northernpart between the rivers Dniester and Prut had already beendifferentiated and in outcrops of the river Dniesterrsquos bed(village Cosauti Soroca) had been started first researches of
crystalline rocks in cropping At the same time with geo-logical mapping were effectuated works of prospecting andexploring useful mineral deposits Information on previousgeological works is included in the publication ldquoGeology ofUSSR Vol XLVrdquo [1]
In terms of methodology all preliminary prospectingworks were based on drilling carried out in areas ofgravitational and magnetic anomalies considered by manyresearchers anomalies generated by disturbed geologicalbodies which may contain useful mineral deposits In mostcases the drillings crossed the rocks that contained quitesmall concentrations of useful components situated nearbythe sensitivity threshold of chemical analyses Thereforethe undertaking of some detailed geological works in thespecified region had not been sufficiently argued
Geological mapping of Precambrian formations of thecrystalline basement and the basal layer of sedimentarycover effectuated on a territory with a relatively limited area(Figure 1) were continued by a group of researchers from the
Hindawi Publishing CorporationAdvances in GeologyVolume 2015 Article ID 713282 13 pageshttpdxdoiorg1011552015713282
2 Advances in Geology
IV
IV
I
I
C
E B
II
IIIII
III
D
1
2
3
4
5
6
7
A
minus600
minus2400
minus400minus500
minus600
minus2400
minus400
minus200
minus800
minus1000
minus1200
minus1400
minus1600
minus1800
minus2200
minus2600
minus350
minus450
minus400
Figure 1 Schematicmap of geological structure of the Republic ofMoldova [1] 1mdashisohypses of Precambrian crystalline basement constructedon basis of drillings 2mdashisohypses of Precambrian crystalline basement constructed on basis of geophysical prospecting 3mdashisohypses ofHercynian crystalline basement constructed on basis of drillings 4mdashzone of maximal gravitational gradients 5mdashtectonic disjunctions6mdashPrecambrian crystalline rocks 7mdashMetamorphosed rocks of early Paleozoic age I-I Dniester Fault II-II Ciadar-Lunga Fault III-IIICahul-Ismail Fault IV-IV Ciuhur Fault AmdashUkrainian Crystalline Shield region Bmdashslope of Southwestern East European Platform CmdashThe Predobrogean Depression Dmdashnorth-west region of the Dobrogea Orogen EmdashSouth West region of the Precarpathian Depression
ex-Geological Department of MSSR (now Agency of Geo-logical Mineral Resources ofMoldovamdashAGRM) A ZaharovV Sergheev V Ciobotaru E Hiora G Fedorenko and soforth Because of changes that followed the proclamation ofthe Independence of the Republic of Moldova the researcheswhich had to be executed in a more detailed way were notrun to a successful end To some extent the geological dataand the issues addressed in this chapter are unique becausewe are not sure that in the near future in Dniester region suchworks will be undertaken
Study of the composition and origin of geological forma-tions of Archean-Proterozoic basement allowed following theevolution of substance from the earth crust beginning fromthe moment of accumulation until hypergen modificationstages of rocks in conditions of the platform
Both in the process of geological study in the field andin the process of elaborating this chapter all correspondingmaterials edited or available in AGRM funds have beenexamined with great attention
Some rather general concepts about the geological struc-ture of crystalline formations covered by much youngercomplex sedimentary layers were elaborated based on datafrom drillings executed in different years with the pur-pose of geological mapping geological and hydrogeologicalprospections On the territory between the rivers Dniesterand Prut during about four decades were executed a largenumber of drillings majority of which also crossed the base-ment rocks in the northern part of country As a rule drillingswere undertaken only for research purposes of sedimentaryrocks and because of this the opening depths of Archean andProterozoic rocks of crystalline formations ranged betweenabout 20 and 50meters Having at disposition a great numberof cores it was possible to research only composition ofcrystalline rocks from the surface of Precambrian basementThere had been several attempts on the basis of the drillingand geophysical prospecting to elaborate the geological mapsof some portions of the crystalline basement surface [2 3]and the layers of sedimentary rocks of the lower levels of
Advances in Geology 3
platform cover [4] but all such geological deductions haveproved to be arbitrary often subjective and presented more apersonal vision of researchers on the geology of earth crustin this area [5] Also rather approximately had been executedthe geological prospectings in order to solve the perspectiveof detection in the mentioned region of some significantaccumulation of rare earth elements [6]
The proposed study is one of a synthesis of geologicalresults performed by a group of researchers who have workedtogether beginning with the design field research andlaboratory analyses and ending with the generalization ofobtained data In this regard the author presents not onlythe geological vision of this group but also his own conceptconcerning the specificity of rare earths in the region ofMoldovan segment of Dniester basin
2 General Suggestions Concerningthe Geological Structure of the Territory ofthe Republic of Moldova
On the territory of the Republic ofMoldova are distinguishedseveral fragments of some regional structures which in termsof tectonic and geological evolution are different from eachother in a highlighted manner [8]
About two thirds of the territory of the republic falls in asegment of southwest pericratonic zone of the East EuropeanPlatform called by Moldavian and Ukrainian geologists theldquoMoldavian Platerdquo (Figure 1)
A part of south-eastern region is occupied by a fragmentof the Dobrogea Orogen which endorses the typical featuresof a young platform Constituted in late Paleozoic it is con-sidered an epi-Hercynian platform Crystalline basement isconstituted by metamorphosed rocks in lower metamorphicfaces and igneous intrusions and sedimentary cover about500 meters thick is formed by Mesozoic-Cainozoic age strataplaced almost parallel
Another regional structuremdashPredobrogean Depressionwhich extends to the northwest in Romaniamdashis seen bysome researchers [9] as a component part of the EastEuropean Platform At the same time the geological evolutionof this structure and tectonic processes which manifestedthemselves in the Paleozoic and especially in the earlyMesozoic allow considering the Predobrogean Depression anindependent structure with specific geological and structuralfeatures
In the northern and north-eastern regions of the Republicof Moldova (marked area in Figure 1) we can highlightthree geological-structural units crystalline basement sed-imentary cover composed of diverse rocks and Pliocene-Pleistocene formations These three geological-structuralunits in terms of age origin and composition are differentfrom each to other in a cardinal way Due to shallow depthsup to crystalline rocks of the basement and mineralizationwhich contain elements of rare earths discovered in the basallayers of sedimentary cover the central region of the DniesterRiver basin has always made up a remarkable object of studyfor geological research
3 The Petrographic Specificity ofthe Crystalline Basement Rocks
The principle of differentiation of crystalline rocks inmost cases Archean or of early Proterozoic age situatedin the basement composition was and remains a subjectof permanent discussion In geochronological-stratigraphicterms the most appropriate methodological principle in thegeological study of the south-western slope of the EastEuropean Platform is the correlation of ultrametamorphosedcrystalline formations within a regional or local geotectonicunit Basement rocks in the area reflect all the specificfeatures of geological processes that led to the formation ofthe south-western slope of the Ukrainian Crystalline Shieldwhich is situated to the north of the Dniester Faultmdashthemost important geotectonic element from the mentionedregion (Figure 1) Crystalline basement is an agglomeratecomposed of metamorphic ultrametamorphic magmaticand metasomatic rocks of different agesmdashearly Archeanand early Proterozoic In general crystalline formations arepresented in an extremely complicated way but at the sametime there are some distinguishing features that differentiatethis portion of the earth crust from other neighbouring areasAnalyzing the magmatic and ultrametamorphic processeswhich occurred in the Precambrian of Ukrainian CrystallineShield Archean and Proterozoic rocks and can be system-atized in specific formations that differ from each otherby petrographic varieties and physicochemical conditions oftheir formation [10] gneisses and crystalline schists (earlyArchean age) enderbites plagiomigmatites plagiogranites(formed as a result of anatexis processes at the geochrono-logical limit of later Archeanndashearly Proterozoic) alaskitesleucogranites (early Proterozoic age of palingenesis origin)mdashTable 1 Having a predominantly granitic composition thesevarieties of rocks differ from each other only in the auxiliaryindex (accessory mineralizations presence of geochemicalaureoles and geophysical anomalies) It should bementionedthat in the composition of these rocks with rare exceptionspredominate plagioclases (oligoclase-andesine) and almost inall lithological varieties often in significant quantities is alsopresented hypersthene
Is typical associations of accessory minerals consti-tuted from zircon monazite garnet apatite magnetiteand ilmenite which with some exceptions are presentalmost in all petrology varieties It is significant that in theoldest rocks of the gneisses formation (dominate biotite-amphibole-hypersthene plagiogneisses) of early Archean agemonazitemdashone of the most important minerals in geologicalformations of the basement from area that contains rareearthsmdashwas found only occasionally and zircon is found inform of small isolated grains in relatively small quantitiesin almost all varieties of gneisses and crystalline schistsAs an accessory mineral monazite frequently occurs inmineralogical composition of the ultrametamorphic varietiesof enderbite and alaskite formations
We would like to pay attention to the fact the major-ity of zircon grains which are in ultrametamorphic rockscomposition have round forms with melting traces of the
4 Advances in Geology
Table1Precam
briancrystalline
form
ations
inthes
outh-w
estregionof
theU
krainian
Crystalline
Shieldandaccessorym
ineralconcentrations
which
containelem
entsof
REgrou
p(C
entral
region
oftheD
niesterR
iver
basin
)
Num
ber
Form
ations
andcomplexes
ofrockslowast
Agelowast
106years
Petro
graphicv
arietie
sMineralogicalcompo
sition
Accessoriesm
inerals
1Ch
arno
ckitesa
ndgranites
form
ation
Lowe
rProterozoic
(200
0ndash2200)
Alaskite
Quartz(20ndash4
0)
Microcline
(35ndash70)
Plagioclasemdash
Pl20ndash25(5ndash35
)Biotite
(0ndash5)
Zircon
(5ndash2
00gt)
Mon
azite
(30ndash
250g
t)Magnetite(9ndash
4009
gt)
Apatite
(sim14gt)
Garnet(7ndash17gt)
2Leucogranite
Quartz(20ndash35
)Microcline
(5ndash35
)Plagioclasemdash
Pl20ndash25(30ndash
35)
Magnetite(sim20
gt)
Zircon
(656
gt)
Mon
azite
(1270g
t)Ap
atite
(sim20
gt)
3Plagiogranitesa
ndtonalities
form
ation
Upp
erArcheanndashL
ower
Proterozoic
(2550ndash
2800)
Plagiomigmatite
Quartz(20ndash30
)Plagioclasemdash
Pl25ndash30(60ndash
80)
Biotite
(lt10)
Microcline
(lt5
)
Apatitesim
Mon
azite
(12ndash
211g
t)Zircon
(12ndash
190g
t)Garnet(23ndash183
gt)
4Plagiogranite
Quartz(20ndash50
)Plagioclasemdash
Pl25ndash30(35ndash70)
Pyroxene
(5ndash15
)Biotitesim
Microclinesim
Apatite
(10ndash
40gt)
Zircon
(sim10
gt)
Mon
azitesim
Magnetite(200g
t)Ilm
enite
(1430
gt)
5En
derbitesformation
Upp
erArchean
(2850ndash
3150)
Enderbite
Quartz(20ndash30
)Plagioclasemdash
Pl25(50ndash
80)
Pyroxene
mon
oclin
ic(5ndash15
)Hypersth
ene(5ndash20)
Biotite
(lt5
)Microclinesim
Apatite
(228ndash1080g
t)Zircon
(20ndash
30gt)
Mon
azitesim
Ilmenite
(sim658g
t)Magnetite
(3317ndash7550
gt)
6Th
ecom
plex
ofmetam
orph
icrocks
Lower
Archean
(3300ndash
3750)
Biotite-pyroxeneP
lagiogneiss
Quartz(10ndash30
)Plagioclasemdash
Pl30(40ndash
60)
Pyroxene
mon
oclin
ic(5-4)
Hypersth
ene(lt10)
Biotite
(10ndash
15)
Microcline
(lt10)
Apatite
(17ndash680g
t)Zircon
(8ndash6
0)gt
Ilmenite
(sim1000
gt)
Magnetite
(24ndash
1348
gt)
7Biotite-amph
ibole-pyroxene-
plagiocla
sewith
magnetite
crystalline
schist
Plagioclasemdash
Pl30(10ndash
70)
Pyroxene
mon
oclin
ic(sim15)
Hornb
lend
e(sim25)
Biotite
(sim20)
Quartz(lt5
)
Magnetite(5ndash10gt)
Apatite
(sim170g
t)Zircon
(sim20
0gt)
lowast
Accordingto
thes
tratigraph
icschemee
labo
ratedby
theR
egionalStratigraph
icCom
mittee
from
Ukraine1984
Advances in Geology 5
external zones Perhaps because of higher refractory prop-erties this accessory mineral passed from older geologicalformations in the younger ones without essential changesthat are imposed by anatexis and palingenetic processesProbably it also refers to monazite present in the samevarieties of rocks It produces the impression that multipleacts of progressive metamorphism ultrametamorphism andretrograde metamorphism that took place during an enor-mous period of geological time and modified in a cardinalway all petrologic varieties of the platform basement anddid not influence the redistribution in underground spaceof zircon and monazite The above-presented affirmationis supported by geochronological research data achievedthrough the radiological methods by Ukrainian geologists Inthe regions of Ukrainian Crystalline Shield slopemdashadjacentarea of Dniester River basin monazite and zircon in rockcomposition from formations mentioned above practicallyhave one and the same Archean age [11]
Many authors link the formation of concentrations ofRE elements in the Dniester region with the presence ofaccessory monazite and zircon which are present in compo-sition of different petrologic and lithological varieties of lateArchean early Proterozoic and Vendian ages [5] Remarkingthe high correlation coefficient between zircon and monazite(120588 = 073) and satisfactory degree of correlation (120578 =86 gt 3) we can assume that these two minerals interms of geology are syngenetic and probably as accessoryminerals were formed at the same time in one and the samepetrological formation At the same time we would liketo emphasize that monazite in the complex composition ofmetamorphic rocks of early Archaic age practically was notfound On the basis of the data from previous mineralogicaland geochemical researches it was determined that monaziteweight in geochemical aureoles formation (RE-elements) ismuch higher than that of zircon [12] We would like to notethat between crystalline and terrigenous formations in thisarea in quite small quantities can also be found othermineralscontaining rare earths (xenotime and allanite) [10]
Most of rare earth minerals including zircon and mon-azite are constituents of granite and nepheline-syenite peg-matites There are known endogenous deposits of the rareearths which are in geological-genetic relations with alkalinegranites intrusive alkaline ultrabasic rocks syenites (rich inpyrochlore) and pneumatolytic hydrothermal formations Ifwe examine the mineralogical compositions of the meta-morphic and ultrametamorphic rocks varieties in the centralregion of the Dniester River basin we will observe that inthese types of crystalline rocks in no way can form parage-netic associations with minerals which contain rare earths[9] It is possible that accessory mineralization of zircon andmonazite has no directly bearing to the origin of formationsfrom this area but can be part of some blocks of the earthrsquoscrust from neighboring regions For example in differentregions of the Ukrainian Crystalline Shield (Jitomir Vinita)in alkaline granitic and pegmatite rocks with monazite andzircon were found significant concentrations of RE elements(Lanthanum Cerium and Neodymium) [13]
From the above-said results that the issue of mineralsrsquoorigin (especially of zircon andmonazite) which contain rare
earths found in different varieties of crystalline rocks in thesouth-western East European Platform remains open
In terms of fundamental geotectonic concepts the oldestparts of the continental earth crustmdashcrystalline shieldsmdashduring the geologic time underwent several cardinal tectonicmodifications [14] Therefore it is presumed that in thetectonic cycle of theWhite Sea (Archean) the manifestationswhich are well observed in the Baltic Crystalline Shieldformations ended with intensive folding metamorphosingand profound granitization phenomena For correspondinggeological epoch is characteristic the formation of somegranite-gneiss domes delimited in the initial phase by linearzones consisting of volcanogenic-sedimentary rocks Atpresent these linear areas are transformed into relatively nar-row synclinorium formed of profoundly modified rocks indifferent metamorphic facies As a result of the epi-Archeantectonic processes (until early Proterozoic) we can assumethat in such synclinorium took place several epeirogenicmovements of crystalline basement concomitantly accom-panied by various destructive processes Consequently incertain places emerged aulacogens delimited by lineamentswithin which are found many remains of Archean blocksand areas with well-pronounced progressive and retrogrademetamorphism manifestations A similar structure could bethe Dniester Fault which de facto represents a segmentof Podolian Tectonic Faults Zone [15] and which delimitsin the south-western part another crystalline shield of EastEuropean PlatformmdashUkrainian Crystalline Shield Tectonicphenomena of early Proterozoic period ended with theconsolidation of the crystalline basement from region Insubsequent geological periods the tectonic activity graduallyreduced tominimum introducing in theDniester-Prut inter-fluves region only some structural changes genetically linkedto the evolution of Dniester Fault For example in Ripheanaround 950 million years along the Podolian Tectonic FaultsZone in a relatively weak process of continental riftogenesisoccurred alkaline lava flows in the result of which lenticularbodies of diabases were formed
Manifestations of effusive or intrusive magmatism inArchean-early Proterozoic in the central region of the Dni-ester River basin have not been determined It is possible thatultrametamorphic processes that took place in this regionin late Archean-early Proterozoic probably ldquoretouchedrdquo com-pletely initial igneous rocks in the area Consequently we cansay that zircon and monazite in the initial stages of geologic-structural formation of pericratonic region of south-westernpart of East European Platformwere already formed and werepart of the composition of pre-rocks
As mentioned above most endogenous deposits of REare genetically related either with alkaline granites intrusionsor alkaline typical intrusions Examining the contribution ofmagmatism in the evolution of earth crust it is determinedthat the alkaline magmatism events began about 25ndash27billion years ago and in an intensive way developed inPhanerozoic and arrived to maximal action in the MesozoicIn general alkaline rocks older than 27 billion years in theearth crust formations have not been found [16]Thus it maybe deduced that the origin of zircon and monazite detectedin geological formations in Dniester region in no way can be
6 Advances in Geology
linked with alkaline intrusions which may have been formedin the Ukrainian Crystalline Shield
It is obvious that theseminerals were formed however in amagmatic process unexplained so far by geologists interestedin the rare earths in the area and the issue of RE origin incomposition of metamorphic and ultrametamorphic rocksof the crystalline basement in the south-western part ofEast European Platform requires a serious investigation to besolved
There exist industrial concentrations of REminerals bothof endogenous type and metamorfogenic one Rare earthdeposits related tometamorphic formations are characterizedby relatively homogeneous distribution of RE elements onareas of significant extension and are presented in generallyby migmatites gneiss and metamorphosed conglomerateswith monazite of other origin It is not excluded that inthe geological formations of the crystalline basement arepresent accumulations of monazite (and zircon) located inplagiomigmatites and leucogranites which have a rather largedistribution in the Dniester region
4 Sedimentary Formations andDetection Premises of Concentrations ofRare Earths Elements
41 The Types of Hypergen Deposits of Rare Earths ElementsRare earths minerals of exogenous origin until now are notknown At the same time most rare earth deposits exploitedat present are of exogenous type
According to systematization of useful mineral depositstypes [17] hypergen deposits of RE are grouped into threetypes
(1) residual which are formed as a result of alterationof granite syenite nepheline-syenite rocks rich inmonazite sphene pyrochlore thorianite cerianiteand formation in erosion crust of a zone rich with REof cerium subgroup Nb Zr Th and Y
(2) sedimentary-detrital (a) alluvial lands formed fromconcentrations of stable minerals in hypergen zonesuch as monazite ilmenorutile zircon uranothorite(b) eluvium-adobe lands with high concentrationsof xenotime pyrochlore fergusonite thorite and (c)mineral lands of coastal areas consisting of significantaccumulations of monazite ilmenite rutile and zir-con
(3) sedimentary and sedimentary-biogenic (a) phospho-rites (b) sands rich in REminerals (c) shales and (d)fossil reminiscences
Referring to the territory in northern and north-eastern partof Republic of Moldova in the basal layers of sedimentarycover may be present the RE deposits such as detritalsediments This confirms the results of recent geological-geochemical researches carried out in the last decades of thelast century [7 18]
In hypergen areamonazite is a quite stable mineral Beingresistant to the action of exogenous agents it is not broken
down and in the following way in rubbly grains is keptvery long periods of geological timeTherefore the monazitepresent in crystalline rocks of Archean and early Proterozoicage is also found in sedimentary rocks of platform cover in thecentral region of the Dniester River basin Since the specificweight of monazite is quite high (exceeding 50 gcm3) inthe erosion process of rocks with accessory monazite andfurther sedimentogenesis of disintegrated material often areformed mechanical aureoles of this mineral Therefore it isexplained that the monazite in detrital sedimentary layersmay be present in concentrations much higher than itsconcentrations in the syngenetic rocks
For example in a drilling for geological mapping dugin the south of the marked territory in Figure 1 has beendetected a geochemical anomaly with maximum concentra-tions of lanthanum (01) and cerium (008) generated bymonazite the concentration of which in basal layers of thesedimentary cover varies between 05 and 218 gt [10]
In a similar process are also formed the mechanicalaureoles of zircon
Sedimentary cover in central region of the DniesterRiver basin is made up of several complex beds placedalmost horizontally In terms of geochronology of lithologicalcomposition of sedimentation conditions and diageneticprocesses in slope cover of southwestern part of theEast Euro-pean Platform are identified four formations and sedimentaryrock complexes Vendian Formation Ordovician-Silurianstratigraphic Complex Cretaceous Formation and NeogeneFormation (note currently in many countries the name ofstratigraphic unit Vendian is replaced with Ediacaran butin Republic of Moldova so far remain the same names ofstratigraphic units used in Russia)
Ordovician-Silurian beds consisting prevailingly oflimestone-dolomite varieties limestone-siliceous rocks ofCretaceous and diversity of limestone sand and clay varietiesof Neogene age in terms of the problem approached in thischapter unlike the Vendian basal layers of sedimentarycover do not present any practical interest
By direct comparison it was demonstrated that thegeological section of Podolian Vendian is stratotype almostfor all formations of this age opened in different regionsof the East European Platform Thus Vendian age layerssituated in natural cropping or crossed by drilling in the northand north-eastern zone of Republic of Moldova presenta southeastern fragment of Podolian Vendian and in anatural way without assumptions the stratigraphic scheme ofUkrainian geologists can also be applied in the Dniester riverbasin conditions For a rather complete documentation aboutVendian Formation in the region we make reference to aquite ample synthesis work prepared by Ukrainian geologistsforTheThird International Symposium on Cambrian System(Kiev 1990) [19]
42 Camenka Formation Directly on the surface of crys-talline basement are laid-down in the deposit the layersof Camenka Formation constituted of basal conglomeratesand diabases probably of Riphean age The formation body(average thickness about 20 meters) has a lenticular-flat
Advances in Geology 7
The distribution area of Camenka formation
Central region of the Dniester River basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of crystalline basement surface (m)Isopachites of Camenka formation (m)
0 10 20
(km) minus280
minus240
minus160
20
40minus140minus260
minus200
minus180
minus160
minus80
minus80
60
minus60
minus200
minus100minus140 1
0
10
10
10
10
10
20
20
20
20
20
20
20
20
20
20
minus40
minus20
minus20
0
30
0
0
30
30
80
Figure 2 The distribution area of Camenka Formation in the central region of the Dniester River basin [13]
aspect is relatively narrow (8ndash10 kilometers in cross section)is oriented in a north-western direction and covers thelinear-depressive zone of Dniester Fault (Figure 2) We canassume that the centers of lenticular forms coincide withchannels throughwhich on the earth surface poured lavawithalkaline composition specific for early stages of continentalriftogenesisThe phenomenon took place in later Proterozoicin one of the last phases of tectonic activity in south-westernareas of the East European Platform
Camenka Formation consists of diabases and a basal layerof microconglomerates and conglomerates (Soroca Beds)
Lithological varieties of Soroca in the spread region ofFormation Camenka do not present an integral structuralunit Firstly these lithological varieties are in deposits just inthe spread zone of diabases and only in someplaces vulcanitesof Camenka Formation are laid-down directly in depositon the surface of crystalline basement Perhaps Sorocabasal beds in the mentioned region had had a much largespread but because of denudation processes were preservedonly under diabases Thickness of Soroca Beds crossed bydrilling mapping varies from 05 to 35 meters Rocks aredistinguished by their mineralogical composition and areformed from an unselected rubbly material conglomeratesconglomerate-breccias microconglomerates (predominant)coarse-grained sandstones and arkose sandstones (rarely)
The rubbly material is presented by slightly rounded grainsof crystalline basement rocksmdashquartzite potash feldsparand biotite scales cemented with a brown argilitic materialCement volume typically exceeds 50 by volume In thefollowing way most of Soroca Bedsrsquo rocks differ by theirspecific brown color
Arkose sandstones and microconglomerates that can befound in the composition of the basal layers of Camenka For-mation are massive rocks hard of gray-green or pink-graycolor have sabulous structures and consist of plagioclase (upto 50ndash60) potash feldspar (up to 15) quartz (25 to 35)cement and grains of basement rocks
In clastic material are prevalent semirounded or ruggedforms and grainsrsquo sizes range from 10ndash15 millimeters(microconglomerates) 10ndash01 millimeters (sandstones)01 millimeters (sandy mudstones) Cement has a highporosity and has a kaolin-hydromicaceous kaolin-chlorite-hydromicaceous or kaolin composition
From accessory minerals are present small grains ofgarnet zircon monazite apatite and titanomagnetite
The rocks of Soroca Beds have a specific radioactivity rel-atively high (30ndash35 micronshour) imposed by the presenceof isomorphic thorium in the monazite composition
Based on geochemical investigations of Sorocamicrocon-glomerate were found relatively high concentrations of La
8 Advances in Geology
0 10 20
(km)
The morfostructure of Vendian formation
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isopachites of Vendian layers (m)Isohypses of upper limit of the Vendian formation (m)
minus80
minus60
minus40
minus20
minus20
0
0
0
20
20
20
20
40
40
40
40
60
60
60
60
80
80
80
80
100
100
100
120
120
120
140
140
140
160
160
160
180
180
180
180
180
200
200
200
200
200
200
220
220
220
220
220
240
240
240
240
240
260
260
260
280
280
280300
Figure 3 The morphostructure of Vendian Formation in the central region of the Dniester River basin [13]
Diabases predominate in Camenka Formation and inaxial zone of the banded body exceed the thickness of 30ndash40m In macroscopic point of view diabases are compactvolcanogenic rocks of a dark gray gray-brown or darkgreenish color with a relatively high specific weight Theirstructure is cryptocrystalline or crystalline in very smallgrains Between diabases discovered in the Dniester areathere are two varietiesmdashaphyric diabase and diabase withan apparently porphyric texture Usually porphyric inclu-sions have various sizes (1ndash15 millimeters) and consist ofcalcite and rarely chlorite Most diabases have an ophyticstructure and massive texture and in their composition areincluded basic plagioclase (40ndash50) monoclinic pyroxene(5ndash19) chlorite (30ndash35) epidote (3ndash7) and titanomag-netite (5ndash10)Theminerals which contained RE elements inCamenka Formation were not detected
43 Terrigenous Layers from the Vendian Lower LevelAccording to the stratigraphic schemeused byMoldavian andUkrainian geologists [20] the formations of Vendian age aredifferentiated in series which include several beds In normalsequence Moldavian Vendian is composed of OlchedayevBeds (Vol) LomozovBeds (Vlm) Cosauti Beds (Vks) LyadovaBeds (Vld) Bernashevka Beds (Vbrn) Bronnitsa Beds (Vbr)Zincov Beds (Vzn) Dzhurzhevka Beds (Vdz) Kalyus Beds
(Vkl) Pilipy Beds (Vpl) and Shebutintsy Beds (Vsb) Allthese local stratigraphic units are composed of terrigenousvarieties sandstones aleurolites mudstones tuffaceous claystone and greenstones (Table 2)
The majority of layers almost completely can be studiedeither in outcrops in northern part of the republic either inmapping drilling cores dug in areas covered by PaleozoicMesozoic and Cainozoic formations
In the region between Dniester and Prut Rivers Vendianlayers are laid-down directly in deposit on the surface ofcrystalline basement and the central region of Dniester Riverbasinmdashpartially on the Camenka diabases and Volyn Seriesmicroconglomerates
The lower limit of Vendian Formation in the Dniesterriver region has a dipping oriented to southwest (210ndash220∘)and dipping angle varies around the 401015840 (Figure 3) It shouldbe mentioned that the basement relief can be observed ingeomorphologic elements that are in direct connection withthe principal faults in the Dniester region The upper limitof Vendian Formation in the Podolian Tectonic Zone with asmall dipping to southndashsouth-western is disposed practicallyhorizontally and in the south-western of mentioned territoryin this chapter the lower limit is the same direction southndashsouth-western dipping with an angle about 201015840ndash301015840 By thissmall difference between the dipping angles of geological
Advances in Geology 9
Table2Ve
ndianageb
edsinthec
entralregion
oftheD
niesterR
iver
basin
Serie
sFo
rmations
Theb
eds(localstratigraph
icindices)
microfossilsv
arieties
(thickn
essinmeters)
Thea
verage
concentrations
ofΣRE
(La+
Ce+
Y)lowast
gt
dataarefrom
[7]
Kanilovka
Danilo
vka
Vdn
ShebutintsyB
eds(V
sb)mud
stonesa
ndbrow
nandredd
ish-brownaleurolites
with
sand
stone
intercalationsK
aniloviainsolatia
AJistVend
otaeniaantiq
uaGn
il(17ndash43
m)
54
Pilip
yBe
ds(V
pl)mud
stonesa
ndgreenish
gray
aleurolites
with
sand
stone
intercalations
Vend
otaeniaantiq
uaGn
il(18ndash38
m)
45
Mogilev-Po
dolsk
y
Nagoryany
Vng
Kalyu
sBeds(V
kl)dark
gray
with
brow
nnu
ance
mud
stonesph
osph
oriticc
oncretionscarbo
nate
inclu
sions
with
cone-in
-con
etextureV
endotaeniaantiq
uaGn
ilFu
sosqua
mulaAss
Pilitela
Ass
(55ndash80
m)
58
Dzhurzhevka
Beds
(Vdz)sand
stone
rhythm
icstratifi
catio
nsaleurolitesa
ndmud
stones
Nemiana
simplex
PalVend
otaeniaantiq
uaGn
il(10ndash
25m)
53
Jaryshev
Vjr
Zincov
Beds
(Vzn)mud
stonesrhythmicstratifi
catio
nswith
aleurolitessandstone
intercalations
(15ndash20
m)
60
Bron
nitsaB
eds(V
br)mud
stonesa
ndtuffaceou
sclaystonesgreenstonesw
ithmottledmud
stone
intercalationsB
ronicella
podolicaZa
ica-N
ov(20ndash25m
)64
Bernashe
vkaB
eds(V
brn)sandstonesw
ithmud
stone
intercalationsT
irasia
nadiscifarm
isPa
lEo
holin
iamasquensis
Gnill(5ndash20
m)
67
Mogilev
Vmg
Lyad
ovaB
eds(V
ld)mud
stonesa
ndgreensand
yaleurolitesgreensto
nesredd
ishtuffaceou
scla
ystonesin
theu
pper
levelsmdash
sand
stone
intercalationsLjadova
perjo
rata
Ass(20ndash
25m)
38
Cosau
tiBe
ds(V
ks)sand
stonesw
ithrare
gritstone
intercalations
andaleurolitesN
emiana
simplex
Pal(10ndash
18m)
65
Lomozov
Beds
(Vlm)mud
stonesw
ithaleurolites
andsand
stone
intercalations(0ndash
8m)
94Olcheda
yevB
eds(V
ol)theu
pper
levelsmdash
sand
stone
with
aleurolites
intercalationsthe
lower
levelsmdash
gritstone
with
desand
stone
insm
allsgrains
andmud
stone
intercalations(10ndash35m
)72
Volyn
Camenka
R()
Greenish
gray
aphyric
Diaba
sesw
itham
ygdaleform
impregnatio
nsof
plagiocla
se(1ndash
35m)
Soroca
Bedscon
glom
eratesm
icrocong
lomeratesarkoses
andstones(0ndash
10m)
AR-PR
1Cr
ystalline
basementrocksgneiss
escrystallin
eschistsplagiogranitesplagiomigmatites
enderbitesleucogranitesalaskites
lowast
Incompleted
atao
fspectrographica
nalysisthe
northern
partof
marketterritoryin
theF
igure1
10 Advances in Geology
limits is explained the slow increase of the thickness ofVendian Formation that in immediate nearness of Predo-brogean Depression exceeds 750ndash800 meters In contrastwith lower limit the surface of upper limit of Vendian wassubjected to relatively poor processes of denudation whichchanged the morphostructural aspect appeared after the endof sedimentogenesis processes
As a result of geochemical investigations it was estab-lished that in the lower layers of Vendian Formation theconcentration of RE elements compared with layers of upperlevels is relatively higher (Table 2) In particular it refers toOlchedayev Lomozov and Cosauti Beds of Mogilev Forma-tion For example in the southern part of the territory inOlchedayev Beds was detected an anomalous zone with quitehigh concentrations 119862La = 01 and 119862Ce = 008 [10] whichexceed the geochemical background that is approximately thesame as for Lanthanum and for Cerium
In terms of perspective of detecting some significantconcentrations of RE elements as a result of formationof mechanical aureoles consisting of zircon and mon-azite Olchedayev Lomozov and Cosauti beds represent anobject for much more detailed geological and geochemicalresearches
Olchedayev beds are composed by detrital sedimentaryrocks in big grains (varieties of conglomerates microcon-glomerates and sandstones) and mudstones or sandy mud-stones present in the layerrsquos body in form of relatively shallowintercalations
Geological section of Olchedayev beds is not stablethroughout the whole distribution area but in terms oflithological varieties which form layers and the complexstratifications of this local stratigraphic unit it is observed arelatively constant accordance in the lower levels are presentmicroconglomerates and in the upper onesmdashgritstone inbig grains Specific for Olchedayev layers is the presenceof a layer of clays and sandy clays which separate themicroconglomerates from gritstone
Geological section of Olchedayev beds constructed onbasis of mapping drillings in the southern part of the markedterritory in Figure 1 is presented in the following way
Directly on the altered surface of diabases of CamenkaFormation or on crystalline basement surface crust practi-cally devoid of erosion crust are laid-down
(1) Microconglomerates of brown color with angulargrains of quartz potash feldspar and diabases (up to20ndash25) the color is imposed by clayish cement richin iron hydroxides the thickness of this basal layervaries around 4 meters
(2) Rhythmic intercalations of arkose microconglomer-ates with sandstones in various grain of gray or gray-green color in both lithological varieties are presentinclusions of sandy clay stones and clay stones layerthicknessmdashabout 7 meters
(3) Dark gray microconglomerates with clastic grainsof quartz and potash feldspar microconglomeratecement is clayish and their thickness is 1 meter
(4) Greenish-brown and brown mudstones with thinintercalations of fines sandstone and sandy clay stonethickness 45 meters
(5) Gray and gray-reddish arkose gritstones with isolatedinclusions of quartz and potash feldspar (some grainsreach up to 5 millimeters in diameter) between thesandstones are found rare and thin intercalationsof dark gray mudstones thickness average about 7meters
(6) Gritstones of dark gray color with clayish cementthickness not exceeding 4 meters
(7) Quartz-feldspar gray and light gray sandstones indifferent grain including coarse grains are visiblehorizontal and oblique stratifications of differentgranular fractions sandstone thickness 50 meterson the quartz-feldspar sandstones are laid-down theLomozov Beds
The most common thickness of Olchedayev layers variesaround 25 meters
Sandstones and gritstones of Olchedayev Beds in theupper regions of geological section are of light gray colorIn lower areas depending on potash feldspar quantitiesthe color has reddish hues In microscopic sections areobserved sabulous silitic or mixed structures (sabulous-silitic) cement structure is silitic In terms of compositionthe rocks range from quartzose and arkose varieties Amountof feldspars (potash feldspar prevailed) in most cases doesnot exceed 50 by volume Both in the microconglomerates(also highlighted) and in the sandstones are frequent isolatedgrains of quartzite and rocks of crystalline basement In thelower levels of Olchedayev layers are found frequently smallscales of biotite
The degree of grains rounding from which are formedthe terrigenous rocks varieties of Olchedayev increases withtheir size coarse grains are round and smooth small grainsare ragged Often microconglomerates cement is amorphousmass clayish which together with rock grains imposedporosity quite evident
Accessory minerals in small quantities are presented bygarnet zircon and monazite A minus of geological researchcarried out in the mentioned region in this chapter consistedin that a mineralogical analysis which would determine thequantitative relations between zircon and monazite was notachieved As we have remarked the origin of mineralizationrich in RE elements in geological formations from the Dni-ester basin region is a great problem Additional informationwhich would facilitate the solving of this problem wouldpresent the thorough study of the separate grains of zirconandmonazite from the structure and composition andwouldbe extremely important in terms of geochronology It ispossible that the absolute ages of zircon and monazite shouldcoincide with the ages of these minerals found in crystallineformations of basement It did not exclude the case that theseminerals are different as assortment of isomorphic elementsin their chemical composition Such research are importantfor solving of various fundamental and practical geologicalproblems which can determine the origin of zircon and
Advances in Geology 11
monazite the sedimentogenes processes and the formationof mechanical aureoles with significant concentrations ofuseful components Unfortunately because of changes thathave intervened in the last decade of the past century in theRepublic of Moldova all expensive geological research wassuspended
In the Olchedayev rocks are found rare impregnationsof galena barite fluorite and xenotime (YPO
4) Because
monazite and zircon are contained isomorphic impurities ofTh and U and xenotimemdashabout 5 UO
2mdashOlchedayev Beds
are characterized by a relatively high radioactivity whichrarely reaches up to 500 and 780 micronshour
Lomozov beds are formed preponderant frommudstonesa dark gray color with mica they are intercalations ofsandstones finely dispersed The layers thickness has notbeen exceeding 5 meters In some places Lomozov rocks aremissing At level of Lomozov Beds is identified a complexlayer composed of very fine stratifications of fine-grainedsandstone and of dark gray mudstones relatively rich inminerals containingRE Because the average concentration ofLa + Ce + Y amount compared to other Vendian stratifica-tions is the largestmdash94 gt (Table 2)
The mudstones consisted of an amorphous mass ofgray color and in microscopic sections brown color withabundant additions of small scales of hydromica disposedparallel with surfaces of sedimentation On the fund of thisbasedmass are detected small granules (silitic) of quartz withangular forms In Lomozov Beds have a specific character inthe mudstones composition are often presented inclusions ofbiotite and more rarely of muscovite as elongated scales
Cosauti Beds in lithological point of view of this localstratigraphic unit are relatively homogeneous and are com-posed almost solely of sandstone Dark mudstone interca-lations and dispersed fine sandstone are marked only inpatches Cosauti sandstones have white color with sugaraspect in a homogeneous medium or small grain
In microscopic sections sandstones are psammitic clearstructure Aleurite fraction (01 millimeters) is about 5by rock volume (rarelymdash10ndash12) Large grains of quartzare frequent (about 2 millimeters) embedded in argillite-sandy mass (a few tenths of a percent) but in granulometricpoint of view sandstone are very well sorted In the Cosautibeds were discovered sandstone consist not only of quartzgrains Quartzose varieties usually contain about 10 ofdetrital material consisting of other minerals The quartz-feldspar and arkose sandstones are predominated in whichthe feldspar grains scant of above 20 (potassium feldsparis prevailing) It is common inclusions of biotite in the formof scales about 1-2 from volume Less commonly in therock small granules of quartzite are found In small isolatedgranules can be identified pyrite and magnetite Accessoryminerals are more frequent in zircon and monazite whichgenerated geochemical anomalies with relatively high con-centrations of REE
Cement of Cosauti sandstones is relatively variedchlorite-hydromicaceous (sometimes with added of kaolin ordikkite) silica or carbonated in which predominated calciteThe thickness of Cosauti Beds varies between 10 and 18meters
Compared with Olchedayev and Lomozov Beds variedby mineralogical and granulometric composition Vendiansection above Cosauti sandstones are relatively homogeneouson all distribution area A certain practical interest wouldpresent the mudstones of Kalyus Beds rich in phosphoriticconcretions
The morphostructure of Olchedayev Lomozov andCosauti beds succession (Vol + Vlm + Vks) in the Dniesterregion are presented quite homogeneous In terms oftectonic the main structural element within the mentionedterritory in this paper are presented by a segment of PodolianFaults Zone oriented in north-western direction and calledby autochthon geologists Dniester Fault (Figure 1) Effusionmagmatism with alkaline lava flows were distinguished thebeginning of a continental riftogenesis which was manifestedin later Proterozoic As a result of geological mapping ithas been shown that the basement along the Dniester Riverhas a narrow linear structure with typical features of riftvalley in which vertical dislocations amplitudes of basementblocks varies within 20ndash60m [2 3 7 10 18] Completed bythe Camenka diabase this structure in sedimentary coverlayers does not reflect practically anything This is observedby comparison of the crystalline basement relief shown inFigure 2 with the surface of lower limit of Vendian Formation(Figure 4) the latter being much smoother The crystallinebasement relief and the surface of lower limit of VendianFormation are observed linear zones oriented in transversaldirections Dniester Fault which occurred in result of thetectonic process much earliermdashin the south-west of pericra-tonic zone of the East European Platform late Archean wasformed a several tectonic faults oriented in preponderantlynorth-eastern direction [10] Perhaps along these faults hadoccurred more intensive erosion processes that had been ledto digging in the Archean relief negative linear forms
In the following way is explained the morphostructuralaspect of the succession beds which are at Vendian basedin the central region of the Dniester River basin Examiningthe summary thickness of Olchedayev Lomozov andCosautiBeds we see a series of relatively isometric areas whichhave comparatively larger thickness which is in correlationwith some earlier faults (Archean) in the region (Figure 4)Accordingly we conclude that the geological research indetection purpose of eventual essential accumulation of REelements should be continued in these areas with relativelylarger thickness of Vendian basal layers
5 Conclusion
(1) As a result of geological mapping in the basal layersof Moldavian Vendian at accessible depths for an eventualexploitation has been located REE mineralization At thesame time the prospect of these layers in the detection pointof view of some industrial accumulations of ores so far nothas been resolved Consequently in the opinion of manyexplorers studying of Vendian rocks needs to be continueduntil getting a univocal solution
(2) In terms of the geological formations of the centralregion of the Dniester river basin the minerals presenteda practical interest in terms of the formation of significant
12 Advances in Geology
0 10 20
(km)
The lower layers of platform cover
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of lower limit of the Vendian formation (m)
Distribution area of Camenka formation
minus160 minus120
minus140
minus80
minus80
minus60
minus40
0
20
30
30
30
40
40
40
40
40
40
40
40
40
50
50
50
50
50
50
50
60
60
60
60
60
80
Olchedayev-Vol Lomozov-Vlm Cosauti-Vks
Isopachites of lower Vendian layers (Vol + Vlm + Vks ) (m)
Figure 4 The lower layers of platform cover Olchedayev (Vol) Lomozov (Vlm) and Cosauti (Vks) Beds in the central region of the DniesterRiver basin [13]
accumulation of RE elements (Sc Y La Ce and Yb) aremonazite (phosphate) and zircon (silicate) probably zirconand monazite are paragenetically associated
(3) In order to locate in the underground space geo-chemical aureoles of the elements mentioned above it isnecessary to study carefully the conditions of migration andconcentration of these elements in diverse mineralogenesprocesses in conditions of the Dniester River basinmdashin theprogressive and retrograde metamorphism ultrametamor-phism metasomatic processes and training processes of thebasal layers of platform cover
(4) Based on the geological and geochemical data accu-mulated in the geological mapping to outline geochemicalaureoles and anomalies which may serve as a direct indexof the presence in crystalline and sedimentary formations ofmechanical aureoles of monazite and (or) zircon
(5) Geological research in detection purpose of eventualessential accumulation of RE elements in central region ofthe Dniester River basin should be continued in relativelylarger thickness of Vendian basal layers the OlchedayevLomozov and Cosauti Beds oriented along the Archean-Proterozoic tectonic faults
(6)The geochemical study of RE elements has remarkableimportance in interpretation and restoration of geological
processes of the geological past Because of this it is importantto investigate concentrations of these elements in differentvarieties of rocks of different ages and origins In particular itis important to establish particular paragenetic types betweenRE elements and other associated minerals to solve thegeological genetically problems
(i) to establish correlative links between particular typesof RE elements and particular types of crystalline orsedimentary rocks
(ii) to determine the origin of rocks which contain theseelements (formed in a single magmatic process in acommon metamorphic facies and in a single sedi-mentogenesis cycle)
If the detection of a deposit of zircon and monazite con-taining rare earths brings a direct practical result geochem-ical study of any region of the earth crust is of high particularimportance in geological prospection Because it solves agreat problem regarding the determination of parageneticassociations of minerals and chemical elements to determinethe type of petrographic provinces specifies geotectonicappearance of territories and to determine the links betweenlithogenic processes and palaeogeographic conditions in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Journal of
Atmospheric SciencesInternational Journal of
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Advances in
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Geological ResearchJournal of
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Geology Advances in
2 Advances in Geology
IV
IV
I
I
C
E B
II
IIIII
III
D
1
2
3
4
5
6
7
A
minus600
minus2400
minus400minus500
minus600
minus2400
minus400
minus200
minus800
minus1000
minus1200
minus1400
minus1600
minus1800
minus2200
minus2600
minus350
minus450
minus400
Figure 1 Schematicmap of geological structure of the Republic ofMoldova [1] 1mdashisohypses of Precambrian crystalline basement constructedon basis of drillings 2mdashisohypses of Precambrian crystalline basement constructed on basis of geophysical prospecting 3mdashisohypses ofHercynian crystalline basement constructed on basis of drillings 4mdashzone of maximal gravitational gradients 5mdashtectonic disjunctions6mdashPrecambrian crystalline rocks 7mdashMetamorphosed rocks of early Paleozoic age I-I Dniester Fault II-II Ciadar-Lunga Fault III-IIICahul-Ismail Fault IV-IV Ciuhur Fault AmdashUkrainian Crystalline Shield region Bmdashslope of Southwestern East European Platform CmdashThe Predobrogean Depression Dmdashnorth-west region of the Dobrogea Orogen EmdashSouth West region of the Precarpathian Depression
ex-Geological Department of MSSR (now Agency of Geo-logical Mineral Resources ofMoldovamdashAGRM) A ZaharovV Sergheev V Ciobotaru E Hiora G Fedorenko and soforth Because of changes that followed the proclamation ofthe Independence of the Republic of Moldova the researcheswhich had to be executed in a more detailed way were notrun to a successful end To some extent the geological dataand the issues addressed in this chapter are unique becausewe are not sure that in the near future in Dniester region suchworks will be undertaken
Study of the composition and origin of geological forma-tions of Archean-Proterozoic basement allowed following theevolution of substance from the earth crust beginning fromthe moment of accumulation until hypergen modificationstages of rocks in conditions of the platform
Both in the process of geological study in the field andin the process of elaborating this chapter all correspondingmaterials edited or available in AGRM funds have beenexamined with great attention
Some rather general concepts about the geological struc-ture of crystalline formations covered by much youngercomplex sedimentary layers were elaborated based on datafrom drillings executed in different years with the pur-pose of geological mapping geological and hydrogeologicalprospections On the territory between the rivers Dniesterand Prut during about four decades were executed a largenumber of drillings majority of which also crossed the base-ment rocks in the northern part of country As a rule drillingswere undertaken only for research purposes of sedimentaryrocks and because of this the opening depths of Archean andProterozoic rocks of crystalline formations ranged betweenabout 20 and 50meters Having at disposition a great numberof cores it was possible to research only composition ofcrystalline rocks from the surface of Precambrian basementThere had been several attempts on the basis of the drillingand geophysical prospecting to elaborate the geological mapsof some portions of the crystalline basement surface [2 3]and the layers of sedimentary rocks of the lower levels of
Advances in Geology 3
platform cover [4] but all such geological deductions haveproved to be arbitrary often subjective and presented more apersonal vision of researchers on the geology of earth crustin this area [5] Also rather approximately had been executedthe geological prospectings in order to solve the perspectiveof detection in the mentioned region of some significantaccumulation of rare earth elements [6]
The proposed study is one of a synthesis of geologicalresults performed by a group of researchers who have workedtogether beginning with the design field research andlaboratory analyses and ending with the generalization ofobtained data In this regard the author presents not onlythe geological vision of this group but also his own conceptconcerning the specificity of rare earths in the region ofMoldovan segment of Dniester basin
2 General Suggestions Concerningthe Geological Structure of the Territory ofthe Republic of Moldova
On the territory of the Republic ofMoldova are distinguishedseveral fragments of some regional structures which in termsof tectonic and geological evolution are different from eachother in a highlighted manner [8]
About two thirds of the territory of the republic falls in asegment of southwest pericratonic zone of the East EuropeanPlatform called by Moldavian and Ukrainian geologists theldquoMoldavian Platerdquo (Figure 1)
A part of south-eastern region is occupied by a fragmentof the Dobrogea Orogen which endorses the typical featuresof a young platform Constituted in late Paleozoic it is con-sidered an epi-Hercynian platform Crystalline basement isconstituted by metamorphosed rocks in lower metamorphicfaces and igneous intrusions and sedimentary cover about500 meters thick is formed by Mesozoic-Cainozoic age strataplaced almost parallel
Another regional structuremdashPredobrogean Depressionwhich extends to the northwest in Romaniamdashis seen bysome researchers [9] as a component part of the EastEuropean Platform At the same time the geological evolutionof this structure and tectonic processes which manifestedthemselves in the Paleozoic and especially in the earlyMesozoic allow considering the Predobrogean Depression anindependent structure with specific geological and structuralfeatures
In the northern and north-eastern regions of the Republicof Moldova (marked area in Figure 1) we can highlightthree geological-structural units crystalline basement sed-imentary cover composed of diverse rocks and Pliocene-Pleistocene formations These three geological-structuralunits in terms of age origin and composition are differentfrom each to other in a cardinal way Due to shallow depthsup to crystalline rocks of the basement and mineralizationwhich contain elements of rare earths discovered in the basallayers of sedimentary cover the central region of the DniesterRiver basin has always made up a remarkable object of studyfor geological research
3 The Petrographic Specificity ofthe Crystalline Basement Rocks
The principle of differentiation of crystalline rocks inmost cases Archean or of early Proterozoic age situatedin the basement composition was and remains a subjectof permanent discussion In geochronological-stratigraphicterms the most appropriate methodological principle in thegeological study of the south-western slope of the EastEuropean Platform is the correlation of ultrametamorphosedcrystalline formations within a regional or local geotectonicunit Basement rocks in the area reflect all the specificfeatures of geological processes that led to the formation ofthe south-western slope of the Ukrainian Crystalline Shieldwhich is situated to the north of the Dniester Faultmdashthemost important geotectonic element from the mentionedregion (Figure 1) Crystalline basement is an agglomeratecomposed of metamorphic ultrametamorphic magmaticand metasomatic rocks of different agesmdashearly Archeanand early Proterozoic In general crystalline formations arepresented in an extremely complicated way but at the sametime there are some distinguishing features that differentiatethis portion of the earth crust from other neighbouring areasAnalyzing the magmatic and ultrametamorphic processeswhich occurred in the Precambrian of Ukrainian CrystallineShield Archean and Proterozoic rocks and can be system-atized in specific formations that differ from each otherby petrographic varieties and physicochemical conditions oftheir formation [10] gneisses and crystalline schists (earlyArchean age) enderbites plagiomigmatites plagiogranites(formed as a result of anatexis processes at the geochrono-logical limit of later Archeanndashearly Proterozoic) alaskitesleucogranites (early Proterozoic age of palingenesis origin)mdashTable 1 Having a predominantly granitic composition thesevarieties of rocks differ from each other only in the auxiliaryindex (accessory mineralizations presence of geochemicalaureoles and geophysical anomalies) It should bementionedthat in the composition of these rocks with rare exceptionspredominate plagioclases (oligoclase-andesine) and almost inall lithological varieties often in significant quantities is alsopresented hypersthene
Is typical associations of accessory minerals consti-tuted from zircon monazite garnet apatite magnetiteand ilmenite which with some exceptions are presentalmost in all petrology varieties It is significant that in theoldest rocks of the gneisses formation (dominate biotite-amphibole-hypersthene plagiogneisses) of early Archean agemonazitemdashone of the most important minerals in geologicalformations of the basement from area that contains rareearthsmdashwas found only occasionally and zircon is found inform of small isolated grains in relatively small quantitiesin almost all varieties of gneisses and crystalline schistsAs an accessory mineral monazite frequently occurs inmineralogical composition of the ultrametamorphic varietiesof enderbite and alaskite formations
We would like to pay attention to the fact the major-ity of zircon grains which are in ultrametamorphic rockscomposition have round forms with melting traces of the
4 Advances in Geology
Table1Precam
briancrystalline
form
ations
inthes
outh-w
estregionof
theU
krainian
Crystalline
Shieldandaccessorym
ineralconcentrations
which
containelem
entsof
REgrou
p(C
entral
region
oftheD
niesterR
iver
basin
)
Num
ber
Form
ations
andcomplexes
ofrockslowast
Agelowast
106years
Petro
graphicv
arietie
sMineralogicalcompo
sition
Accessoriesm
inerals
1Ch
arno
ckitesa
ndgranites
form
ation
Lowe
rProterozoic
(200
0ndash2200)
Alaskite
Quartz(20ndash4
0)
Microcline
(35ndash70)
Plagioclasemdash
Pl20ndash25(5ndash35
)Biotite
(0ndash5)
Zircon
(5ndash2
00gt)
Mon
azite
(30ndash
250g
t)Magnetite(9ndash
4009
gt)
Apatite
(sim14gt)
Garnet(7ndash17gt)
2Leucogranite
Quartz(20ndash35
)Microcline
(5ndash35
)Plagioclasemdash
Pl20ndash25(30ndash
35)
Magnetite(sim20
gt)
Zircon
(656
gt)
Mon
azite
(1270g
t)Ap
atite
(sim20
gt)
3Plagiogranitesa
ndtonalities
form
ation
Upp
erArcheanndashL
ower
Proterozoic
(2550ndash
2800)
Plagiomigmatite
Quartz(20ndash30
)Plagioclasemdash
Pl25ndash30(60ndash
80)
Biotite
(lt10)
Microcline
(lt5
)
Apatitesim
Mon
azite
(12ndash
211g
t)Zircon
(12ndash
190g
t)Garnet(23ndash183
gt)
4Plagiogranite
Quartz(20ndash50
)Plagioclasemdash
Pl25ndash30(35ndash70)
Pyroxene
(5ndash15
)Biotitesim
Microclinesim
Apatite
(10ndash
40gt)
Zircon
(sim10
gt)
Mon
azitesim
Magnetite(200g
t)Ilm
enite
(1430
gt)
5En
derbitesformation
Upp
erArchean
(2850ndash
3150)
Enderbite
Quartz(20ndash30
)Plagioclasemdash
Pl25(50ndash
80)
Pyroxene
mon
oclin
ic(5ndash15
)Hypersth
ene(5ndash20)
Biotite
(lt5
)Microclinesim
Apatite
(228ndash1080g
t)Zircon
(20ndash
30gt)
Mon
azitesim
Ilmenite
(sim658g
t)Magnetite
(3317ndash7550
gt)
6Th
ecom
plex
ofmetam
orph
icrocks
Lower
Archean
(3300ndash
3750)
Biotite-pyroxeneP
lagiogneiss
Quartz(10ndash30
)Plagioclasemdash
Pl30(40ndash
60)
Pyroxene
mon
oclin
ic(5-4)
Hypersth
ene(lt10)
Biotite
(10ndash
15)
Microcline
(lt10)
Apatite
(17ndash680g
t)Zircon
(8ndash6
0)gt
Ilmenite
(sim1000
gt)
Magnetite
(24ndash
1348
gt)
7Biotite-amph
ibole-pyroxene-
plagiocla
sewith
magnetite
crystalline
schist
Plagioclasemdash
Pl30(10ndash
70)
Pyroxene
mon
oclin
ic(sim15)
Hornb
lend
e(sim25)
Biotite
(sim20)
Quartz(lt5
)
Magnetite(5ndash10gt)
Apatite
(sim170g
t)Zircon
(sim20
0gt)
lowast
Accordingto
thes
tratigraph
icschemee
labo
ratedby
theR
egionalStratigraph
icCom
mittee
from
Ukraine1984
Advances in Geology 5
external zones Perhaps because of higher refractory prop-erties this accessory mineral passed from older geologicalformations in the younger ones without essential changesthat are imposed by anatexis and palingenetic processesProbably it also refers to monazite present in the samevarieties of rocks It produces the impression that multipleacts of progressive metamorphism ultrametamorphism andretrograde metamorphism that took place during an enor-mous period of geological time and modified in a cardinalway all petrologic varieties of the platform basement anddid not influence the redistribution in underground spaceof zircon and monazite The above-presented affirmationis supported by geochronological research data achievedthrough the radiological methods by Ukrainian geologists Inthe regions of Ukrainian Crystalline Shield slopemdashadjacentarea of Dniester River basin monazite and zircon in rockcomposition from formations mentioned above practicallyhave one and the same Archean age [11]
Many authors link the formation of concentrations ofRE elements in the Dniester region with the presence ofaccessory monazite and zircon which are present in compo-sition of different petrologic and lithological varieties of lateArchean early Proterozoic and Vendian ages [5] Remarkingthe high correlation coefficient between zircon and monazite(120588 = 073) and satisfactory degree of correlation (120578 =86 gt 3) we can assume that these two minerals interms of geology are syngenetic and probably as accessoryminerals were formed at the same time in one and the samepetrological formation At the same time we would liketo emphasize that monazite in the complex composition ofmetamorphic rocks of early Archaic age practically was notfound On the basis of the data from previous mineralogicaland geochemical researches it was determined that monaziteweight in geochemical aureoles formation (RE-elements) ismuch higher than that of zircon [12] We would like to notethat between crystalline and terrigenous formations in thisarea in quite small quantities can also be found othermineralscontaining rare earths (xenotime and allanite) [10]
Most of rare earth minerals including zircon and mon-azite are constituents of granite and nepheline-syenite peg-matites There are known endogenous deposits of the rareearths which are in geological-genetic relations with alkalinegranites intrusive alkaline ultrabasic rocks syenites (rich inpyrochlore) and pneumatolytic hydrothermal formations Ifwe examine the mineralogical compositions of the meta-morphic and ultrametamorphic rocks varieties in the centralregion of the Dniester River basin we will observe that inthese types of crystalline rocks in no way can form parage-netic associations with minerals which contain rare earths[9] It is possible that accessory mineralization of zircon andmonazite has no directly bearing to the origin of formationsfrom this area but can be part of some blocks of the earthrsquoscrust from neighboring regions For example in differentregions of the Ukrainian Crystalline Shield (Jitomir Vinita)in alkaline granitic and pegmatite rocks with monazite andzircon were found significant concentrations of RE elements(Lanthanum Cerium and Neodymium) [13]
From the above-said results that the issue of mineralsrsquoorigin (especially of zircon andmonazite) which contain rare
earths found in different varieties of crystalline rocks in thesouth-western East European Platform remains open
In terms of fundamental geotectonic concepts the oldestparts of the continental earth crustmdashcrystalline shieldsmdashduring the geologic time underwent several cardinal tectonicmodifications [14] Therefore it is presumed that in thetectonic cycle of theWhite Sea (Archean) the manifestationswhich are well observed in the Baltic Crystalline Shieldformations ended with intensive folding metamorphosingand profound granitization phenomena For correspondinggeological epoch is characteristic the formation of somegranite-gneiss domes delimited in the initial phase by linearzones consisting of volcanogenic-sedimentary rocks Atpresent these linear areas are transformed into relatively nar-row synclinorium formed of profoundly modified rocks indifferent metamorphic facies As a result of the epi-Archeantectonic processes (until early Proterozoic) we can assumethat in such synclinorium took place several epeirogenicmovements of crystalline basement concomitantly accom-panied by various destructive processes Consequently incertain places emerged aulacogens delimited by lineamentswithin which are found many remains of Archean blocksand areas with well-pronounced progressive and retrogrademetamorphism manifestations A similar structure could bethe Dniester Fault which de facto represents a segmentof Podolian Tectonic Faults Zone [15] and which delimitsin the south-western part another crystalline shield of EastEuropean PlatformmdashUkrainian Crystalline Shield Tectonicphenomena of early Proterozoic period ended with theconsolidation of the crystalline basement from region Insubsequent geological periods the tectonic activity graduallyreduced tominimum introducing in theDniester-Prut inter-fluves region only some structural changes genetically linkedto the evolution of Dniester Fault For example in Ripheanaround 950 million years along the Podolian Tectonic FaultsZone in a relatively weak process of continental riftogenesisoccurred alkaline lava flows in the result of which lenticularbodies of diabases were formed
Manifestations of effusive or intrusive magmatism inArchean-early Proterozoic in the central region of the Dni-ester River basin have not been determined It is possible thatultrametamorphic processes that took place in this regionin late Archean-early Proterozoic probably ldquoretouchedrdquo com-pletely initial igneous rocks in the area Consequently we cansay that zircon and monazite in the initial stages of geologic-structural formation of pericratonic region of south-westernpart of East European Platformwere already formed and werepart of the composition of pre-rocks
As mentioned above most endogenous deposits of REare genetically related either with alkaline granites intrusionsor alkaline typical intrusions Examining the contribution ofmagmatism in the evolution of earth crust it is determinedthat the alkaline magmatism events began about 25ndash27billion years ago and in an intensive way developed inPhanerozoic and arrived to maximal action in the MesozoicIn general alkaline rocks older than 27 billion years in theearth crust formations have not been found [16]Thus it maybe deduced that the origin of zircon and monazite detectedin geological formations in Dniester region in no way can be
6 Advances in Geology
linked with alkaline intrusions which may have been formedin the Ukrainian Crystalline Shield
It is obvious that theseminerals were formed however in amagmatic process unexplained so far by geologists interestedin the rare earths in the area and the issue of RE origin incomposition of metamorphic and ultrametamorphic rocksof the crystalline basement in the south-western part ofEast European Platform requires a serious investigation to besolved
There exist industrial concentrations of REminerals bothof endogenous type and metamorfogenic one Rare earthdeposits related tometamorphic formations are characterizedby relatively homogeneous distribution of RE elements onareas of significant extension and are presented in generallyby migmatites gneiss and metamorphosed conglomerateswith monazite of other origin It is not excluded that inthe geological formations of the crystalline basement arepresent accumulations of monazite (and zircon) located inplagiomigmatites and leucogranites which have a rather largedistribution in the Dniester region
4 Sedimentary Formations andDetection Premises of Concentrations ofRare Earths Elements
41 The Types of Hypergen Deposits of Rare Earths ElementsRare earths minerals of exogenous origin until now are notknown At the same time most rare earth deposits exploitedat present are of exogenous type
According to systematization of useful mineral depositstypes [17] hypergen deposits of RE are grouped into threetypes
(1) residual which are formed as a result of alterationof granite syenite nepheline-syenite rocks rich inmonazite sphene pyrochlore thorianite cerianiteand formation in erosion crust of a zone rich with REof cerium subgroup Nb Zr Th and Y
(2) sedimentary-detrital (a) alluvial lands formed fromconcentrations of stable minerals in hypergen zonesuch as monazite ilmenorutile zircon uranothorite(b) eluvium-adobe lands with high concentrationsof xenotime pyrochlore fergusonite thorite and (c)mineral lands of coastal areas consisting of significantaccumulations of monazite ilmenite rutile and zir-con
(3) sedimentary and sedimentary-biogenic (a) phospho-rites (b) sands rich in REminerals (c) shales and (d)fossil reminiscences
Referring to the territory in northern and north-eastern partof Republic of Moldova in the basal layers of sedimentarycover may be present the RE deposits such as detritalsediments This confirms the results of recent geological-geochemical researches carried out in the last decades of thelast century [7 18]
In hypergen areamonazite is a quite stable mineral Beingresistant to the action of exogenous agents it is not broken
down and in the following way in rubbly grains is keptvery long periods of geological timeTherefore the monazitepresent in crystalline rocks of Archean and early Proterozoicage is also found in sedimentary rocks of platform cover in thecentral region of the Dniester River basin Since the specificweight of monazite is quite high (exceeding 50 gcm3) inthe erosion process of rocks with accessory monazite andfurther sedimentogenesis of disintegrated material often areformed mechanical aureoles of this mineral Therefore it isexplained that the monazite in detrital sedimentary layersmay be present in concentrations much higher than itsconcentrations in the syngenetic rocks
For example in a drilling for geological mapping dugin the south of the marked territory in Figure 1 has beendetected a geochemical anomaly with maximum concentra-tions of lanthanum (01) and cerium (008) generated bymonazite the concentration of which in basal layers of thesedimentary cover varies between 05 and 218 gt [10]
In a similar process are also formed the mechanicalaureoles of zircon
Sedimentary cover in central region of the DniesterRiver basin is made up of several complex beds placedalmost horizontally In terms of geochronology of lithologicalcomposition of sedimentation conditions and diageneticprocesses in slope cover of southwestern part of theEast Euro-pean Platform are identified four formations and sedimentaryrock complexes Vendian Formation Ordovician-Silurianstratigraphic Complex Cretaceous Formation and NeogeneFormation (note currently in many countries the name ofstratigraphic unit Vendian is replaced with Ediacaran butin Republic of Moldova so far remain the same names ofstratigraphic units used in Russia)
Ordovician-Silurian beds consisting prevailingly oflimestone-dolomite varieties limestone-siliceous rocks ofCretaceous and diversity of limestone sand and clay varietiesof Neogene age in terms of the problem approached in thischapter unlike the Vendian basal layers of sedimentarycover do not present any practical interest
By direct comparison it was demonstrated that thegeological section of Podolian Vendian is stratotype almostfor all formations of this age opened in different regionsof the East European Platform Thus Vendian age layerssituated in natural cropping or crossed by drilling in the northand north-eastern zone of Republic of Moldova presenta southeastern fragment of Podolian Vendian and in anatural way without assumptions the stratigraphic scheme ofUkrainian geologists can also be applied in the Dniester riverbasin conditions For a rather complete documentation aboutVendian Formation in the region we make reference to aquite ample synthesis work prepared by Ukrainian geologistsforTheThird International Symposium on Cambrian System(Kiev 1990) [19]
42 Camenka Formation Directly on the surface of crys-talline basement are laid-down in the deposit the layersof Camenka Formation constituted of basal conglomeratesand diabases probably of Riphean age The formation body(average thickness about 20 meters) has a lenticular-flat
Advances in Geology 7
The distribution area of Camenka formation
Central region of the Dniester River basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of crystalline basement surface (m)Isopachites of Camenka formation (m)
0 10 20
(km) minus280
minus240
minus160
20
40minus140minus260
minus200
minus180
minus160
minus80
minus80
60
minus60
minus200
minus100minus140 1
0
10
10
10
10
10
20
20
20
20
20
20
20
20
20
20
minus40
minus20
minus20
0
30
0
0
30
30
80
Figure 2 The distribution area of Camenka Formation in the central region of the Dniester River basin [13]
aspect is relatively narrow (8ndash10 kilometers in cross section)is oriented in a north-western direction and covers thelinear-depressive zone of Dniester Fault (Figure 2) We canassume that the centers of lenticular forms coincide withchannels throughwhich on the earth surface poured lavawithalkaline composition specific for early stages of continentalriftogenesisThe phenomenon took place in later Proterozoicin one of the last phases of tectonic activity in south-westernareas of the East European Platform
Camenka Formation consists of diabases and a basal layerof microconglomerates and conglomerates (Soroca Beds)
Lithological varieties of Soroca in the spread region ofFormation Camenka do not present an integral structuralunit Firstly these lithological varieties are in deposits just inthe spread zone of diabases and only in someplaces vulcanitesof Camenka Formation are laid-down directly in depositon the surface of crystalline basement Perhaps Sorocabasal beds in the mentioned region had had a much largespread but because of denudation processes were preservedonly under diabases Thickness of Soroca Beds crossed bydrilling mapping varies from 05 to 35 meters Rocks aredistinguished by their mineralogical composition and areformed from an unselected rubbly material conglomeratesconglomerate-breccias microconglomerates (predominant)coarse-grained sandstones and arkose sandstones (rarely)
The rubbly material is presented by slightly rounded grainsof crystalline basement rocksmdashquartzite potash feldsparand biotite scales cemented with a brown argilitic materialCement volume typically exceeds 50 by volume In thefollowing way most of Soroca Bedsrsquo rocks differ by theirspecific brown color
Arkose sandstones and microconglomerates that can befound in the composition of the basal layers of Camenka For-mation are massive rocks hard of gray-green or pink-graycolor have sabulous structures and consist of plagioclase (upto 50ndash60) potash feldspar (up to 15) quartz (25 to 35)cement and grains of basement rocks
In clastic material are prevalent semirounded or ruggedforms and grainsrsquo sizes range from 10ndash15 millimeters(microconglomerates) 10ndash01 millimeters (sandstones)01 millimeters (sandy mudstones) Cement has a highporosity and has a kaolin-hydromicaceous kaolin-chlorite-hydromicaceous or kaolin composition
From accessory minerals are present small grains ofgarnet zircon monazite apatite and titanomagnetite
The rocks of Soroca Beds have a specific radioactivity rel-atively high (30ndash35 micronshour) imposed by the presenceof isomorphic thorium in the monazite composition
Based on geochemical investigations of Sorocamicrocon-glomerate were found relatively high concentrations of La
8 Advances in Geology
0 10 20
(km)
The morfostructure of Vendian formation
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isopachites of Vendian layers (m)Isohypses of upper limit of the Vendian formation (m)
minus80
minus60
minus40
minus20
minus20
0
0
0
20
20
20
20
40
40
40
40
60
60
60
60
80
80
80
80
100
100
100
120
120
120
140
140
140
160
160
160
180
180
180
180
180
200
200
200
200
200
200
220
220
220
220
220
240
240
240
240
240
260
260
260
280
280
280300
Figure 3 The morphostructure of Vendian Formation in the central region of the Dniester River basin [13]
Diabases predominate in Camenka Formation and inaxial zone of the banded body exceed the thickness of 30ndash40m In macroscopic point of view diabases are compactvolcanogenic rocks of a dark gray gray-brown or darkgreenish color with a relatively high specific weight Theirstructure is cryptocrystalline or crystalline in very smallgrains Between diabases discovered in the Dniester areathere are two varietiesmdashaphyric diabase and diabase withan apparently porphyric texture Usually porphyric inclu-sions have various sizes (1ndash15 millimeters) and consist ofcalcite and rarely chlorite Most diabases have an ophyticstructure and massive texture and in their composition areincluded basic plagioclase (40ndash50) monoclinic pyroxene(5ndash19) chlorite (30ndash35) epidote (3ndash7) and titanomag-netite (5ndash10)Theminerals which contained RE elements inCamenka Formation were not detected
43 Terrigenous Layers from the Vendian Lower LevelAccording to the stratigraphic schemeused byMoldavian andUkrainian geologists [20] the formations of Vendian age aredifferentiated in series which include several beds In normalsequence Moldavian Vendian is composed of OlchedayevBeds (Vol) LomozovBeds (Vlm) Cosauti Beds (Vks) LyadovaBeds (Vld) Bernashevka Beds (Vbrn) Bronnitsa Beds (Vbr)Zincov Beds (Vzn) Dzhurzhevka Beds (Vdz) Kalyus Beds
(Vkl) Pilipy Beds (Vpl) and Shebutintsy Beds (Vsb) Allthese local stratigraphic units are composed of terrigenousvarieties sandstones aleurolites mudstones tuffaceous claystone and greenstones (Table 2)
The majority of layers almost completely can be studiedeither in outcrops in northern part of the republic either inmapping drilling cores dug in areas covered by PaleozoicMesozoic and Cainozoic formations
In the region between Dniester and Prut Rivers Vendianlayers are laid-down directly in deposit on the surface ofcrystalline basement and the central region of Dniester Riverbasinmdashpartially on the Camenka diabases and Volyn Seriesmicroconglomerates
The lower limit of Vendian Formation in the Dniesterriver region has a dipping oriented to southwest (210ndash220∘)and dipping angle varies around the 401015840 (Figure 3) It shouldbe mentioned that the basement relief can be observed ingeomorphologic elements that are in direct connection withthe principal faults in the Dniester region The upper limitof Vendian Formation in the Podolian Tectonic Zone with asmall dipping to southndashsouth-western is disposed practicallyhorizontally and in the south-western of mentioned territoryin this chapter the lower limit is the same direction southndashsouth-western dipping with an angle about 201015840ndash301015840 By thissmall difference between the dipping angles of geological
Advances in Geology 9
Table2Ve
ndianageb
edsinthec
entralregion
oftheD
niesterR
iver
basin
Serie
sFo
rmations
Theb
eds(localstratigraph
icindices)
microfossilsv
arieties
(thickn
essinmeters)
Thea
verage
concentrations
ofΣRE
(La+
Ce+
Y)lowast
gt
dataarefrom
[7]
Kanilovka
Danilo
vka
Vdn
ShebutintsyB
eds(V
sb)mud
stonesa
ndbrow
nandredd
ish-brownaleurolites
with
sand
stone
intercalationsK
aniloviainsolatia
AJistVend
otaeniaantiq
uaGn
il(17ndash43
m)
54
Pilip
yBe
ds(V
pl)mud
stonesa
ndgreenish
gray
aleurolites
with
sand
stone
intercalations
Vend
otaeniaantiq
uaGn
il(18ndash38
m)
45
Mogilev-Po
dolsk
y
Nagoryany
Vng
Kalyu
sBeds(V
kl)dark
gray
with
brow
nnu
ance
mud
stonesph
osph
oriticc
oncretionscarbo
nate
inclu
sions
with
cone-in
-con
etextureV
endotaeniaantiq
uaGn
ilFu
sosqua
mulaAss
Pilitela
Ass
(55ndash80
m)
58
Dzhurzhevka
Beds
(Vdz)sand
stone
rhythm
icstratifi
catio
nsaleurolitesa
ndmud
stones
Nemiana
simplex
PalVend
otaeniaantiq
uaGn
il(10ndash
25m)
53
Jaryshev
Vjr
Zincov
Beds
(Vzn)mud
stonesrhythmicstratifi
catio
nswith
aleurolitessandstone
intercalations
(15ndash20
m)
60
Bron
nitsaB
eds(V
br)mud
stonesa
ndtuffaceou
sclaystonesgreenstonesw
ithmottledmud
stone
intercalationsB
ronicella
podolicaZa
ica-N
ov(20ndash25m
)64
Bernashe
vkaB
eds(V
brn)sandstonesw
ithmud
stone
intercalationsT
irasia
nadiscifarm
isPa
lEo
holin
iamasquensis
Gnill(5ndash20
m)
67
Mogilev
Vmg
Lyad
ovaB
eds(V
ld)mud
stonesa
ndgreensand
yaleurolitesgreensto
nesredd
ishtuffaceou
scla
ystonesin
theu
pper
levelsmdash
sand
stone
intercalationsLjadova
perjo
rata
Ass(20ndash
25m)
38
Cosau
tiBe
ds(V
ks)sand
stonesw
ithrare
gritstone
intercalations
andaleurolitesN
emiana
simplex
Pal(10ndash
18m)
65
Lomozov
Beds
(Vlm)mud
stonesw
ithaleurolites
andsand
stone
intercalations(0ndash
8m)
94Olcheda
yevB
eds(V
ol)theu
pper
levelsmdash
sand
stone
with
aleurolites
intercalationsthe
lower
levelsmdash
gritstone
with
desand
stone
insm
allsgrains
andmud
stone
intercalations(10ndash35m
)72
Volyn
Camenka
R()
Greenish
gray
aphyric
Diaba
sesw
itham
ygdaleform
impregnatio
nsof
plagiocla
se(1ndash
35m)
Soroca
Bedscon
glom
eratesm
icrocong
lomeratesarkoses
andstones(0ndash
10m)
AR-PR
1Cr
ystalline
basementrocksgneiss
escrystallin
eschistsplagiogranitesplagiomigmatites
enderbitesleucogranitesalaskites
lowast
Incompleted
atao
fspectrographica
nalysisthe
northern
partof
marketterritoryin
theF
igure1
10 Advances in Geology
limits is explained the slow increase of the thickness ofVendian Formation that in immediate nearness of Predo-brogean Depression exceeds 750ndash800 meters In contrastwith lower limit the surface of upper limit of Vendian wassubjected to relatively poor processes of denudation whichchanged the morphostructural aspect appeared after the endof sedimentogenesis processes
As a result of geochemical investigations it was estab-lished that in the lower layers of Vendian Formation theconcentration of RE elements compared with layers of upperlevels is relatively higher (Table 2) In particular it refers toOlchedayev Lomozov and Cosauti Beds of Mogilev Forma-tion For example in the southern part of the territory inOlchedayev Beds was detected an anomalous zone with quitehigh concentrations 119862La = 01 and 119862Ce = 008 [10] whichexceed the geochemical background that is approximately thesame as for Lanthanum and for Cerium
In terms of perspective of detecting some significantconcentrations of RE elements as a result of formationof mechanical aureoles consisting of zircon and mon-azite Olchedayev Lomozov and Cosauti beds represent anobject for much more detailed geological and geochemicalresearches
Olchedayev beds are composed by detrital sedimentaryrocks in big grains (varieties of conglomerates microcon-glomerates and sandstones) and mudstones or sandy mud-stones present in the layerrsquos body in form of relatively shallowintercalations
Geological section of Olchedayev beds is not stablethroughout the whole distribution area but in terms oflithological varieties which form layers and the complexstratifications of this local stratigraphic unit it is observed arelatively constant accordance in the lower levels are presentmicroconglomerates and in the upper onesmdashgritstone inbig grains Specific for Olchedayev layers is the presenceof a layer of clays and sandy clays which separate themicroconglomerates from gritstone
Geological section of Olchedayev beds constructed onbasis of mapping drillings in the southern part of the markedterritory in Figure 1 is presented in the following way
Directly on the altered surface of diabases of CamenkaFormation or on crystalline basement surface crust practi-cally devoid of erosion crust are laid-down
(1) Microconglomerates of brown color with angulargrains of quartz potash feldspar and diabases (up to20ndash25) the color is imposed by clayish cement richin iron hydroxides the thickness of this basal layervaries around 4 meters
(2) Rhythmic intercalations of arkose microconglomer-ates with sandstones in various grain of gray or gray-green color in both lithological varieties are presentinclusions of sandy clay stones and clay stones layerthicknessmdashabout 7 meters
(3) Dark gray microconglomerates with clastic grainsof quartz and potash feldspar microconglomeratecement is clayish and their thickness is 1 meter
(4) Greenish-brown and brown mudstones with thinintercalations of fines sandstone and sandy clay stonethickness 45 meters
(5) Gray and gray-reddish arkose gritstones with isolatedinclusions of quartz and potash feldspar (some grainsreach up to 5 millimeters in diameter) between thesandstones are found rare and thin intercalationsof dark gray mudstones thickness average about 7meters
(6) Gritstones of dark gray color with clayish cementthickness not exceeding 4 meters
(7) Quartz-feldspar gray and light gray sandstones indifferent grain including coarse grains are visiblehorizontal and oblique stratifications of differentgranular fractions sandstone thickness 50 meterson the quartz-feldspar sandstones are laid-down theLomozov Beds
The most common thickness of Olchedayev layers variesaround 25 meters
Sandstones and gritstones of Olchedayev Beds in theupper regions of geological section are of light gray colorIn lower areas depending on potash feldspar quantitiesthe color has reddish hues In microscopic sections areobserved sabulous silitic or mixed structures (sabulous-silitic) cement structure is silitic In terms of compositionthe rocks range from quartzose and arkose varieties Amountof feldspars (potash feldspar prevailed) in most cases doesnot exceed 50 by volume Both in the microconglomerates(also highlighted) and in the sandstones are frequent isolatedgrains of quartzite and rocks of crystalline basement In thelower levels of Olchedayev layers are found frequently smallscales of biotite
The degree of grains rounding from which are formedthe terrigenous rocks varieties of Olchedayev increases withtheir size coarse grains are round and smooth small grainsare ragged Often microconglomerates cement is amorphousmass clayish which together with rock grains imposedporosity quite evident
Accessory minerals in small quantities are presented bygarnet zircon and monazite A minus of geological researchcarried out in the mentioned region in this chapter consistedin that a mineralogical analysis which would determine thequantitative relations between zircon and monazite was notachieved As we have remarked the origin of mineralizationrich in RE elements in geological formations from the Dni-ester basin region is a great problem Additional informationwhich would facilitate the solving of this problem wouldpresent the thorough study of the separate grains of zirconandmonazite from the structure and composition andwouldbe extremely important in terms of geochronology It ispossible that the absolute ages of zircon and monazite shouldcoincide with the ages of these minerals found in crystallineformations of basement It did not exclude the case that theseminerals are different as assortment of isomorphic elementsin their chemical composition Such research are importantfor solving of various fundamental and practical geologicalproblems which can determine the origin of zircon and
Advances in Geology 11
monazite the sedimentogenes processes and the formationof mechanical aureoles with significant concentrations ofuseful components Unfortunately because of changes thathave intervened in the last decade of the past century in theRepublic of Moldova all expensive geological research wassuspended
In the Olchedayev rocks are found rare impregnationsof galena barite fluorite and xenotime (YPO
4) Because
monazite and zircon are contained isomorphic impurities ofTh and U and xenotimemdashabout 5 UO
2mdashOlchedayev Beds
are characterized by a relatively high radioactivity whichrarely reaches up to 500 and 780 micronshour
Lomozov beds are formed preponderant frommudstonesa dark gray color with mica they are intercalations ofsandstones finely dispersed The layers thickness has notbeen exceeding 5 meters In some places Lomozov rocks aremissing At level of Lomozov Beds is identified a complexlayer composed of very fine stratifications of fine-grainedsandstone and of dark gray mudstones relatively rich inminerals containingRE Because the average concentration ofLa + Ce + Y amount compared to other Vendian stratifica-tions is the largestmdash94 gt (Table 2)
The mudstones consisted of an amorphous mass ofgray color and in microscopic sections brown color withabundant additions of small scales of hydromica disposedparallel with surfaces of sedimentation On the fund of thisbasedmass are detected small granules (silitic) of quartz withangular forms In Lomozov Beds have a specific character inthe mudstones composition are often presented inclusions ofbiotite and more rarely of muscovite as elongated scales
Cosauti Beds in lithological point of view of this localstratigraphic unit are relatively homogeneous and are com-posed almost solely of sandstone Dark mudstone interca-lations and dispersed fine sandstone are marked only inpatches Cosauti sandstones have white color with sugaraspect in a homogeneous medium or small grain
In microscopic sections sandstones are psammitic clearstructure Aleurite fraction (01 millimeters) is about 5by rock volume (rarelymdash10ndash12) Large grains of quartzare frequent (about 2 millimeters) embedded in argillite-sandy mass (a few tenths of a percent) but in granulometricpoint of view sandstone are very well sorted In the Cosautibeds were discovered sandstone consist not only of quartzgrains Quartzose varieties usually contain about 10 ofdetrital material consisting of other minerals The quartz-feldspar and arkose sandstones are predominated in whichthe feldspar grains scant of above 20 (potassium feldsparis prevailing) It is common inclusions of biotite in the formof scales about 1-2 from volume Less commonly in therock small granules of quartzite are found In small isolatedgranules can be identified pyrite and magnetite Accessoryminerals are more frequent in zircon and monazite whichgenerated geochemical anomalies with relatively high con-centrations of REE
Cement of Cosauti sandstones is relatively variedchlorite-hydromicaceous (sometimes with added of kaolin ordikkite) silica or carbonated in which predominated calciteThe thickness of Cosauti Beds varies between 10 and 18meters
Compared with Olchedayev and Lomozov Beds variedby mineralogical and granulometric composition Vendiansection above Cosauti sandstones are relatively homogeneouson all distribution area A certain practical interest wouldpresent the mudstones of Kalyus Beds rich in phosphoriticconcretions
The morphostructure of Olchedayev Lomozov andCosauti beds succession (Vol + Vlm + Vks) in the Dniesterregion are presented quite homogeneous In terms oftectonic the main structural element within the mentionedterritory in this paper are presented by a segment of PodolianFaults Zone oriented in north-western direction and calledby autochthon geologists Dniester Fault (Figure 1) Effusionmagmatism with alkaline lava flows were distinguished thebeginning of a continental riftogenesis which was manifestedin later Proterozoic As a result of geological mapping ithas been shown that the basement along the Dniester Riverhas a narrow linear structure with typical features of riftvalley in which vertical dislocations amplitudes of basementblocks varies within 20ndash60m [2 3 7 10 18] Completed bythe Camenka diabase this structure in sedimentary coverlayers does not reflect practically anything This is observedby comparison of the crystalline basement relief shown inFigure 2 with the surface of lower limit of Vendian Formation(Figure 4) the latter being much smoother The crystallinebasement relief and the surface of lower limit of VendianFormation are observed linear zones oriented in transversaldirections Dniester Fault which occurred in result of thetectonic process much earliermdashin the south-west of pericra-tonic zone of the East European Platform late Archean wasformed a several tectonic faults oriented in preponderantlynorth-eastern direction [10] Perhaps along these faults hadoccurred more intensive erosion processes that had been ledto digging in the Archean relief negative linear forms
In the following way is explained the morphostructuralaspect of the succession beds which are at Vendian basedin the central region of the Dniester River basin Examiningthe summary thickness of Olchedayev Lomozov andCosautiBeds we see a series of relatively isometric areas whichhave comparatively larger thickness which is in correlationwith some earlier faults (Archean) in the region (Figure 4)Accordingly we conclude that the geological research indetection purpose of eventual essential accumulation of REelements should be continued in these areas with relativelylarger thickness of Vendian basal layers
5 Conclusion
(1) As a result of geological mapping in the basal layersof Moldavian Vendian at accessible depths for an eventualexploitation has been located REE mineralization At thesame time the prospect of these layers in the detection pointof view of some industrial accumulations of ores so far nothas been resolved Consequently in the opinion of manyexplorers studying of Vendian rocks needs to be continueduntil getting a univocal solution
(2) In terms of the geological formations of the centralregion of the Dniester river basin the minerals presenteda practical interest in terms of the formation of significant
12 Advances in Geology
0 10 20
(km)
The lower layers of platform cover
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of lower limit of the Vendian formation (m)
Distribution area of Camenka formation
minus160 minus120
minus140
minus80
minus80
minus60
minus40
0
20
30
30
30
40
40
40
40
40
40
40
40
40
50
50
50
50
50
50
50
60
60
60
60
60
80
Olchedayev-Vol Lomozov-Vlm Cosauti-Vks
Isopachites of lower Vendian layers (Vol + Vlm + Vks ) (m)
Figure 4 The lower layers of platform cover Olchedayev (Vol) Lomozov (Vlm) and Cosauti (Vks) Beds in the central region of the DniesterRiver basin [13]
accumulation of RE elements (Sc Y La Ce and Yb) aremonazite (phosphate) and zircon (silicate) probably zirconand monazite are paragenetically associated
(3) In order to locate in the underground space geo-chemical aureoles of the elements mentioned above it isnecessary to study carefully the conditions of migration andconcentration of these elements in diverse mineralogenesprocesses in conditions of the Dniester River basinmdashin theprogressive and retrograde metamorphism ultrametamor-phism metasomatic processes and training processes of thebasal layers of platform cover
(4) Based on the geological and geochemical data accu-mulated in the geological mapping to outline geochemicalaureoles and anomalies which may serve as a direct indexof the presence in crystalline and sedimentary formations ofmechanical aureoles of monazite and (or) zircon
(5) Geological research in detection purpose of eventualessential accumulation of RE elements in central region ofthe Dniester River basin should be continued in relativelylarger thickness of Vendian basal layers the OlchedayevLomozov and Cosauti Beds oriented along the Archean-Proterozoic tectonic faults
(6)The geochemical study of RE elements has remarkableimportance in interpretation and restoration of geological
processes of the geological past Because of this it is importantto investigate concentrations of these elements in differentvarieties of rocks of different ages and origins In particular itis important to establish particular paragenetic types betweenRE elements and other associated minerals to solve thegeological genetically problems
(i) to establish correlative links between particular typesof RE elements and particular types of crystalline orsedimentary rocks
(ii) to determine the origin of rocks which contain theseelements (formed in a single magmatic process in acommon metamorphic facies and in a single sedi-mentogenesis cycle)
If the detection of a deposit of zircon and monazite con-taining rare earths brings a direct practical result geochem-ical study of any region of the earth crust is of high particularimportance in geological prospection Because it solves agreat problem regarding the determination of parageneticassociations of minerals and chemical elements to determinethe type of petrographic provinces specifies geotectonicappearance of territories and to determine the links betweenlithogenic processes and palaeogeographic conditions in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Geology Advances in
Advances in Geology 3
platform cover [4] but all such geological deductions haveproved to be arbitrary often subjective and presented more apersonal vision of researchers on the geology of earth crustin this area [5] Also rather approximately had been executedthe geological prospectings in order to solve the perspectiveof detection in the mentioned region of some significantaccumulation of rare earth elements [6]
The proposed study is one of a synthesis of geologicalresults performed by a group of researchers who have workedtogether beginning with the design field research andlaboratory analyses and ending with the generalization ofobtained data In this regard the author presents not onlythe geological vision of this group but also his own conceptconcerning the specificity of rare earths in the region ofMoldovan segment of Dniester basin
2 General Suggestions Concerningthe Geological Structure of the Territory ofthe Republic of Moldova
On the territory of the Republic ofMoldova are distinguishedseveral fragments of some regional structures which in termsof tectonic and geological evolution are different from eachother in a highlighted manner [8]
About two thirds of the territory of the republic falls in asegment of southwest pericratonic zone of the East EuropeanPlatform called by Moldavian and Ukrainian geologists theldquoMoldavian Platerdquo (Figure 1)
A part of south-eastern region is occupied by a fragmentof the Dobrogea Orogen which endorses the typical featuresof a young platform Constituted in late Paleozoic it is con-sidered an epi-Hercynian platform Crystalline basement isconstituted by metamorphosed rocks in lower metamorphicfaces and igneous intrusions and sedimentary cover about500 meters thick is formed by Mesozoic-Cainozoic age strataplaced almost parallel
Another regional structuremdashPredobrogean Depressionwhich extends to the northwest in Romaniamdashis seen bysome researchers [9] as a component part of the EastEuropean Platform At the same time the geological evolutionof this structure and tectonic processes which manifestedthemselves in the Paleozoic and especially in the earlyMesozoic allow considering the Predobrogean Depression anindependent structure with specific geological and structuralfeatures
In the northern and north-eastern regions of the Republicof Moldova (marked area in Figure 1) we can highlightthree geological-structural units crystalline basement sed-imentary cover composed of diverse rocks and Pliocene-Pleistocene formations These three geological-structuralunits in terms of age origin and composition are differentfrom each to other in a cardinal way Due to shallow depthsup to crystalline rocks of the basement and mineralizationwhich contain elements of rare earths discovered in the basallayers of sedimentary cover the central region of the DniesterRiver basin has always made up a remarkable object of studyfor geological research
3 The Petrographic Specificity ofthe Crystalline Basement Rocks
The principle of differentiation of crystalline rocks inmost cases Archean or of early Proterozoic age situatedin the basement composition was and remains a subjectof permanent discussion In geochronological-stratigraphicterms the most appropriate methodological principle in thegeological study of the south-western slope of the EastEuropean Platform is the correlation of ultrametamorphosedcrystalline formations within a regional or local geotectonicunit Basement rocks in the area reflect all the specificfeatures of geological processes that led to the formation ofthe south-western slope of the Ukrainian Crystalline Shieldwhich is situated to the north of the Dniester Faultmdashthemost important geotectonic element from the mentionedregion (Figure 1) Crystalline basement is an agglomeratecomposed of metamorphic ultrametamorphic magmaticand metasomatic rocks of different agesmdashearly Archeanand early Proterozoic In general crystalline formations arepresented in an extremely complicated way but at the sametime there are some distinguishing features that differentiatethis portion of the earth crust from other neighbouring areasAnalyzing the magmatic and ultrametamorphic processeswhich occurred in the Precambrian of Ukrainian CrystallineShield Archean and Proterozoic rocks and can be system-atized in specific formations that differ from each otherby petrographic varieties and physicochemical conditions oftheir formation [10] gneisses and crystalline schists (earlyArchean age) enderbites plagiomigmatites plagiogranites(formed as a result of anatexis processes at the geochrono-logical limit of later Archeanndashearly Proterozoic) alaskitesleucogranites (early Proterozoic age of palingenesis origin)mdashTable 1 Having a predominantly granitic composition thesevarieties of rocks differ from each other only in the auxiliaryindex (accessory mineralizations presence of geochemicalaureoles and geophysical anomalies) It should bementionedthat in the composition of these rocks with rare exceptionspredominate plagioclases (oligoclase-andesine) and almost inall lithological varieties often in significant quantities is alsopresented hypersthene
Is typical associations of accessory minerals consti-tuted from zircon monazite garnet apatite magnetiteand ilmenite which with some exceptions are presentalmost in all petrology varieties It is significant that in theoldest rocks of the gneisses formation (dominate biotite-amphibole-hypersthene plagiogneisses) of early Archean agemonazitemdashone of the most important minerals in geologicalformations of the basement from area that contains rareearthsmdashwas found only occasionally and zircon is found inform of small isolated grains in relatively small quantitiesin almost all varieties of gneisses and crystalline schistsAs an accessory mineral monazite frequently occurs inmineralogical composition of the ultrametamorphic varietiesof enderbite and alaskite formations
We would like to pay attention to the fact the major-ity of zircon grains which are in ultrametamorphic rockscomposition have round forms with melting traces of the
4 Advances in Geology
Table1Precam
briancrystalline
form
ations
inthes
outh-w
estregionof
theU
krainian
Crystalline
Shieldandaccessorym
ineralconcentrations
which
containelem
entsof
REgrou
p(C
entral
region
oftheD
niesterR
iver
basin
)
Num
ber
Form
ations
andcomplexes
ofrockslowast
Agelowast
106years
Petro
graphicv
arietie
sMineralogicalcompo
sition
Accessoriesm
inerals
1Ch
arno
ckitesa
ndgranites
form
ation
Lowe
rProterozoic
(200
0ndash2200)
Alaskite
Quartz(20ndash4
0)
Microcline
(35ndash70)
Plagioclasemdash
Pl20ndash25(5ndash35
)Biotite
(0ndash5)
Zircon
(5ndash2
00gt)
Mon
azite
(30ndash
250g
t)Magnetite(9ndash
4009
gt)
Apatite
(sim14gt)
Garnet(7ndash17gt)
2Leucogranite
Quartz(20ndash35
)Microcline
(5ndash35
)Plagioclasemdash
Pl20ndash25(30ndash
35)
Magnetite(sim20
gt)
Zircon
(656
gt)
Mon
azite
(1270g
t)Ap
atite
(sim20
gt)
3Plagiogranitesa
ndtonalities
form
ation
Upp
erArcheanndashL
ower
Proterozoic
(2550ndash
2800)
Plagiomigmatite
Quartz(20ndash30
)Plagioclasemdash
Pl25ndash30(60ndash
80)
Biotite
(lt10)
Microcline
(lt5
)
Apatitesim
Mon
azite
(12ndash
211g
t)Zircon
(12ndash
190g
t)Garnet(23ndash183
gt)
4Plagiogranite
Quartz(20ndash50
)Plagioclasemdash
Pl25ndash30(35ndash70)
Pyroxene
(5ndash15
)Biotitesim
Microclinesim
Apatite
(10ndash
40gt)
Zircon
(sim10
gt)
Mon
azitesim
Magnetite(200g
t)Ilm
enite
(1430
gt)
5En
derbitesformation
Upp
erArchean
(2850ndash
3150)
Enderbite
Quartz(20ndash30
)Plagioclasemdash
Pl25(50ndash
80)
Pyroxene
mon
oclin
ic(5ndash15
)Hypersth
ene(5ndash20)
Biotite
(lt5
)Microclinesim
Apatite
(228ndash1080g
t)Zircon
(20ndash
30gt)
Mon
azitesim
Ilmenite
(sim658g
t)Magnetite
(3317ndash7550
gt)
6Th
ecom
plex
ofmetam
orph
icrocks
Lower
Archean
(3300ndash
3750)
Biotite-pyroxeneP
lagiogneiss
Quartz(10ndash30
)Plagioclasemdash
Pl30(40ndash
60)
Pyroxene
mon
oclin
ic(5-4)
Hypersth
ene(lt10)
Biotite
(10ndash
15)
Microcline
(lt10)
Apatite
(17ndash680g
t)Zircon
(8ndash6
0)gt
Ilmenite
(sim1000
gt)
Magnetite
(24ndash
1348
gt)
7Biotite-amph
ibole-pyroxene-
plagiocla
sewith
magnetite
crystalline
schist
Plagioclasemdash
Pl30(10ndash
70)
Pyroxene
mon
oclin
ic(sim15)
Hornb
lend
e(sim25)
Biotite
(sim20)
Quartz(lt5
)
Magnetite(5ndash10gt)
Apatite
(sim170g
t)Zircon
(sim20
0gt)
lowast
Accordingto
thes
tratigraph
icschemee
labo
ratedby
theR
egionalStratigraph
icCom
mittee
from
Ukraine1984
Advances in Geology 5
external zones Perhaps because of higher refractory prop-erties this accessory mineral passed from older geologicalformations in the younger ones without essential changesthat are imposed by anatexis and palingenetic processesProbably it also refers to monazite present in the samevarieties of rocks It produces the impression that multipleacts of progressive metamorphism ultrametamorphism andretrograde metamorphism that took place during an enor-mous period of geological time and modified in a cardinalway all petrologic varieties of the platform basement anddid not influence the redistribution in underground spaceof zircon and monazite The above-presented affirmationis supported by geochronological research data achievedthrough the radiological methods by Ukrainian geologists Inthe regions of Ukrainian Crystalline Shield slopemdashadjacentarea of Dniester River basin monazite and zircon in rockcomposition from formations mentioned above practicallyhave one and the same Archean age [11]
Many authors link the formation of concentrations ofRE elements in the Dniester region with the presence ofaccessory monazite and zircon which are present in compo-sition of different petrologic and lithological varieties of lateArchean early Proterozoic and Vendian ages [5] Remarkingthe high correlation coefficient between zircon and monazite(120588 = 073) and satisfactory degree of correlation (120578 =86 gt 3) we can assume that these two minerals interms of geology are syngenetic and probably as accessoryminerals were formed at the same time in one and the samepetrological formation At the same time we would liketo emphasize that monazite in the complex composition ofmetamorphic rocks of early Archaic age practically was notfound On the basis of the data from previous mineralogicaland geochemical researches it was determined that monaziteweight in geochemical aureoles formation (RE-elements) ismuch higher than that of zircon [12] We would like to notethat between crystalline and terrigenous formations in thisarea in quite small quantities can also be found othermineralscontaining rare earths (xenotime and allanite) [10]
Most of rare earth minerals including zircon and mon-azite are constituents of granite and nepheline-syenite peg-matites There are known endogenous deposits of the rareearths which are in geological-genetic relations with alkalinegranites intrusive alkaline ultrabasic rocks syenites (rich inpyrochlore) and pneumatolytic hydrothermal formations Ifwe examine the mineralogical compositions of the meta-morphic and ultrametamorphic rocks varieties in the centralregion of the Dniester River basin we will observe that inthese types of crystalline rocks in no way can form parage-netic associations with minerals which contain rare earths[9] It is possible that accessory mineralization of zircon andmonazite has no directly bearing to the origin of formationsfrom this area but can be part of some blocks of the earthrsquoscrust from neighboring regions For example in differentregions of the Ukrainian Crystalline Shield (Jitomir Vinita)in alkaline granitic and pegmatite rocks with monazite andzircon were found significant concentrations of RE elements(Lanthanum Cerium and Neodymium) [13]
From the above-said results that the issue of mineralsrsquoorigin (especially of zircon andmonazite) which contain rare
earths found in different varieties of crystalline rocks in thesouth-western East European Platform remains open
In terms of fundamental geotectonic concepts the oldestparts of the continental earth crustmdashcrystalline shieldsmdashduring the geologic time underwent several cardinal tectonicmodifications [14] Therefore it is presumed that in thetectonic cycle of theWhite Sea (Archean) the manifestationswhich are well observed in the Baltic Crystalline Shieldformations ended with intensive folding metamorphosingand profound granitization phenomena For correspondinggeological epoch is characteristic the formation of somegranite-gneiss domes delimited in the initial phase by linearzones consisting of volcanogenic-sedimentary rocks Atpresent these linear areas are transformed into relatively nar-row synclinorium formed of profoundly modified rocks indifferent metamorphic facies As a result of the epi-Archeantectonic processes (until early Proterozoic) we can assumethat in such synclinorium took place several epeirogenicmovements of crystalline basement concomitantly accom-panied by various destructive processes Consequently incertain places emerged aulacogens delimited by lineamentswithin which are found many remains of Archean blocksand areas with well-pronounced progressive and retrogrademetamorphism manifestations A similar structure could bethe Dniester Fault which de facto represents a segmentof Podolian Tectonic Faults Zone [15] and which delimitsin the south-western part another crystalline shield of EastEuropean PlatformmdashUkrainian Crystalline Shield Tectonicphenomena of early Proterozoic period ended with theconsolidation of the crystalline basement from region Insubsequent geological periods the tectonic activity graduallyreduced tominimum introducing in theDniester-Prut inter-fluves region only some structural changes genetically linkedto the evolution of Dniester Fault For example in Ripheanaround 950 million years along the Podolian Tectonic FaultsZone in a relatively weak process of continental riftogenesisoccurred alkaline lava flows in the result of which lenticularbodies of diabases were formed
Manifestations of effusive or intrusive magmatism inArchean-early Proterozoic in the central region of the Dni-ester River basin have not been determined It is possible thatultrametamorphic processes that took place in this regionin late Archean-early Proterozoic probably ldquoretouchedrdquo com-pletely initial igneous rocks in the area Consequently we cansay that zircon and monazite in the initial stages of geologic-structural formation of pericratonic region of south-westernpart of East European Platformwere already formed and werepart of the composition of pre-rocks
As mentioned above most endogenous deposits of REare genetically related either with alkaline granites intrusionsor alkaline typical intrusions Examining the contribution ofmagmatism in the evolution of earth crust it is determinedthat the alkaline magmatism events began about 25ndash27billion years ago and in an intensive way developed inPhanerozoic and arrived to maximal action in the MesozoicIn general alkaline rocks older than 27 billion years in theearth crust formations have not been found [16]Thus it maybe deduced that the origin of zircon and monazite detectedin geological formations in Dniester region in no way can be
6 Advances in Geology
linked with alkaline intrusions which may have been formedin the Ukrainian Crystalline Shield
It is obvious that theseminerals were formed however in amagmatic process unexplained so far by geologists interestedin the rare earths in the area and the issue of RE origin incomposition of metamorphic and ultrametamorphic rocksof the crystalline basement in the south-western part ofEast European Platform requires a serious investigation to besolved
There exist industrial concentrations of REminerals bothof endogenous type and metamorfogenic one Rare earthdeposits related tometamorphic formations are characterizedby relatively homogeneous distribution of RE elements onareas of significant extension and are presented in generallyby migmatites gneiss and metamorphosed conglomerateswith monazite of other origin It is not excluded that inthe geological formations of the crystalline basement arepresent accumulations of monazite (and zircon) located inplagiomigmatites and leucogranites which have a rather largedistribution in the Dniester region
4 Sedimentary Formations andDetection Premises of Concentrations ofRare Earths Elements
41 The Types of Hypergen Deposits of Rare Earths ElementsRare earths minerals of exogenous origin until now are notknown At the same time most rare earth deposits exploitedat present are of exogenous type
According to systematization of useful mineral depositstypes [17] hypergen deposits of RE are grouped into threetypes
(1) residual which are formed as a result of alterationof granite syenite nepheline-syenite rocks rich inmonazite sphene pyrochlore thorianite cerianiteand formation in erosion crust of a zone rich with REof cerium subgroup Nb Zr Th and Y
(2) sedimentary-detrital (a) alluvial lands formed fromconcentrations of stable minerals in hypergen zonesuch as monazite ilmenorutile zircon uranothorite(b) eluvium-adobe lands with high concentrationsof xenotime pyrochlore fergusonite thorite and (c)mineral lands of coastal areas consisting of significantaccumulations of monazite ilmenite rutile and zir-con
(3) sedimentary and sedimentary-biogenic (a) phospho-rites (b) sands rich in REminerals (c) shales and (d)fossil reminiscences
Referring to the territory in northern and north-eastern partof Republic of Moldova in the basal layers of sedimentarycover may be present the RE deposits such as detritalsediments This confirms the results of recent geological-geochemical researches carried out in the last decades of thelast century [7 18]
In hypergen areamonazite is a quite stable mineral Beingresistant to the action of exogenous agents it is not broken
down and in the following way in rubbly grains is keptvery long periods of geological timeTherefore the monazitepresent in crystalline rocks of Archean and early Proterozoicage is also found in sedimentary rocks of platform cover in thecentral region of the Dniester River basin Since the specificweight of monazite is quite high (exceeding 50 gcm3) inthe erosion process of rocks with accessory monazite andfurther sedimentogenesis of disintegrated material often areformed mechanical aureoles of this mineral Therefore it isexplained that the monazite in detrital sedimentary layersmay be present in concentrations much higher than itsconcentrations in the syngenetic rocks
For example in a drilling for geological mapping dugin the south of the marked territory in Figure 1 has beendetected a geochemical anomaly with maximum concentra-tions of lanthanum (01) and cerium (008) generated bymonazite the concentration of which in basal layers of thesedimentary cover varies between 05 and 218 gt [10]
In a similar process are also formed the mechanicalaureoles of zircon
Sedimentary cover in central region of the DniesterRiver basin is made up of several complex beds placedalmost horizontally In terms of geochronology of lithologicalcomposition of sedimentation conditions and diageneticprocesses in slope cover of southwestern part of theEast Euro-pean Platform are identified four formations and sedimentaryrock complexes Vendian Formation Ordovician-Silurianstratigraphic Complex Cretaceous Formation and NeogeneFormation (note currently in many countries the name ofstratigraphic unit Vendian is replaced with Ediacaran butin Republic of Moldova so far remain the same names ofstratigraphic units used in Russia)
Ordovician-Silurian beds consisting prevailingly oflimestone-dolomite varieties limestone-siliceous rocks ofCretaceous and diversity of limestone sand and clay varietiesof Neogene age in terms of the problem approached in thischapter unlike the Vendian basal layers of sedimentarycover do not present any practical interest
By direct comparison it was demonstrated that thegeological section of Podolian Vendian is stratotype almostfor all formations of this age opened in different regionsof the East European Platform Thus Vendian age layerssituated in natural cropping or crossed by drilling in the northand north-eastern zone of Republic of Moldova presenta southeastern fragment of Podolian Vendian and in anatural way without assumptions the stratigraphic scheme ofUkrainian geologists can also be applied in the Dniester riverbasin conditions For a rather complete documentation aboutVendian Formation in the region we make reference to aquite ample synthesis work prepared by Ukrainian geologistsforTheThird International Symposium on Cambrian System(Kiev 1990) [19]
42 Camenka Formation Directly on the surface of crys-talline basement are laid-down in the deposit the layersof Camenka Formation constituted of basal conglomeratesand diabases probably of Riphean age The formation body(average thickness about 20 meters) has a lenticular-flat
Advances in Geology 7
The distribution area of Camenka formation
Central region of the Dniester River basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of crystalline basement surface (m)Isopachites of Camenka formation (m)
0 10 20
(km) minus280
minus240
minus160
20
40minus140minus260
minus200
minus180
minus160
minus80
minus80
60
minus60
minus200
minus100minus140 1
0
10
10
10
10
10
20
20
20
20
20
20
20
20
20
20
minus40
minus20
minus20
0
30
0
0
30
30
80
Figure 2 The distribution area of Camenka Formation in the central region of the Dniester River basin [13]
aspect is relatively narrow (8ndash10 kilometers in cross section)is oriented in a north-western direction and covers thelinear-depressive zone of Dniester Fault (Figure 2) We canassume that the centers of lenticular forms coincide withchannels throughwhich on the earth surface poured lavawithalkaline composition specific for early stages of continentalriftogenesisThe phenomenon took place in later Proterozoicin one of the last phases of tectonic activity in south-westernareas of the East European Platform
Camenka Formation consists of diabases and a basal layerof microconglomerates and conglomerates (Soroca Beds)
Lithological varieties of Soroca in the spread region ofFormation Camenka do not present an integral structuralunit Firstly these lithological varieties are in deposits just inthe spread zone of diabases and only in someplaces vulcanitesof Camenka Formation are laid-down directly in depositon the surface of crystalline basement Perhaps Sorocabasal beds in the mentioned region had had a much largespread but because of denudation processes were preservedonly under diabases Thickness of Soroca Beds crossed bydrilling mapping varies from 05 to 35 meters Rocks aredistinguished by their mineralogical composition and areformed from an unselected rubbly material conglomeratesconglomerate-breccias microconglomerates (predominant)coarse-grained sandstones and arkose sandstones (rarely)
The rubbly material is presented by slightly rounded grainsof crystalline basement rocksmdashquartzite potash feldsparand biotite scales cemented with a brown argilitic materialCement volume typically exceeds 50 by volume In thefollowing way most of Soroca Bedsrsquo rocks differ by theirspecific brown color
Arkose sandstones and microconglomerates that can befound in the composition of the basal layers of Camenka For-mation are massive rocks hard of gray-green or pink-graycolor have sabulous structures and consist of plagioclase (upto 50ndash60) potash feldspar (up to 15) quartz (25 to 35)cement and grains of basement rocks
In clastic material are prevalent semirounded or ruggedforms and grainsrsquo sizes range from 10ndash15 millimeters(microconglomerates) 10ndash01 millimeters (sandstones)01 millimeters (sandy mudstones) Cement has a highporosity and has a kaolin-hydromicaceous kaolin-chlorite-hydromicaceous or kaolin composition
From accessory minerals are present small grains ofgarnet zircon monazite apatite and titanomagnetite
The rocks of Soroca Beds have a specific radioactivity rel-atively high (30ndash35 micronshour) imposed by the presenceof isomorphic thorium in the monazite composition
Based on geochemical investigations of Sorocamicrocon-glomerate were found relatively high concentrations of La
8 Advances in Geology
0 10 20
(km)
The morfostructure of Vendian formation
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isopachites of Vendian layers (m)Isohypses of upper limit of the Vendian formation (m)
minus80
minus60
minus40
minus20
minus20
0
0
0
20
20
20
20
40
40
40
40
60
60
60
60
80
80
80
80
100
100
100
120
120
120
140
140
140
160
160
160
180
180
180
180
180
200
200
200
200
200
200
220
220
220
220
220
240
240
240
240
240
260
260
260
280
280
280300
Figure 3 The morphostructure of Vendian Formation in the central region of the Dniester River basin [13]
Diabases predominate in Camenka Formation and inaxial zone of the banded body exceed the thickness of 30ndash40m In macroscopic point of view diabases are compactvolcanogenic rocks of a dark gray gray-brown or darkgreenish color with a relatively high specific weight Theirstructure is cryptocrystalline or crystalline in very smallgrains Between diabases discovered in the Dniester areathere are two varietiesmdashaphyric diabase and diabase withan apparently porphyric texture Usually porphyric inclu-sions have various sizes (1ndash15 millimeters) and consist ofcalcite and rarely chlorite Most diabases have an ophyticstructure and massive texture and in their composition areincluded basic plagioclase (40ndash50) monoclinic pyroxene(5ndash19) chlorite (30ndash35) epidote (3ndash7) and titanomag-netite (5ndash10)Theminerals which contained RE elements inCamenka Formation were not detected
43 Terrigenous Layers from the Vendian Lower LevelAccording to the stratigraphic schemeused byMoldavian andUkrainian geologists [20] the formations of Vendian age aredifferentiated in series which include several beds In normalsequence Moldavian Vendian is composed of OlchedayevBeds (Vol) LomozovBeds (Vlm) Cosauti Beds (Vks) LyadovaBeds (Vld) Bernashevka Beds (Vbrn) Bronnitsa Beds (Vbr)Zincov Beds (Vzn) Dzhurzhevka Beds (Vdz) Kalyus Beds
(Vkl) Pilipy Beds (Vpl) and Shebutintsy Beds (Vsb) Allthese local stratigraphic units are composed of terrigenousvarieties sandstones aleurolites mudstones tuffaceous claystone and greenstones (Table 2)
The majority of layers almost completely can be studiedeither in outcrops in northern part of the republic either inmapping drilling cores dug in areas covered by PaleozoicMesozoic and Cainozoic formations
In the region between Dniester and Prut Rivers Vendianlayers are laid-down directly in deposit on the surface ofcrystalline basement and the central region of Dniester Riverbasinmdashpartially on the Camenka diabases and Volyn Seriesmicroconglomerates
The lower limit of Vendian Formation in the Dniesterriver region has a dipping oriented to southwest (210ndash220∘)and dipping angle varies around the 401015840 (Figure 3) It shouldbe mentioned that the basement relief can be observed ingeomorphologic elements that are in direct connection withthe principal faults in the Dniester region The upper limitof Vendian Formation in the Podolian Tectonic Zone with asmall dipping to southndashsouth-western is disposed practicallyhorizontally and in the south-western of mentioned territoryin this chapter the lower limit is the same direction southndashsouth-western dipping with an angle about 201015840ndash301015840 By thissmall difference between the dipping angles of geological
Advances in Geology 9
Table2Ve
ndianageb
edsinthec
entralregion
oftheD
niesterR
iver
basin
Serie
sFo
rmations
Theb
eds(localstratigraph
icindices)
microfossilsv
arieties
(thickn
essinmeters)
Thea
verage
concentrations
ofΣRE
(La+
Ce+
Y)lowast
gt
dataarefrom
[7]
Kanilovka
Danilo
vka
Vdn
ShebutintsyB
eds(V
sb)mud
stonesa
ndbrow
nandredd
ish-brownaleurolites
with
sand
stone
intercalationsK
aniloviainsolatia
AJistVend
otaeniaantiq
uaGn
il(17ndash43
m)
54
Pilip
yBe
ds(V
pl)mud
stonesa
ndgreenish
gray
aleurolites
with
sand
stone
intercalations
Vend
otaeniaantiq
uaGn
il(18ndash38
m)
45
Mogilev-Po
dolsk
y
Nagoryany
Vng
Kalyu
sBeds(V
kl)dark
gray
with
brow
nnu
ance
mud
stonesph
osph
oriticc
oncretionscarbo
nate
inclu
sions
with
cone-in
-con
etextureV
endotaeniaantiq
uaGn
ilFu
sosqua
mulaAss
Pilitela
Ass
(55ndash80
m)
58
Dzhurzhevka
Beds
(Vdz)sand
stone
rhythm
icstratifi
catio
nsaleurolitesa
ndmud
stones
Nemiana
simplex
PalVend
otaeniaantiq
uaGn
il(10ndash
25m)
53
Jaryshev
Vjr
Zincov
Beds
(Vzn)mud
stonesrhythmicstratifi
catio
nswith
aleurolitessandstone
intercalations
(15ndash20
m)
60
Bron
nitsaB
eds(V
br)mud
stonesa
ndtuffaceou
sclaystonesgreenstonesw
ithmottledmud
stone
intercalationsB
ronicella
podolicaZa
ica-N
ov(20ndash25m
)64
Bernashe
vkaB
eds(V
brn)sandstonesw
ithmud
stone
intercalationsT
irasia
nadiscifarm
isPa
lEo
holin
iamasquensis
Gnill(5ndash20
m)
67
Mogilev
Vmg
Lyad
ovaB
eds(V
ld)mud
stonesa
ndgreensand
yaleurolitesgreensto
nesredd
ishtuffaceou
scla
ystonesin
theu
pper
levelsmdash
sand
stone
intercalationsLjadova
perjo
rata
Ass(20ndash
25m)
38
Cosau
tiBe
ds(V
ks)sand
stonesw
ithrare
gritstone
intercalations
andaleurolitesN
emiana
simplex
Pal(10ndash
18m)
65
Lomozov
Beds
(Vlm)mud
stonesw
ithaleurolites
andsand
stone
intercalations(0ndash
8m)
94Olcheda
yevB
eds(V
ol)theu
pper
levelsmdash
sand
stone
with
aleurolites
intercalationsthe
lower
levelsmdash
gritstone
with
desand
stone
insm
allsgrains
andmud
stone
intercalations(10ndash35m
)72
Volyn
Camenka
R()
Greenish
gray
aphyric
Diaba
sesw
itham
ygdaleform
impregnatio
nsof
plagiocla
se(1ndash
35m)
Soroca
Bedscon
glom
eratesm
icrocong
lomeratesarkoses
andstones(0ndash
10m)
AR-PR
1Cr
ystalline
basementrocksgneiss
escrystallin
eschistsplagiogranitesplagiomigmatites
enderbitesleucogranitesalaskites
lowast
Incompleted
atao
fspectrographica
nalysisthe
northern
partof
marketterritoryin
theF
igure1
10 Advances in Geology
limits is explained the slow increase of the thickness ofVendian Formation that in immediate nearness of Predo-brogean Depression exceeds 750ndash800 meters In contrastwith lower limit the surface of upper limit of Vendian wassubjected to relatively poor processes of denudation whichchanged the morphostructural aspect appeared after the endof sedimentogenesis processes
As a result of geochemical investigations it was estab-lished that in the lower layers of Vendian Formation theconcentration of RE elements compared with layers of upperlevels is relatively higher (Table 2) In particular it refers toOlchedayev Lomozov and Cosauti Beds of Mogilev Forma-tion For example in the southern part of the territory inOlchedayev Beds was detected an anomalous zone with quitehigh concentrations 119862La = 01 and 119862Ce = 008 [10] whichexceed the geochemical background that is approximately thesame as for Lanthanum and for Cerium
In terms of perspective of detecting some significantconcentrations of RE elements as a result of formationof mechanical aureoles consisting of zircon and mon-azite Olchedayev Lomozov and Cosauti beds represent anobject for much more detailed geological and geochemicalresearches
Olchedayev beds are composed by detrital sedimentaryrocks in big grains (varieties of conglomerates microcon-glomerates and sandstones) and mudstones or sandy mud-stones present in the layerrsquos body in form of relatively shallowintercalations
Geological section of Olchedayev beds is not stablethroughout the whole distribution area but in terms oflithological varieties which form layers and the complexstratifications of this local stratigraphic unit it is observed arelatively constant accordance in the lower levels are presentmicroconglomerates and in the upper onesmdashgritstone inbig grains Specific for Olchedayev layers is the presenceof a layer of clays and sandy clays which separate themicroconglomerates from gritstone
Geological section of Olchedayev beds constructed onbasis of mapping drillings in the southern part of the markedterritory in Figure 1 is presented in the following way
Directly on the altered surface of diabases of CamenkaFormation or on crystalline basement surface crust practi-cally devoid of erosion crust are laid-down
(1) Microconglomerates of brown color with angulargrains of quartz potash feldspar and diabases (up to20ndash25) the color is imposed by clayish cement richin iron hydroxides the thickness of this basal layervaries around 4 meters
(2) Rhythmic intercalations of arkose microconglomer-ates with sandstones in various grain of gray or gray-green color in both lithological varieties are presentinclusions of sandy clay stones and clay stones layerthicknessmdashabout 7 meters
(3) Dark gray microconglomerates with clastic grainsof quartz and potash feldspar microconglomeratecement is clayish and their thickness is 1 meter
(4) Greenish-brown and brown mudstones with thinintercalations of fines sandstone and sandy clay stonethickness 45 meters
(5) Gray and gray-reddish arkose gritstones with isolatedinclusions of quartz and potash feldspar (some grainsreach up to 5 millimeters in diameter) between thesandstones are found rare and thin intercalationsof dark gray mudstones thickness average about 7meters
(6) Gritstones of dark gray color with clayish cementthickness not exceeding 4 meters
(7) Quartz-feldspar gray and light gray sandstones indifferent grain including coarse grains are visiblehorizontal and oblique stratifications of differentgranular fractions sandstone thickness 50 meterson the quartz-feldspar sandstones are laid-down theLomozov Beds
The most common thickness of Olchedayev layers variesaround 25 meters
Sandstones and gritstones of Olchedayev Beds in theupper regions of geological section are of light gray colorIn lower areas depending on potash feldspar quantitiesthe color has reddish hues In microscopic sections areobserved sabulous silitic or mixed structures (sabulous-silitic) cement structure is silitic In terms of compositionthe rocks range from quartzose and arkose varieties Amountof feldspars (potash feldspar prevailed) in most cases doesnot exceed 50 by volume Both in the microconglomerates(also highlighted) and in the sandstones are frequent isolatedgrains of quartzite and rocks of crystalline basement In thelower levels of Olchedayev layers are found frequently smallscales of biotite
The degree of grains rounding from which are formedthe terrigenous rocks varieties of Olchedayev increases withtheir size coarse grains are round and smooth small grainsare ragged Often microconglomerates cement is amorphousmass clayish which together with rock grains imposedporosity quite evident
Accessory minerals in small quantities are presented bygarnet zircon and monazite A minus of geological researchcarried out in the mentioned region in this chapter consistedin that a mineralogical analysis which would determine thequantitative relations between zircon and monazite was notachieved As we have remarked the origin of mineralizationrich in RE elements in geological formations from the Dni-ester basin region is a great problem Additional informationwhich would facilitate the solving of this problem wouldpresent the thorough study of the separate grains of zirconandmonazite from the structure and composition andwouldbe extremely important in terms of geochronology It ispossible that the absolute ages of zircon and monazite shouldcoincide with the ages of these minerals found in crystallineformations of basement It did not exclude the case that theseminerals are different as assortment of isomorphic elementsin their chemical composition Such research are importantfor solving of various fundamental and practical geologicalproblems which can determine the origin of zircon and
Advances in Geology 11
monazite the sedimentogenes processes and the formationof mechanical aureoles with significant concentrations ofuseful components Unfortunately because of changes thathave intervened in the last decade of the past century in theRepublic of Moldova all expensive geological research wassuspended
In the Olchedayev rocks are found rare impregnationsof galena barite fluorite and xenotime (YPO
4) Because
monazite and zircon are contained isomorphic impurities ofTh and U and xenotimemdashabout 5 UO
2mdashOlchedayev Beds
are characterized by a relatively high radioactivity whichrarely reaches up to 500 and 780 micronshour
Lomozov beds are formed preponderant frommudstonesa dark gray color with mica they are intercalations ofsandstones finely dispersed The layers thickness has notbeen exceeding 5 meters In some places Lomozov rocks aremissing At level of Lomozov Beds is identified a complexlayer composed of very fine stratifications of fine-grainedsandstone and of dark gray mudstones relatively rich inminerals containingRE Because the average concentration ofLa + Ce + Y amount compared to other Vendian stratifica-tions is the largestmdash94 gt (Table 2)
The mudstones consisted of an amorphous mass ofgray color and in microscopic sections brown color withabundant additions of small scales of hydromica disposedparallel with surfaces of sedimentation On the fund of thisbasedmass are detected small granules (silitic) of quartz withangular forms In Lomozov Beds have a specific character inthe mudstones composition are often presented inclusions ofbiotite and more rarely of muscovite as elongated scales
Cosauti Beds in lithological point of view of this localstratigraphic unit are relatively homogeneous and are com-posed almost solely of sandstone Dark mudstone interca-lations and dispersed fine sandstone are marked only inpatches Cosauti sandstones have white color with sugaraspect in a homogeneous medium or small grain
In microscopic sections sandstones are psammitic clearstructure Aleurite fraction (01 millimeters) is about 5by rock volume (rarelymdash10ndash12) Large grains of quartzare frequent (about 2 millimeters) embedded in argillite-sandy mass (a few tenths of a percent) but in granulometricpoint of view sandstone are very well sorted In the Cosautibeds were discovered sandstone consist not only of quartzgrains Quartzose varieties usually contain about 10 ofdetrital material consisting of other minerals The quartz-feldspar and arkose sandstones are predominated in whichthe feldspar grains scant of above 20 (potassium feldsparis prevailing) It is common inclusions of biotite in the formof scales about 1-2 from volume Less commonly in therock small granules of quartzite are found In small isolatedgranules can be identified pyrite and magnetite Accessoryminerals are more frequent in zircon and monazite whichgenerated geochemical anomalies with relatively high con-centrations of REE
Cement of Cosauti sandstones is relatively variedchlorite-hydromicaceous (sometimes with added of kaolin ordikkite) silica or carbonated in which predominated calciteThe thickness of Cosauti Beds varies between 10 and 18meters
Compared with Olchedayev and Lomozov Beds variedby mineralogical and granulometric composition Vendiansection above Cosauti sandstones are relatively homogeneouson all distribution area A certain practical interest wouldpresent the mudstones of Kalyus Beds rich in phosphoriticconcretions
The morphostructure of Olchedayev Lomozov andCosauti beds succession (Vol + Vlm + Vks) in the Dniesterregion are presented quite homogeneous In terms oftectonic the main structural element within the mentionedterritory in this paper are presented by a segment of PodolianFaults Zone oriented in north-western direction and calledby autochthon geologists Dniester Fault (Figure 1) Effusionmagmatism with alkaline lava flows were distinguished thebeginning of a continental riftogenesis which was manifestedin later Proterozoic As a result of geological mapping ithas been shown that the basement along the Dniester Riverhas a narrow linear structure with typical features of riftvalley in which vertical dislocations amplitudes of basementblocks varies within 20ndash60m [2 3 7 10 18] Completed bythe Camenka diabase this structure in sedimentary coverlayers does not reflect practically anything This is observedby comparison of the crystalline basement relief shown inFigure 2 with the surface of lower limit of Vendian Formation(Figure 4) the latter being much smoother The crystallinebasement relief and the surface of lower limit of VendianFormation are observed linear zones oriented in transversaldirections Dniester Fault which occurred in result of thetectonic process much earliermdashin the south-west of pericra-tonic zone of the East European Platform late Archean wasformed a several tectonic faults oriented in preponderantlynorth-eastern direction [10] Perhaps along these faults hadoccurred more intensive erosion processes that had been ledto digging in the Archean relief negative linear forms
In the following way is explained the morphostructuralaspect of the succession beds which are at Vendian basedin the central region of the Dniester River basin Examiningthe summary thickness of Olchedayev Lomozov andCosautiBeds we see a series of relatively isometric areas whichhave comparatively larger thickness which is in correlationwith some earlier faults (Archean) in the region (Figure 4)Accordingly we conclude that the geological research indetection purpose of eventual essential accumulation of REelements should be continued in these areas with relativelylarger thickness of Vendian basal layers
5 Conclusion
(1) As a result of geological mapping in the basal layersof Moldavian Vendian at accessible depths for an eventualexploitation has been located REE mineralization At thesame time the prospect of these layers in the detection pointof view of some industrial accumulations of ores so far nothas been resolved Consequently in the opinion of manyexplorers studying of Vendian rocks needs to be continueduntil getting a univocal solution
(2) In terms of the geological formations of the centralregion of the Dniester river basin the minerals presenteda practical interest in terms of the formation of significant
12 Advances in Geology
0 10 20
(km)
The lower layers of platform cover
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of lower limit of the Vendian formation (m)
Distribution area of Camenka formation
minus160 minus120
minus140
minus80
minus80
minus60
minus40
0
20
30
30
30
40
40
40
40
40
40
40
40
40
50
50
50
50
50
50
50
60
60
60
60
60
80
Olchedayev-Vol Lomozov-Vlm Cosauti-Vks
Isopachites of lower Vendian layers (Vol + Vlm + Vks ) (m)
Figure 4 The lower layers of platform cover Olchedayev (Vol) Lomozov (Vlm) and Cosauti (Vks) Beds in the central region of the DniesterRiver basin [13]
accumulation of RE elements (Sc Y La Ce and Yb) aremonazite (phosphate) and zircon (silicate) probably zirconand monazite are paragenetically associated
(3) In order to locate in the underground space geo-chemical aureoles of the elements mentioned above it isnecessary to study carefully the conditions of migration andconcentration of these elements in diverse mineralogenesprocesses in conditions of the Dniester River basinmdashin theprogressive and retrograde metamorphism ultrametamor-phism metasomatic processes and training processes of thebasal layers of platform cover
(4) Based on the geological and geochemical data accu-mulated in the geological mapping to outline geochemicalaureoles and anomalies which may serve as a direct indexof the presence in crystalline and sedimentary formations ofmechanical aureoles of monazite and (or) zircon
(5) Geological research in detection purpose of eventualessential accumulation of RE elements in central region ofthe Dniester River basin should be continued in relativelylarger thickness of Vendian basal layers the OlchedayevLomozov and Cosauti Beds oriented along the Archean-Proterozoic tectonic faults
(6)The geochemical study of RE elements has remarkableimportance in interpretation and restoration of geological
processes of the geological past Because of this it is importantto investigate concentrations of these elements in differentvarieties of rocks of different ages and origins In particular itis important to establish particular paragenetic types betweenRE elements and other associated minerals to solve thegeological genetically problems
(i) to establish correlative links between particular typesof RE elements and particular types of crystalline orsedimentary rocks
(ii) to determine the origin of rocks which contain theseelements (formed in a single magmatic process in acommon metamorphic facies and in a single sedi-mentogenesis cycle)
If the detection of a deposit of zircon and monazite con-taining rare earths brings a direct practical result geochem-ical study of any region of the earth crust is of high particularimportance in geological prospection Because it solves agreat problem regarding the determination of parageneticassociations of minerals and chemical elements to determinethe type of petrographic provinces specifies geotectonicappearance of territories and to determine the links betweenlithogenic processes and palaeogeographic conditions in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
Submit your manuscripts athttpwwwhindawicom
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GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Advances in
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Geology Advances in
4 Advances in Geology
Table1Precam
briancrystalline
form
ations
inthes
outh-w
estregionof
theU
krainian
Crystalline
Shieldandaccessorym
ineralconcentrations
which
containelem
entsof
REgrou
p(C
entral
region
oftheD
niesterR
iver
basin
)
Num
ber
Form
ations
andcomplexes
ofrockslowast
Agelowast
106years
Petro
graphicv
arietie
sMineralogicalcompo
sition
Accessoriesm
inerals
1Ch
arno
ckitesa
ndgranites
form
ation
Lowe
rProterozoic
(200
0ndash2200)
Alaskite
Quartz(20ndash4
0)
Microcline
(35ndash70)
Plagioclasemdash
Pl20ndash25(5ndash35
)Biotite
(0ndash5)
Zircon
(5ndash2
00gt)
Mon
azite
(30ndash
250g
t)Magnetite(9ndash
4009
gt)
Apatite
(sim14gt)
Garnet(7ndash17gt)
2Leucogranite
Quartz(20ndash35
)Microcline
(5ndash35
)Plagioclasemdash
Pl20ndash25(30ndash
35)
Magnetite(sim20
gt)
Zircon
(656
gt)
Mon
azite
(1270g
t)Ap
atite
(sim20
gt)
3Plagiogranitesa
ndtonalities
form
ation
Upp
erArcheanndashL
ower
Proterozoic
(2550ndash
2800)
Plagiomigmatite
Quartz(20ndash30
)Plagioclasemdash
Pl25ndash30(60ndash
80)
Biotite
(lt10)
Microcline
(lt5
)
Apatitesim
Mon
azite
(12ndash
211g
t)Zircon
(12ndash
190g
t)Garnet(23ndash183
gt)
4Plagiogranite
Quartz(20ndash50
)Plagioclasemdash
Pl25ndash30(35ndash70)
Pyroxene
(5ndash15
)Biotitesim
Microclinesim
Apatite
(10ndash
40gt)
Zircon
(sim10
gt)
Mon
azitesim
Magnetite(200g
t)Ilm
enite
(1430
gt)
5En
derbitesformation
Upp
erArchean
(2850ndash
3150)
Enderbite
Quartz(20ndash30
)Plagioclasemdash
Pl25(50ndash
80)
Pyroxene
mon
oclin
ic(5ndash15
)Hypersth
ene(5ndash20)
Biotite
(lt5
)Microclinesim
Apatite
(228ndash1080g
t)Zircon
(20ndash
30gt)
Mon
azitesim
Ilmenite
(sim658g
t)Magnetite
(3317ndash7550
gt)
6Th
ecom
plex
ofmetam
orph
icrocks
Lower
Archean
(3300ndash
3750)
Biotite-pyroxeneP
lagiogneiss
Quartz(10ndash30
)Plagioclasemdash
Pl30(40ndash
60)
Pyroxene
mon
oclin
ic(5-4)
Hypersth
ene(lt10)
Biotite
(10ndash
15)
Microcline
(lt10)
Apatite
(17ndash680g
t)Zircon
(8ndash6
0)gt
Ilmenite
(sim1000
gt)
Magnetite
(24ndash
1348
gt)
7Biotite-amph
ibole-pyroxene-
plagiocla
sewith
magnetite
crystalline
schist
Plagioclasemdash
Pl30(10ndash
70)
Pyroxene
mon
oclin
ic(sim15)
Hornb
lend
e(sim25)
Biotite
(sim20)
Quartz(lt5
)
Magnetite(5ndash10gt)
Apatite
(sim170g
t)Zircon
(sim20
0gt)
lowast
Accordingto
thes
tratigraph
icschemee
labo
ratedby
theR
egionalStratigraph
icCom
mittee
from
Ukraine1984
Advances in Geology 5
external zones Perhaps because of higher refractory prop-erties this accessory mineral passed from older geologicalformations in the younger ones without essential changesthat are imposed by anatexis and palingenetic processesProbably it also refers to monazite present in the samevarieties of rocks It produces the impression that multipleacts of progressive metamorphism ultrametamorphism andretrograde metamorphism that took place during an enor-mous period of geological time and modified in a cardinalway all petrologic varieties of the platform basement anddid not influence the redistribution in underground spaceof zircon and monazite The above-presented affirmationis supported by geochronological research data achievedthrough the radiological methods by Ukrainian geologists Inthe regions of Ukrainian Crystalline Shield slopemdashadjacentarea of Dniester River basin monazite and zircon in rockcomposition from formations mentioned above practicallyhave one and the same Archean age [11]
Many authors link the formation of concentrations ofRE elements in the Dniester region with the presence ofaccessory monazite and zircon which are present in compo-sition of different petrologic and lithological varieties of lateArchean early Proterozoic and Vendian ages [5] Remarkingthe high correlation coefficient between zircon and monazite(120588 = 073) and satisfactory degree of correlation (120578 =86 gt 3) we can assume that these two minerals interms of geology are syngenetic and probably as accessoryminerals were formed at the same time in one and the samepetrological formation At the same time we would liketo emphasize that monazite in the complex composition ofmetamorphic rocks of early Archaic age practically was notfound On the basis of the data from previous mineralogicaland geochemical researches it was determined that monaziteweight in geochemical aureoles formation (RE-elements) ismuch higher than that of zircon [12] We would like to notethat between crystalline and terrigenous formations in thisarea in quite small quantities can also be found othermineralscontaining rare earths (xenotime and allanite) [10]
Most of rare earth minerals including zircon and mon-azite are constituents of granite and nepheline-syenite peg-matites There are known endogenous deposits of the rareearths which are in geological-genetic relations with alkalinegranites intrusive alkaline ultrabasic rocks syenites (rich inpyrochlore) and pneumatolytic hydrothermal formations Ifwe examine the mineralogical compositions of the meta-morphic and ultrametamorphic rocks varieties in the centralregion of the Dniester River basin we will observe that inthese types of crystalline rocks in no way can form parage-netic associations with minerals which contain rare earths[9] It is possible that accessory mineralization of zircon andmonazite has no directly bearing to the origin of formationsfrom this area but can be part of some blocks of the earthrsquoscrust from neighboring regions For example in differentregions of the Ukrainian Crystalline Shield (Jitomir Vinita)in alkaline granitic and pegmatite rocks with monazite andzircon were found significant concentrations of RE elements(Lanthanum Cerium and Neodymium) [13]
From the above-said results that the issue of mineralsrsquoorigin (especially of zircon andmonazite) which contain rare
earths found in different varieties of crystalline rocks in thesouth-western East European Platform remains open
In terms of fundamental geotectonic concepts the oldestparts of the continental earth crustmdashcrystalline shieldsmdashduring the geologic time underwent several cardinal tectonicmodifications [14] Therefore it is presumed that in thetectonic cycle of theWhite Sea (Archean) the manifestationswhich are well observed in the Baltic Crystalline Shieldformations ended with intensive folding metamorphosingand profound granitization phenomena For correspondinggeological epoch is characteristic the formation of somegranite-gneiss domes delimited in the initial phase by linearzones consisting of volcanogenic-sedimentary rocks Atpresent these linear areas are transformed into relatively nar-row synclinorium formed of profoundly modified rocks indifferent metamorphic facies As a result of the epi-Archeantectonic processes (until early Proterozoic) we can assumethat in such synclinorium took place several epeirogenicmovements of crystalline basement concomitantly accom-panied by various destructive processes Consequently incertain places emerged aulacogens delimited by lineamentswithin which are found many remains of Archean blocksand areas with well-pronounced progressive and retrogrademetamorphism manifestations A similar structure could bethe Dniester Fault which de facto represents a segmentof Podolian Tectonic Faults Zone [15] and which delimitsin the south-western part another crystalline shield of EastEuropean PlatformmdashUkrainian Crystalline Shield Tectonicphenomena of early Proterozoic period ended with theconsolidation of the crystalline basement from region Insubsequent geological periods the tectonic activity graduallyreduced tominimum introducing in theDniester-Prut inter-fluves region only some structural changes genetically linkedto the evolution of Dniester Fault For example in Ripheanaround 950 million years along the Podolian Tectonic FaultsZone in a relatively weak process of continental riftogenesisoccurred alkaline lava flows in the result of which lenticularbodies of diabases were formed
Manifestations of effusive or intrusive magmatism inArchean-early Proterozoic in the central region of the Dni-ester River basin have not been determined It is possible thatultrametamorphic processes that took place in this regionin late Archean-early Proterozoic probably ldquoretouchedrdquo com-pletely initial igneous rocks in the area Consequently we cansay that zircon and monazite in the initial stages of geologic-structural formation of pericratonic region of south-westernpart of East European Platformwere already formed and werepart of the composition of pre-rocks
As mentioned above most endogenous deposits of REare genetically related either with alkaline granites intrusionsor alkaline typical intrusions Examining the contribution ofmagmatism in the evolution of earth crust it is determinedthat the alkaline magmatism events began about 25ndash27billion years ago and in an intensive way developed inPhanerozoic and arrived to maximal action in the MesozoicIn general alkaline rocks older than 27 billion years in theearth crust formations have not been found [16]Thus it maybe deduced that the origin of zircon and monazite detectedin geological formations in Dniester region in no way can be
6 Advances in Geology
linked with alkaline intrusions which may have been formedin the Ukrainian Crystalline Shield
It is obvious that theseminerals were formed however in amagmatic process unexplained so far by geologists interestedin the rare earths in the area and the issue of RE origin incomposition of metamorphic and ultrametamorphic rocksof the crystalline basement in the south-western part ofEast European Platform requires a serious investigation to besolved
There exist industrial concentrations of REminerals bothof endogenous type and metamorfogenic one Rare earthdeposits related tometamorphic formations are characterizedby relatively homogeneous distribution of RE elements onareas of significant extension and are presented in generallyby migmatites gneiss and metamorphosed conglomerateswith monazite of other origin It is not excluded that inthe geological formations of the crystalline basement arepresent accumulations of monazite (and zircon) located inplagiomigmatites and leucogranites which have a rather largedistribution in the Dniester region
4 Sedimentary Formations andDetection Premises of Concentrations ofRare Earths Elements
41 The Types of Hypergen Deposits of Rare Earths ElementsRare earths minerals of exogenous origin until now are notknown At the same time most rare earth deposits exploitedat present are of exogenous type
According to systematization of useful mineral depositstypes [17] hypergen deposits of RE are grouped into threetypes
(1) residual which are formed as a result of alterationof granite syenite nepheline-syenite rocks rich inmonazite sphene pyrochlore thorianite cerianiteand formation in erosion crust of a zone rich with REof cerium subgroup Nb Zr Th and Y
(2) sedimentary-detrital (a) alluvial lands formed fromconcentrations of stable minerals in hypergen zonesuch as monazite ilmenorutile zircon uranothorite(b) eluvium-adobe lands with high concentrationsof xenotime pyrochlore fergusonite thorite and (c)mineral lands of coastal areas consisting of significantaccumulations of monazite ilmenite rutile and zir-con
(3) sedimentary and sedimentary-biogenic (a) phospho-rites (b) sands rich in REminerals (c) shales and (d)fossil reminiscences
Referring to the territory in northern and north-eastern partof Republic of Moldova in the basal layers of sedimentarycover may be present the RE deposits such as detritalsediments This confirms the results of recent geological-geochemical researches carried out in the last decades of thelast century [7 18]
In hypergen areamonazite is a quite stable mineral Beingresistant to the action of exogenous agents it is not broken
down and in the following way in rubbly grains is keptvery long periods of geological timeTherefore the monazitepresent in crystalline rocks of Archean and early Proterozoicage is also found in sedimentary rocks of platform cover in thecentral region of the Dniester River basin Since the specificweight of monazite is quite high (exceeding 50 gcm3) inthe erosion process of rocks with accessory monazite andfurther sedimentogenesis of disintegrated material often areformed mechanical aureoles of this mineral Therefore it isexplained that the monazite in detrital sedimentary layersmay be present in concentrations much higher than itsconcentrations in the syngenetic rocks
For example in a drilling for geological mapping dugin the south of the marked territory in Figure 1 has beendetected a geochemical anomaly with maximum concentra-tions of lanthanum (01) and cerium (008) generated bymonazite the concentration of which in basal layers of thesedimentary cover varies between 05 and 218 gt [10]
In a similar process are also formed the mechanicalaureoles of zircon
Sedimentary cover in central region of the DniesterRiver basin is made up of several complex beds placedalmost horizontally In terms of geochronology of lithologicalcomposition of sedimentation conditions and diageneticprocesses in slope cover of southwestern part of theEast Euro-pean Platform are identified four formations and sedimentaryrock complexes Vendian Formation Ordovician-Silurianstratigraphic Complex Cretaceous Formation and NeogeneFormation (note currently in many countries the name ofstratigraphic unit Vendian is replaced with Ediacaran butin Republic of Moldova so far remain the same names ofstratigraphic units used in Russia)
Ordovician-Silurian beds consisting prevailingly oflimestone-dolomite varieties limestone-siliceous rocks ofCretaceous and diversity of limestone sand and clay varietiesof Neogene age in terms of the problem approached in thischapter unlike the Vendian basal layers of sedimentarycover do not present any practical interest
By direct comparison it was demonstrated that thegeological section of Podolian Vendian is stratotype almostfor all formations of this age opened in different regionsof the East European Platform Thus Vendian age layerssituated in natural cropping or crossed by drilling in the northand north-eastern zone of Republic of Moldova presenta southeastern fragment of Podolian Vendian and in anatural way without assumptions the stratigraphic scheme ofUkrainian geologists can also be applied in the Dniester riverbasin conditions For a rather complete documentation aboutVendian Formation in the region we make reference to aquite ample synthesis work prepared by Ukrainian geologistsforTheThird International Symposium on Cambrian System(Kiev 1990) [19]
42 Camenka Formation Directly on the surface of crys-talline basement are laid-down in the deposit the layersof Camenka Formation constituted of basal conglomeratesand diabases probably of Riphean age The formation body(average thickness about 20 meters) has a lenticular-flat
Advances in Geology 7
The distribution area of Camenka formation
Central region of the Dniester River basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of crystalline basement surface (m)Isopachites of Camenka formation (m)
0 10 20
(km) minus280
minus240
minus160
20
40minus140minus260
minus200
minus180
minus160
minus80
minus80
60
minus60
minus200
minus100minus140 1
0
10
10
10
10
10
20
20
20
20
20
20
20
20
20
20
minus40
minus20
minus20
0
30
0
0
30
30
80
Figure 2 The distribution area of Camenka Formation in the central region of the Dniester River basin [13]
aspect is relatively narrow (8ndash10 kilometers in cross section)is oriented in a north-western direction and covers thelinear-depressive zone of Dniester Fault (Figure 2) We canassume that the centers of lenticular forms coincide withchannels throughwhich on the earth surface poured lavawithalkaline composition specific for early stages of continentalriftogenesisThe phenomenon took place in later Proterozoicin one of the last phases of tectonic activity in south-westernareas of the East European Platform
Camenka Formation consists of diabases and a basal layerof microconglomerates and conglomerates (Soroca Beds)
Lithological varieties of Soroca in the spread region ofFormation Camenka do not present an integral structuralunit Firstly these lithological varieties are in deposits just inthe spread zone of diabases and only in someplaces vulcanitesof Camenka Formation are laid-down directly in depositon the surface of crystalline basement Perhaps Sorocabasal beds in the mentioned region had had a much largespread but because of denudation processes were preservedonly under diabases Thickness of Soroca Beds crossed bydrilling mapping varies from 05 to 35 meters Rocks aredistinguished by their mineralogical composition and areformed from an unselected rubbly material conglomeratesconglomerate-breccias microconglomerates (predominant)coarse-grained sandstones and arkose sandstones (rarely)
The rubbly material is presented by slightly rounded grainsof crystalline basement rocksmdashquartzite potash feldsparand biotite scales cemented with a brown argilitic materialCement volume typically exceeds 50 by volume In thefollowing way most of Soroca Bedsrsquo rocks differ by theirspecific brown color
Arkose sandstones and microconglomerates that can befound in the composition of the basal layers of Camenka For-mation are massive rocks hard of gray-green or pink-graycolor have sabulous structures and consist of plagioclase (upto 50ndash60) potash feldspar (up to 15) quartz (25 to 35)cement and grains of basement rocks
In clastic material are prevalent semirounded or ruggedforms and grainsrsquo sizes range from 10ndash15 millimeters(microconglomerates) 10ndash01 millimeters (sandstones)01 millimeters (sandy mudstones) Cement has a highporosity and has a kaolin-hydromicaceous kaolin-chlorite-hydromicaceous or kaolin composition
From accessory minerals are present small grains ofgarnet zircon monazite apatite and titanomagnetite
The rocks of Soroca Beds have a specific radioactivity rel-atively high (30ndash35 micronshour) imposed by the presenceof isomorphic thorium in the monazite composition
Based on geochemical investigations of Sorocamicrocon-glomerate were found relatively high concentrations of La
8 Advances in Geology
0 10 20
(km)
The morfostructure of Vendian formation
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isopachites of Vendian layers (m)Isohypses of upper limit of the Vendian formation (m)
minus80
minus60
minus40
minus20
minus20
0
0
0
20
20
20
20
40
40
40
40
60
60
60
60
80
80
80
80
100
100
100
120
120
120
140
140
140
160
160
160
180
180
180
180
180
200
200
200
200
200
200
220
220
220
220
220
240
240
240
240
240
260
260
260
280
280
280300
Figure 3 The morphostructure of Vendian Formation in the central region of the Dniester River basin [13]
Diabases predominate in Camenka Formation and inaxial zone of the banded body exceed the thickness of 30ndash40m In macroscopic point of view diabases are compactvolcanogenic rocks of a dark gray gray-brown or darkgreenish color with a relatively high specific weight Theirstructure is cryptocrystalline or crystalline in very smallgrains Between diabases discovered in the Dniester areathere are two varietiesmdashaphyric diabase and diabase withan apparently porphyric texture Usually porphyric inclu-sions have various sizes (1ndash15 millimeters) and consist ofcalcite and rarely chlorite Most diabases have an ophyticstructure and massive texture and in their composition areincluded basic plagioclase (40ndash50) monoclinic pyroxene(5ndash19) chlorite (30ndash35) epidote (3ndash7) and titanomag-netite (5ndash10)Theminerals which contained RE elements inCamenka Formation were not detected
43 Terrigenous Layers from the Vendian Lower LevelAccording to the stratigraphic schemeused byMoldavian andUkrainian geologists [20] the formations of Vendian age aredifferentiated in series which include several beds In normalsequence Moldavian Vendian is composed of OlchedayevBeds (Vol) LomozovBeds (Vlm) Cosauti Beds (Vks) LyadovaBeds (Vld) Bernashevka Beds (Vbrn) Bronnitsa Beds (Vbr)Zincov Beds (Vzn) Dzhurzhevka Beds (Vdz) Kalyus Beds
(Vkl) Pilipy Beds (Vpl) and Shebutintsy Beds (Vsb) Allthese local stratigraphic units are composed of terrigenousvarieties sandstones aleurolites mudstones tuffaceous claystone and greenstones (Table 2)
The majority of layers almost completely can be studiedeither in outcrops in northern part of the republic either inmapping drilling cores dug in areas covered by PaleozoicMesozoic and Cainozoic formations
In the region between Dniester and Prut Rivers Vendianlayers are laid-down directly in deposit on the surface ofcrystalline basement and the central region of Dniester Riverbasinmdashpartially on the Camenka diabases and Volyn Seriesmicroconglomerates
The lower limit of Vendian Formation in the Dniesterriver region has a dipping oriented to southwest (210ndash220∘)and dipping angle varies around the 401015840 (Figure 3) It shouldbe mentioned that the basement relief can be observed ingeomorphologic elements that are in direct connection withthe principal faults in the Dniester region The upper limitof Vendian Formation in the Podolian Tectonic Zone with asmall dipping to southndashsouth-western is disposed practicallyhorizontally and in the south-western of mentioned territoryin this chapter the lower limit is the same direction southndashsouth-western dipping with an angle about 201015840ndash301015840 By thissmall difference between the dipping angles of geological
Advances in Geology 9
Table2Ve
ndianageb
edsinthec
entralregion
oftheD
niesterR
iver
basin
Serie
sFo
rmations
Theb
eds(localstratigraph
icindices)
microfossilsv
arieties
(thickn
essinmeters)
Thea
verage
concentrations
ofΣRE
(La+
Ce+
Y)lowast
gt
dataarefrom
[7]
Kanilovka
Danilo
vka
Vdn
ShebutintsyB
eds(V
sb)mud
stonesa
ndbrow
nandredd
ish-brownaleurolites
with
sand
stone
intercalationsK
aniloviainsolatia
AJistVend
otaeniaantiq
uaGn
il(17ndash43
m)
54
Pilip
yBe
ds(V
pl)mud
stonesa
ndgreenish
gray
aleurolites
with
sand
stone
intercalations
Vend
otaeniaantiq
uaGn
il(18ndash38
m)
45
Mogilev-Po
dolsk
y
Nagoryany
Vng
Kalyu
sBeds(V
kl)dark
gray
with
brow
nnu
ance
mud
stonesph
osph
oriticc
oncretionscarbo
nate
inclu
sions
with
cone-in
-con
etextureV
endotaeniaantiq
uaGn
ilFu
sosqua
mulaAss
Pilitela
Ass
(55ndash80
m)
58
Dzhurzhevka
Beds
(Vdz)sand
stone
rhythm
icstratifi
catio
nsaleurolitesa
ndmud
stones
Nemiana
simplex
PalVend
otaeniaantiq
uaGn
il(10ndash
25m)
53
Jaryshev
Vjr
Zincov
Beds
(Vzn)mud
stonesrhythmicstratifi
catio
nswith
aleurolitessandstone
intercalations
(15ndash20
m)
60
Bron
nitsaB
eds(V
br)mud
stonesa
ndtuffaceou
sclaystonesgreenstonesw
ithmottledmud
stone
intercalationsB
ronicella
podolicaZa
ica-N
ov(20ndash25m
)64
Bernashe
vkaB
eds(V
brn)sandstonesw
ithmud
stone
intercalationsT
irasia
nadiscifarm
isPa
lEo
holin
iamasquensis
Gnill(5ndash20
m)
67
Mogilev
Vmg
Lyad
ovaB
eds(V
ld)mud
stonesa
ndgreensand
yaleurolitesgreensto
nesredd
ishtuffaceou
scla
ystonesin
theu
pper
levelsmdash
sand
stone
intercalationsLjadova
perjo
rata
Ass(20ndash
25m)
38
Cosau
tiBe
ds(V
ks)sand
stonesw
ithrare
gritstone
intercalations
andaleurolitesN
emiana
simplex
Pal(10ndash
18m)
65
Lomozov
Beds
(Vlm)mud
stonesw
ithaleurolites
andsand
stone
intercalations(0ndash
8m)
94Olcheda
yevB
eds(V
ol)theu
pper
levelsmdash
sand
stone
with
aleurolites
intercalationsthe
lower
levelsmdash
gritstone
with
desand
stone
insm
allsgrains
andmud
stone
intercalations(10ndash35m
)72
Volyn
Camenka
R()
Greenish
gray
aphyric
Diaba
sesw
itham
ygdaleform
impregnatio
nsof
plagiocla
se(1ndash
35m)
Soroca
Bedscon
glom
eratesm
icrocong
lomeratesarkoses
andstones(0ndash
10m)
AR-PR
1Cr
ystalline
basementrocksgneiss
escrystallin
eschistsplagiogranitesplagiomigmatites
enderbitesleucogranitesalaskites
lowast
Incompleted
atao
fspectrographica
nalysisthe
northern
partof
marketterritoryin
theF
igure1
10 Advances in Geology
limits is explained the slow increase of the thickness ofVendian Formation that in immediate nearness of Predo-brogean Depression exceeds 750ndash800 meters In contrastwith lower limit the surface of upper limit of Vendian wassubjected to relatively poor processes of denudation whichchanged the morphostructural aspect appeared after the endof sedimentogenesis processes
As a result of geochemical investigations it was estab-lished that in the lower layers of Vendian Formation theconcentration of RE elements compared with layers of upperlevels is relatively higher (Table 2) In particular it refers toOlchedayev Lomozov and Cosauti Beds of Mogilev Forma-tion For example in the southern part of the territory inOlchedayev Beds was detected an anomalous zone with quitehigh concentrations 119862La = 01 and 119862Ce = 008 [10] whichexceed the geochemical background that is approximately thesame as for Lanthanum and for Cerium
In terms of perspective of detecting some significantconcentrations of RE elements as a result of formationof mechanical aureoles consisting of zircon and mon-azite Olchedayev Lomozov and Cosauti beds represent anobject for much more detailed geological and geochemicalresearches
Olchedayev beds are composed by detrital sedimentaryrocks in big grains (varieties of conglomerates microcon-glomerates and sandstones) and mudstones or sandy mud-stones present in the layerrsquos body in form of relatively shallowintercalations
Geological section of Olchedayev beds is not stablethroughout the whole distribution area but in terms oflithological varieties which form layers and the complexstratifications of this local stratigraphic unit it is observed arelatively constant accordance in the lower levels are presentmicroconglomerates and in the upper onesmdashgritstone inbig grains Specific for Olchedayev layers is the presenceof a layer of clays and sandy clays which separate themicroconglomerates from gritstone
Geological section of Olchedayev beds constructed onbasis of mapping drillings in the southern part of the markedterritory in Figure 1 is presented in the following way
Directly on the altered surface of diabases of CamenkaFormation or on crystalline basement surface crust practi-cally devoid of erosion crust are laid-down
(1) Microconglomerates of brown color with angulargrains of quartz potash feldspar and diabases (up to20ndash25) the color is imposed by clayish cement richin iron hydroxides the thickness of this basal layervaries around 4 meters
(2) Rhythmic intercalations of arkose microconglomer-ates with sandstones in various grain of gray or gray-green color in both lithological varieties are presentinclusions of sandy clay stones and clay stones layerthicknessmdashabout 7 meters
(3) Dark gray microconglomerates with clastic grainsof quartz and potash feldspar microconglomeratecement is clayish and their thickness is 1 meter
(4) Greenish-brown and brown mudstones with thinintercalations of fines sandstone and sandy clay stonethickness 45 meters
(5) Gray and gray-reddish arkose gritstones with isolatedinclusions of quartz and potash feldspar (some grainsreach up to 5 millimeters in diameter) between thesandstones are found rare and thin intercalationsof dark gray mudstones thickness average about 7meters
(6) Gritstones of dark gray color with clayish cementthickness not exceeding 4 meters
(7) Quartz-feldspar gray and light gray sandstones indifferent grain including coarse grains are visiblehorizontal and oblique stratifications of differentgranular fractions sandstone thickness 50 meterson the quartz-feldspar sandstones are laid-down theLomozov Beds
The most common thickness of Olchedayev layers variesaround 25 meters
Sandstones and gritstones of Olchedayev Beds in theupper regions of geological section are of light gray colorIn lower areas depending on potash feldspar quantitiesthe color has reddish hues In microscopic sections areobserved sabulous silitic or mixed structures (sabulous-silitic) cement structure is silitic In terms of compositionthe rocks range from quartzose and arkose varieties Amountof feldspars (potash feldspar prevailed) in most cases doesnot exceed 50 by volume Both in the microconglomerates(also highlighted) and in the sandstones are frequent isolatedgrains of quartzite and rocks of crystalline basement In thelower levels of Olchedayev layers are found frequently smallscales of biotite
The degree of grains rounding from which are formedthe terrigenous rocks varieties of Olchedayev increases withtheir size coarse grains are round and smooth small grainsare ragged Often microconglomerates cement is amorphousmass clayish which together with rock grains imposedporosity quite evident
Accessory minerals in small quantities are presented bygarnet zircon and monazite A minus of geological researchcarried out in the mentioned region in this chapter consistedin that a mineralogical analysis which would determine thequantitative relations between zircon and monazite was notachieved As we have remarked the origin of mineralizationrich in RE elements in geological formations from the Dni-ester basin region is a great problem Additional informationwhich would facilitate the solving of this problem wouldpresent the thorough study of the separate grains of zirconandmonazite from the structure and composition andwouldbe extremely important in terms of geochronology It ispossible that the absolute ages of zircon and monazite shouldcoincide with the ages of these minerals found in crystallineformations of basement It did not exclude the case that theseminerals are different as assortment of isomorphic elementsin their chemical composition Such research are importantfor solving of various fundamental and practical geologicalproblems which can determine the origin of zircon and
Advances in Geology 11
monazite the sedimentogenes processes and the formationof mechanical aureoles with significant concentrations ofuseful components Unfortunately because of changes thathave intervened in the last decade of the past century in theRepublic of Moldova all expensive geological research wassuspended
In the Olchedayev rocks are found rare impregnationsof galena barite fluorite and xenotime (YPO
4) Because
monazite and zircon are contained isomorphic impurities ofTh and U and xenotimemdashabout 5 UO
2mdashOlchedayev Beds
are characterized by a relatively high radioactivity whichrarely reaches up to 500 and 780 micronshour
Lomozov beds are formed preponderant frommudstonesa dark gray color with mica they are intercalations ofsandstones finely dispersed The layers thickness has notbeen exceeding 5 meters In some places Lomozov rocks aremissing At level of Lomozov Beds is identified a complexlayer composed of very fine stratifications of fine-grainedsandstone and of dark gray mudstones relatively rich inminerals containingRE Because the average concentration ofLa + Ce + Y amount compared to other Vendian stratifica-tions is the largestmdash94 gt (Table 2)
The mudstones consisted of an amorphous mass ofgray color and in microscopic sections brown color withabundant additions of small scales of hydromica disposedparallel with surfaces of sedimentation On the fund of thisbasedmass are detected small granules (silitic) of quartz withangular forms In Lomozov Beds have a specific character inthe mudstones composition are often presented inclusions ofbiotite and more rarely of muscovite as elongated scales
Cosauti Beds in lithological point of view of this localstratigraphic unit are relatively homogeneous and are com-posed almost solely of sandstone Dark mudstone interca-lations and dispersed fine sandstone are marked only inpatches Cosauti sandstones have white color with sugaraspect in a homogeneous medium or small grain
In microscopic sections sandstones are psammitic clearstructure Aleurite fraction (01 millimeters) is about 5by rock volume (rarelymdash10ndash12) Large grains of quartzare frequent (about 2 millimeters) embedded in argillite-sandy mass (a few tenths of a percent) but in granulometricpoint of view sandstone are very well sorted In the Cosautibeds were discovered sandstone consist not only of quartzgrains Quartzose varieties usually contain about 10 ofdetrital material consisting of other minerals The quartz-feldspar and arkose sandstones are predominated in whichthe feldspar grains scant of above 20 (potassium feldsparis prevailing) It is common inclusions of biotite in the formof scales about 1-2 from volume Less commonly in therock small granules of quartzite are found In small isolatedgranules can be identified pyrite and magnetite Accessoryminerals are more frequent in zircon and monazite whichgenerated geochemical anomalies with relatively high con-centrations of REE
Cement of Cosauti sandstones is relatively variedchlorite-hydromicaceous (sometimes with added of kaolin ordikkite) silica or carbonated in which predominated calciteThe thickness of Cosauti Beds varies between 10 and 18meters
Compared with Olchedayev and Lomozov Beds variedby mineralogical and granulometric composition Vendiansection above Cosauti sandstones are relatively homogeneouson all distribution area A certain practical interest wouldpresent the mudstones of Kalyus Beds rich in phosphoriticconcretions
The morphostructure of Olchedayev Lomozov andCosauti beds succession (Vol + Vlm + Vks) in the Dniesterregion are presented quite homogeneous In terms oftectonic the main structural element within the mentionedterritory in this paper are presented by a segment of PodolianFaults Zone oriented in north-western direction and calledby autochthon geologists Dniester Fault (Figure 1) Effusionmagmatism with alkaline lava flows were distinguished thebeginning of a continental riftogenesis which was manifestedin later Proterozoic As a result of geological mapping ithas been shown that the basement along the Dniester Riverhas a narrow linear structure with typical features of riftvalley in which vertical dislocations amplitudes of basementblocks varies within 20ndash60m [2 3 7 10 18] Completed bythe Camenka diabase this structure in sedimentary coverlayers does not reflect practically anything This is observedby comparison of the crystalline basement relief shown inFigure 2 with the surface of lower limit of Vendian Formation(Figure 4) the latter being much smoother The crystallinebasement relief and the surface of lower limit of VendianFormation are observed linear zones oriented in transversaldirections Dniester Fault which occurred in result of thetectonic process much earliermdashin the south-west of pericra-tonic zone of the East European Platform late Archean wasformed a several tectonic faults oriented in preponderantlynorth-eastern direction [10] Perhaps along these faults hadoccurred more intensive erosion processes that had been ledto digging in the Archean relief negative linear forms
In the following way is explained the morphostructuralaspect of the succession beds which are at Vendian basedin the central region of the Dniester River basin Examiningthe summary thickness of Olchedayev Lomozov andCosautiBeds we see a series of relatively isometric areas whichhave comparatively larger thickness which is in correlationwith some earlier faults (Archean) in the region (Figure 4)Accordingly we conclude that the geological research indetection purpose of eventual essential accumulation of REelements should be continued in these areas with relativelylarger thickness of Vendian basal layers
5 Conclusion
(1) As a result of geological mapping in the basal layersof Moldavian Vendian at accessible depths for an eventualexploitation has been located REE mineralization At thesame time the prospect of these layers in the detection pointof view of some industrial accumulations of ores so far nothas been resolved Consequently in the opinion of manyexplorers studying of Vendian rocks needs to be continueduntil getting a univocal solution
(2) In terms of the geological formations of the centralregion of the Dniester river basin the minerals presenteda practical interest in terms of the formation of significant
12 Advances in Geology
0 10 20
(km)
The lower layers of platform cover
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of lower limit of the Vendian formation (m)
Distribution area of Camenka formation
minus160 minus120
minus140
minus80
minus80
minus60
minus40
0
20
30
30
30
40
40
40
40
40
40
40
40
40
50
50
50
50
50
50
50
60
60
60
60
60
80
Olchedayev-Vol Lomozov-Vlm Cosauti-Vks
Isopachites of lower Vendian layers (Vol + Vlm + Vks ) (m)
Figure 4 The lower layers of platform cover Olchedayev (Vol) Lomozov (Vlm) and Cosauti (Vks) Beds in the central region of the DniesterRiver basin [13]
accumulation of RE elements (Sc Y La Ce and Yb) aremonazite (phosphate) and zircon (silicate) probably zirconand monazite are paragenetically associated
(3) In order to locate in the underground space geo-chemical aureoles of the elements mentioned above it isnecessary to study carefully the conditions of migration andconcentration of these elements in diverse mineralogenesprocesses in conditions of the Dniester River basinmdashin theprogressive and retrograde metamorphism ultrametamor-phism metasomatic processes and training processes of thebasal layers of platform cover
(4) Based on the geological and geochemical data accu-mulated in the geological mapping to outline geochemicalaureoles and anomalies which may serve as a direct indexof the presence in crystalline and sedimentary formations ofmechanical aureoles of monazite and (or) zircon
(5) Geological research in detection purpose of eventualessential accumulation of RE elements in central region ofthe Dniester River basin should be continued in relativelylarger thickness of Vendian basal layers the OlchedayevLomozov and Cosauti Beds oriented along the Archean-Proterozoic tectonic faults
(6)The geochemical study of RE elements has remarkableimportance in interpretation and restoration of geological
processes of the geological past Because of this it is importantto investigate concentrations of these elements in differentvarieties of rocks of different ages and origins In particular itis important to establish particular paragenetic types betweenRE elements and other associated minerals to solve thegeological genetically problems
(i) to establish correlative links between particular typesof RE elements and particular types of crystalline orsedimentary rocks
(ii) to determine the origin of rocks which contain theseelements (formed in a single magmatic process in acommon metamorphic facies and in a single sedi-mentogenesis cycle)
If the detection of a deposit of zircon and monazite con-taining rare earths brings a direct practical result geochem-ical study of any region of the earth crust is of high particularimportance in geological prospection Because it solves agreat problem regarding the determination of parageneticassociations of minerals and chemical elements to determinethe type of petrographic provinces specifies geotectonicappearance of territories and to determine the links betweenlithogenic processes and palaeogeographic conditions in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Geological ResearchJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Geology Advances in
Advances in Geology 5
external zones Perhaps because of higher refractory prop-erties this accessory mineral passed from older geologicalformations in the younger ones without essential changesthat are imposed by anatexis and palingenetic processesProbably it also refers to monazite present in the samevarieties of rocks It produces the impression that multipleacts of progressive metamorphism ultrametamorphism andretrograde metamorphism that took place during an enor-mous period of geological time and modified in a cardinalway all petrologic varieties of the platform basement anddid not influence the redistribution in underground spaceof zircon and monazite The above-presented affirmationis supported by geochronological research data achievedthrough the radiological methods by Ukrainian geologists Inthe regions of Ukrainian Crystalline Shield slopemdashadjacentarea of Dniester River basin monazite and zircon in rockcomposition from formations mentioned above practicallyhave one and the same Archean age [11]
Many authors link the formation of concentrations ofRE elements in the Dniester region with the presence ofaccessory monazite and zircon which are present in compo-sition of different petrologic and lithological varieties of lateArchean early Proterozoic and Vendian ages [5] Remarkingthe high correlation coefficient between zircon and monazite(120588 = 073) and satisfactory degree of correlation (120578 =86 gt 3) we can assume that these two minerals interms of geology are syngenetic and probably as accessoryminerals were formed at the same time in one and the samepetrological formation At the same time we would liketo emphasize that monazite in the complex composition ofmetamorphic rocks of early Archaic age practically was notfound On the basis of the data from previous mineralogicaland geochemical researches it was determined that monaziteweight in geochemical aureoles formation (RE-elements) ismuch higher than that of zircon [12] We would like to notethat between crystalline and terrigenous formations in thisarea in quite small quantities can also be found othermineralscontaining rare earths (xenotime and allanite) [10]
Most of rare earth minerals including zircon and mon-azite are constituents of granite and nepheline-syenite peg-matites There are known endogenous deposits of the rareearths which are in geological-genetic relations with alkalinegranites intrusive alkaline ultrabasic rocks syenites (rich inpyrochlore) and pneumatolytic hydrothermal formations Ifwe examine the mineralogical compositions of the meta-morphic and ultrametamorphic rocks varieties in the centralregion of the Dniester River basin we will observe that inthese types of crystalline rocks in no way can form parage-netic associations with minerals which contain rare earths[9] It is possible that accessory mineralization of zircon andmonazite has no directly bearing to the origin of formationsfrom this area but can be part of some blocks of the earthrsquoscrust from neighboring regions For example in differentregions of the Ukrainian Crystalline Shield (Jitomir Vinita)in alkaline granitic and pegmatite rocks with monazite andzircon were found significant concentrations of RE elements(Lanthanum Cerium and Neodymium) [13]
From the above-said results that the issue of mineralsrsquoorigin (especially of zircon andmonazite) which contain rare
earths found in different varieties of crystalline rocks in thesouth-western East European Platform remains open
In terms of fundamental geotectonic concepts the oldestparts of the continental earth crustmdashcrystalline shieldsmdashduring the geologic time underwent several cardinal tectonicmodifications [14] Therefore it is presumed that in thetectonic cycle of theWhite Sea (Archean) the manifestationswhich are well observed in the Baltic Crystalline Shieldformations ended with intensive folding metamorphosingand profound granitization phenomena For correspondinggeological epoch is characteristic the formation of somegranite-gneiss domes delimited in the initial phase by linearzones consisting of volcanogenic-sedimentary rocks Atpresent these linear areas are transformed into relatively nar-row synclinorium formed of profoundly modified rocks indifferent metamorphic facies As a result of the epi-Archeantectonic processes (until early Proterozoic) we can assumethat in such synclinorium took place several epeirogenicmovements of crystalline basement concomitantly accom-panied by various destructive processes Consequently incertain places emerged aulacogens delimited by lineamentswithin which are found many remains of Archean blocksand areas with well-pronounced progressive and retrogrademetamorphism manifestations A similar structure could bethe Dniester Fault which de facto represents a segmentof Podolian Tectonic Faults Zone [15] and which delimitsin the south-western part another crystalline shield of EastEuropean PlatformmdashUkrainian Crystalline Shield Tectonicphenomena of early Proterozoic period ended with theconsolidation of the crystalline basement from region Insubsequent geological periods the tectonic activity graduallyreduced tominimum introducing in theDniester-Prut inter-fluves region only some structural changes genetically linkedto the evolution of Dniester Fault For example in Ripheanaround 950 million years along the Podolian Tectonic FaultsZone in a relatively weak process of continental riftogenesisoccurred alkaline lava flows in the result of which lenticularbodies of diabases were formed
Manifestations of effusive or intrusive magmatism inArchean-early Proterozoic in the central region of the Dni-ester River basin have not been determined It is possible thatultrametamorphic processes that took place in this regionin late Archean-early Proterozoic probably ldquoretouchedrdquo com-pletely initial igneous rocks in the area Consequently we cansay that zircon and monazite in the initial stages of geologic-structural formation of pericratonic region of south-westernpart of East European Platformwere already formed and werepart of the composition of pre-rocks
As mentioned above most endogenous deposits of REare genetically related either with alkaline granites intrusionsor alkaline typical intrusions Examining the contribution ofmagmatism in the evolution of earth crust it is determinedthat the alkaline magmatism events began about 25ndash27billion years ago and in an intensive way developed inPhanerozoic and arrived to maximal action in the MesozoicIn general alkaline rocks older than 27 billion years in theearth crust formations have not been found [16]Thus it maybe deduced that the origin of zircon and monazite detectedin geological formations in Dniester region in no way can be
6 Advances in Geology
linked with alkaline intrusions which may have been formedin the Ukrainian Crystalline Shield
It is obvious that theseminerals were formed however in amagmatic process unexplained so far by geologists interestedin the rare earths in the area and the issue of RE origin incomposition of metamorphic and ultrametamorphic rocksof the crystalline basement in the south-western part ofEast European Platform requires a serious investigation to besolved
There exist industrial concentrations of REminerals bothof endogenous type and metamorfogenic one Rare earthdeposits related tometamorphic formations are characterizedby relatively homogeneous distribution of RE elements onareas of significant extension and are presented in generallyby migmatites gneiss and metamorphosed conglomerateswith monazite of other origin It is not excluded that inthe geological formations of the crystalline basement arepresent accumulations of monazite (and zircon) located inplagiomigmatites and leucogranites which have a rather largedistribution in the Dniester region
4 Sedimentary Formations andDetection Premises of Concentrations ofRare Earths Elements
41 The Types of Hypergen Deposits of Rare Earths ElementsRare earths minerals of exogenous origin until now are notknown At the same time most rare earth deposits exploitedat present are of exogenous type
According to systematization of useful mineral depositstypes [17] hypergen deposits of RE are grouped into threetypes
(1) residual which are formed as a result of alterationof granite syenite nepheline-syenite rocks rich inmonazite sphene pyrochlore thorianite cerianiteand formation in erosion crust of a zone rich with REof cerium subgroup Nb Zr Th and Y
(2) sedimentary-detrital (a) alluvial lands formed fromconcentrations of stable minerals in hypergen zonesuch as monazite ilmenorutile zircon uranothorite(b) eluvium-adobe lands with high concentrationsof xenotime pyrochlore fergusonite thorite and (c)mineral lands of coastal areas consisting of significantaccumulations of monazite ilmenite rutile and zir-con
(3) sedimentary and sedimentary-biogenic (a) phospho-rites (b) sands rich in REminerals (c) shales and (d)fossil reminiscences
Referring to the territory in northern and north-eastern partof Republic of Moldova in the basal layers of sedimentarycover may be present the RE deposits such as detritalsediments This confirms the results of recent geological-geochemical researches carried out in the last decades of thelast century [7 18]
In hypergen areamonazite is a quite stable mineral Beingresistant to the action of exogenous agents it is not broken
down and in the following way in rubbly grains is keptvery long periods of geological timeTherefore the monazitepresent in crystalline rocks of Archean and early Proterozoicage is also found in sedimentary rocks of platform cover in thecentral region of the Dniester River basin Since the specificweight of monazite is quite high (exceeding 50 gcm3) inthe erosion process of rocks with accessory monazite andfurther sedimentogenesis of disintegrated material often areformed mechanical aureoles of this mineral Therefore it isexplained that the monazite in detrital sedimentary layersmay be present in concentrations much higher than itsconcentrations in the syngenetic rocks
For example in a drilling for geological mapping dugin the south of the marked territory in Figure 1 has beendetected a geochemical anomaly with maximum concentra-tions of lanthanum (01) and cerium (008) generated bymonazite the concentration of which in basal layers of thesedimentary cover varies between 05 and 218 gt [10]
In a similar process are also formed the mechanicalaureoles of zircon
Sedimentary cover in central region of the DniesterRiver basin is made up of several complex beds placedalmost horizontally In terms of geochronology of lithologicalcomposition of sedimentation conditions and diageneticprocesses in slope cover of southwestern part of theEast Euro-pean Platform are identified four formations and sedimentaryrock complexes Vendian Formation Ordovician-Silurianstratigraphic Complex Cretaceous Formation and NeogeneFormation (note currently in many countries the name ofstratigraphic unit Vendian is replaced with Ediacaran butin Republic of Moldova so far remain the same names ofstratigraphic units used in Russia)
Ordovician-Silurian beds consisting prevailingly oflimestone-dolomite varieties limestone-siliceous rocks ofCretaceous and diversity of limestone sand and clay varietiesof Neogene age in terms of the problem approached in thischapter unlike the Vendian basal layers of sedimentarycover do not present any practical interest
By direct comparison it was demonstrated that thegeological section of Podolian Vendian is stratotype almostfor all formations of this age opened in different regionsof the East European Platform Thus Vendian age layerssituated in natural cropping or crossed by drilling in the northand north-eastern zone of Republic of Moldova presenta southeastern fragment of Podolian Vendian and in anatural way without assumptions the stratigraphic scheme ofUkrainian geologists can also be applied in the Dniester riverbasin conditions For a rather complete documentation aboutVendian Formation in the region we make reference to aquite ample synthesis work prepared by Ukrainian geologistsforTheThird International Symposium on Cambrian System(Kiev 1990) [19]
42 Camenka Formation Directly on the surface of crys-talline basement are laid-down in the deposit the layersof Camenka Formation constituted of basal conglomeratesand diabases probably of Riphean age The formation body(average thickness about 20 meters) has a lenticular-flat
Advances in Geology 7
The distribution area of Camenka formation
Central region of the Dniester River basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of crystalline basement surface (m)Isopachites of Camenka formation (m)
0 10 20
(km) minus280
minus240
minus160
20
40minus140minus260
minus200
minus180
minus160
minus80
minus80
60
minus60
minus200
minus100minus140 1
0
10
10
10
10
10
20
20
20
20
20
20
20
20
20
20
minus40
minus20
minus20
0
30
0
0
30
30
80
Figure 2 The distribution area of Camenka Formation in the central region of the Dniester River basin [13]
aspect is relatively narrow (8ndash10 kilometers in cross section)is oriented in a north-western direction and covers thelinear-depressive zone of Dniester Fault (Figure 2) We canassume that the centers of lenticular forms coincide withchannels throughwhich on the earth surface poured lavawithalkaline composition specific for early stages of continentalriftogenesisThe phenomenon took place in later Proterozoicin one of the last phases of tectonic activity in south-westernareas of the East European Platform
Camenka Formation consists of diabases and a basal layerof microconglomerates and conglomerates (Soroca Beds)
Lithological varieties of Soroca in the spread region ofFormation Camenka do not present an integral structuralunit Firstly these lithological varieties are in deposits just inthe spread zone of diabases and only in someplaces vulcanitesof Camenka Formation are laid-down directly in depositon the surface of crystalline basement Perhaps Sorocabasal beds in the mentioned region had had a much largespread but because of denudation processes were preservedonly under diabases Thickness of Soroca Beds crossed bydrilling mapping varies from 05 to 35 meters Rocks aredistinguished by their mineralogical composition and areformed from an unselected rubbly material conglomeratesconglomerate-breccias microconglomerates (predominant)coarse-grained sandstones and arkose sandstones (rarely)
The rubbly material is presented by slightly rounded grainsof crystalline basement rocksmdashquartzite potash feldsparand biotite scales cemented with a brown argilitic materialCement volume typically exceeds 50 by volume In thefollowing way most of Soroca Bedsrsquo rocks differ by theirspecific brown color
Arkose sandstones and microconglomerates that can befound in the composition of the basal layers of Camenka For-mation are massive rocks hard of gray-green or pink-graycolor have sabulous structures and consist of plagioclase (upto 50ndash60) potash feldspar (up to 15) quartz (25 to 35)cement and grains of basement rocks
In clastic material are prevalent semirounded or ruggedforms and grainsrsquo sizes range from 10ndash15 millimeters(microconglomerates) 10ndash01 millimeters (sandstones)01 millimeters (sandy mudstones) Cement has a highporosity and has a kaolin-hydromicaceous kaolin-chlorite-hydromicaceous or kaolin composition
From accessory minerals are present small grains ofgarnet zircon monazite apatite and titanomagnetite
The rocks of Soroca Beds have a specific radioactivity rel-atively high (30ndash35 micronshour) imposed by the presenceof isomorphic thorium in the monazite composition
Based on geochemical investigations of Sorocamicrocon-glomerate were found relatively high concentrations of La
8 Advances in Geology
0 10 20
(km)
The morfostructure of Vendian formation
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isopachites of Vendian layers (m)Isohypses of upper limit of the Vendian formation (m)
minus80
minus60
minus40
minus20
minus20
0
0
0
20
20
20
20
40
40
40
40
60
60
60
60
80
80
80
80
100
100
100
120
120
120
140
140
140
160
160
160
180
180
180
180
180
200
200
200
200
200
200
220
220
220
220
220
240
240
240
240
240
260
260
260
280
280
280300
Figure 3 The morphostructure of Vendian Formation in the central region of the Dniester River basin [13]
Diabases predominate in Camenka Formation and inaxial zone of the banded body exceed the thickness of 30ndash40m In macroscopic point of view diabases are compactvolcanogenic rocks of a dark gray gray-brown or darkgreenish color with a relatively high specific weight Theirstructure is cryptocrystalline or crystalline in very smallgrains Between diabases discovered in the Dniester areathere are two varietiesmdashaphyric diabase and diabase withan apparently porphyric texture Usually porphyric inclu-sions have various sizes (1ndash15 millimeters) and consist ofcalcite and rarely chlorite Most diabases have an ophyticstructure and massive texture and in their composition areincluded basic plagioclase (40ndash50) monoclinic pyroxene(5ndash19) chlorite (30ndash35) epidote (3ndash7) and titanomag-netite (5ndash10)Theminerals which contained RE elements inCamenka Formation were not detected
43 Terrigenous Layers from the Vendian Lower LevelAccording to the stratigraphic schemeused byMoldavian andUkrainian geologists [20] the formations of Vendian age aredifferentiated in series which include several beds In normalsequence Moldavian Vendian is composed of OlchedayevBeds (Vol) LomozovBeds (Vlm) Cosauti Beds (Vks) LyadovaBeds (Vld) Bernashevka Beds (Vbrn) Bronnitsa Beds (Vbr)Zincov Beds (Vzn) Dzhurzhevka Beds (Vdz) Kalyus Beds
(Vkl) Pilipy Beds (Vpl) and Shebutintsy Beds (Vsb) Allthese local stratigraphic units are composed of terrigenousvarieties sandstones aleurolites mudstones tuffaceous claystone and greenstones (Table 2)
The majority of layers almost completely can be studiedeither in outcrops in northern part of the republic either inmapping drilling cores dug in areas covered by PaleozoicMesozoic and Cainozoic formations
In the region between Dniester and Prut Rivers Vendianlayers are laid-down directly in deposit on the surface ofcrystalline basement and the central region of Dniester Riverbasinmdashpartially on the Camenka diabases and Volyn Seriesmicroconglomerates
The lower limit of Vendian Formation in the Dniesterriver region has a dipping oriented to southwest (210ndash220∘)and dipping angle varies around the 401015840 (Figure 3) It shouldbe mentioned that the basement relief can be observed ingeomorphologic elements that are in direct connection withthe principal faults in the Dniester region The upper limitof Vendian Formation in the Podolian Tectonic Zone with asmall dipping to southndashsouth-western is disposed practicallyhorizontally and in the south-western of mentioned territoryin this chapter the lower limit is the same direction southndashsouth-western dipping with an angle about 201015840ndash301015840 By thissmall difference between the dipping angles of geological
Advances in Geology 9
Table2Ve
ndianageb
edsinthec
entralregion
oftheD
niesterR
iver
basin
Serie
sFo
rmations
Theb
eds(localstratigraph
icindices)
microfossilsv
arieties
(thickn
essinmeters)
Thea
verage
concentrations
ofΣRE
(La+
Ce+
Y)lowast
gt
dataarefrom
[7]
Kanilovka
Danilo
vka
Vdn
ShebutintsyB
eds(V
sb)mud
stonesa
ndbrow
nandredd
ish-brownaleurolites
with
sand
stone
intercalationsK
aniloviainsolatia
AJistVend
otaeniaantiq
uaGn
il(17ndash43
m)
54
Pilip
yBe
ds(V
pl)mud
stonesa
ndgreenish
gray
aleurolites
with
sand
stone
intercalations
Vend
otaeniaantiq
uaGn
il(18ndash38
m)
45
Mogilev-Po
dolsk
y
Nagoryany
Vng
Kalyu
sBeds(V
kl)dark
gray
with
brow
nnu
ance
mud
stonesph
osph
oriticc
oncretionscarbo
nate
inclu
sions
with
cone-in
-con
etextureV
endotaeniaantiq
uaGn
ilFu
sosqua
mulaAss
Pilitela
Ass
(55ndash80
m)
58
Dzhurzhevka
Beds
(Vdz)sand
stone
rhythm
icstratifi
catio
nsaleurolitesa
ndmud
stones
Nemiana
simplex
PalVend
otaeniaantiq
uaGn
il(10ndash
25m)
53
Jaryshev
Vjr
Zincov
Beds
(Vzn)mud
stonesrhythmicstratifi
catio
nswith
aleurolitessandstone
intercalations
(15ndash20
m)
60
Bron
nitsaB
eds(V
br)mud
stonesa
ndtuffaceou
sclaystonesgreenstonesw
ithmottledmud
stone
intercalationsB
ronicella
podolicaZa
ica-N
ov(20ndash25m
)64
Bernashe
vkaB
eds(V
brn)sandstonesw
ithmud
stone
intercalationsT
irasia
nadiscifarm
isPa
lEo
holin
iamasquensis
Gnill(5ndash20
m)
67
Mogilev
Vmg
Lyad
ovaB
eds(V
ld)mud
stonesa
ndgreensand
yaleurolitesgreensto
nesredd
ishtuffaceou
scla
ystonesin
theu
pper
levelsmdash
sand
stone
intercalationsLjadova
perjo
rata
Ass(20ndash
25m)
38
Cosau
tiBe
ds(V
ks)sand
stonesw
ithrare
gritstone
intercalations
andaleurolitesN
emiana
simplex
Pal(10ndash
18m)
65
Lomozov
Beds
(Vlm)mud
stonesw
ithaleurolites
andsand
stone
intercalations(0ndash
8m)
94Olcheda
yevB
eds(V
ol)theu
pper
levelsmdash
sand
stone
with
aleurolites
intercalationsthe
lower
levelsmdash
gritstone
with
desand
stone
insm
allsgrains
andmud
stone
intercalations(10ndash35m
)72
Volyn
Camenka
R()
Greenish
gray
aphyric
Diaba
sesw
itham
ygdaleform
impregnatio
nsof
plagiocla
se(1ndash
35m)
Soroca
Bedscon
glom
eratesm
icrocong
lomeratesarkoses
andstones(0ndash
10m)
AR-PR
1Cr
ystalline
basementrocksgneiss
escrystallin
eschistsplagiogranitesplagiomigmatites
enderbitesleucogranitesalaskites
lowast
Incompleted
atao
fspectrographica
nalysisthe
northern
partof
marketterritoryin
theF
igure1
10 Advances in Geology
limits is explained the slow increase of the thickness ofVendian Formation that in immediate nearness of Predo-brogean Depression exceeds 750ndash800 meters In contrastwith lower limit the surface of upper limit of Vendian wassubjected to relatively poor processes of denudation whichchanged the morphostructural aspect appeared after the endof sedimentogenesis processes
As a result of geochemical investigations it was estab-lished that in the lower layers of Vendian Formation theconcentration of RE elements compared with layers of upperlevels is relatively higher (Table 2) In particular it refers toOlchedayev Lomozov and Cosauti Beds of Mogilev Forma-tion For example in the southern part of the territory inOlchedayev Beds was detected an anomalous zone with quitehigh concentrations 119862La = 01 and 119862Ce = 008 [10] whichexceed the geochemical background that is approximately thesame as for Lanthanum and for Cerium
In terms of perspective of detecting some significantconcentrations of RE elements as a result of formationof mechanical aureoles consisting of zircon and mon-azite Olchedayev Lomozov and Cosauti beds represent anobject for much more detailed geological and geochemicalresearches
Olchedayev beds are composed by detrital sedimentaryrocks in big grains (varieties of conglomerates microcon-glomerates and sandstones) and mudstones or sandy mud-stones present in the layerrsquos body in form of relatively shallowintercalations
Geological section of Olchedayev beds is not stablethroughout the whole distribution area but in terms oflithological varieties which form layers and the complexstratifications of this local stratigraphic unit it is observed arelatively constant accordance in the lower levels are presentmicroconglomerates and in the upper onesmdashgritstone inbig grains Specific for Olchedayev layers is the presenceof a layer of clays and sandy clays which separate themicroconglomerates from gritstone
Geological section of Olchedayev beds constructed onbasis of mapping drillings in the southern part of the markedterritory in Figure 1 is presented in the following way
Directly on the altered surface of diabases of CamenkaFormation or on crystalline basement surface crust practi-cally devoid of erosion crust are laid-down
(1) Microconglomerates of brown color with angulargrains of quartz potash feldspar and diabases (up to20ndash25) the color is imposed by clayish cement richin iron hydroxides the thickness of this basal layervaries around 4 meters
(2) Rhythmic intercalations of arkose microconglomer-ates with sandstones in various grain of gray or gray-green color in both lithological varieties are presentinclusions of sandy clay stones and clay stones layerthicknessmdashabout 7 meters
(3) Dark gray microconglomerates with clastic grainsof quartz and potash feldspar microconglomeratecement is clayish and their thickness is 1 meter
(4) Greenish-brown and brown mudstones with thinintercalations of fines sandstone and sandy clay stonethickness 45 meters
(5) Gray and gray-reddish arkose gritstones with isolatedinclusions of quartz and potash feldspar (some grainsreach up to 5 millimeters in diameter) between thesandstones are found rare and thin intercalationsof dark gray mudstones thickness average about 7meters
(6) Gritstones of dark gray color with clayish cementthickness not exceeding 4 meters
(7) Quartz-feldspar gray and light gray sandstones indifferent grain including coarse grains are visiblehorizontal and oblique stratifications of differentgranular fractions sandstone thickness 50 meterson the quartz-feldspar sandstones are laid-down theLomozov Beds
The most common thickness of Olchedayev layers variesaround 25 meters
Sandstones and gritstones of Olchedayev Beds in theupper regions of geological section are of light gray colorIn lower areas depending on potash feldspar quantitiesthe color has reddish hues In microscopic sections areobserved sabulous silitic or mixed structures (sabulous-silitic) cement structure is silitic In terms of compositionthe rocks range from quartzose and arkose varieties Amountof feldspars (potash feldspar prevailed) in most cases doesnot exceed 50 by volume Both in the microconglomerates(also highlighted) and in the sandstones are frequent isolatedgrains of quartzite and rocks of crystalline basement In thelower levels of Olchedayev layers are found frequently smallscales of biotite
The degree of grains rounding from which are formedthe terrigenous rocks varieties of Olchedayev increases withtheir size coarse grains are round and smooth small grainsare ragged Often microconglomerates cement is amorphousmass clayish which together with rock grains imposedporosity quite evident
Accessory minerals in small quantities are presented bygarnet zircon and monazite A minus of geological researchcarried out in the mentioned region in this chapter consistedin that a mineralogical analysis which would determine thequantitative relations between zircon and monazite was notachieved As we have remarked the origin of mineralizationrich in RE elements in geological formations from the Dni-ester basin region is a great problem Additional informationwhich would facilitate the solving of this problem wouldpresent the thorough study of the separate grains of zirconandmonazite from the structure and composition andwouldbe extremely important in terms of geochronology It ispossible that the absolute ages of zircon and monazite shouldcoincide with the ages of these minerals found in crystallineformations of basement It did not exclude the case that theseminerals are different as assortment of isomorphic elementsin their chemical composition Such research are importantfor solving of various fundamental and practical geologicalproblems which can determine the origin of zircon and
Advances in Geology 11
monazite the sedimentogenes processes and the formationof mechanical aureoles with significant concentrations ofuseful components Unfortunately because of changes thathave intervened in the last decade of the past century in theRepublic of Moldova all expensive geological research wassuspended
In the Olchedayev rocks are found rare impregnationsof galena barite fluorite and xenotime (YPO
4) Because
monazite and zircon are contained isomorphic impurities ofTh and U and xenotimemdashabout 5 UO
2mdashOlchedayev Beds
are characterized by a relatively high radioactivity whichrarely reaches up to 500 and 780 micronshour
Lomozov beds are formed preponderant frommudstonesa dark gray color with mica they are intercalations ofsandstones finely dispersed The layers thickness has notbeen exceeding 5 meters In some places Lomozov rocks aremissing At level of Lomozov Beds is identified a complexlayer composed of very fine stratifications of fine-grainedsandstone and of dark gray mudstones relatively rich inminerals containingRE Because the average concentration ofLa + Ce + Y amount compared to other Vendian stratifica-tions is the largestmdash94 gt (Table 2)
The mudstones consisted of an amorphous mass ofgray color and in microscopic sections brown color withabundant additions of small scales of hydromica disposedparallel with surfaces of sedimentation On the fund of thisbasedmass are detected small granules (silitic) of quartz withangular forms In Lomozov Beds have a specific character inthe mudstones composition are often presented inclusions ofbiotite and more rarely of muscovite as elongated scales
Cosauti Beds in lithological point of view of this localstratigraphic unit are relatively homogeneous and are com-posed almost solely of sandstone Dark mudstone interca-lations and dispersed fine sandstone are marked only inpatches Cosauti sandstones have white color with sugaraspect in a homogeneous medium or small grain
In microscopic sections sandstones are psammitic clearstructure Aleurite fraction (01 millimeters) is about 5by rock volume (rarelymdash10ndash12) Large grains of quartzare frequent (about 2 millimeters) embedded in argillite-sandy mass (a few tenths of a percent) but in granulometricpoint of view sandstone are very well sorted In the Cosautibeds were discovered sandstone consist not only of quartzgrains Quartzose varieties usually contain about 10 ofdetrital material consisting of other minerals The quartz-feldspar and arkose sandstones are predominated in whichthe feldspar grains scant of above 20 (potassium feldsparis prevailing) It is common inclusions of biotite in the formof scales about 1-2 from volume Less commonly in therock small granules of quartzite are found In small isolatedgranules can be identified pyrite and magnetite Accessoryminerals are more frequent in zircon and monazite whichgenerated geochemical anomalies with relatively high con-centrations of REE
Cement of Cosauti sandstones is relatively variedchlorite-hydromicaceous (sometimes with added of kaolin ordikkite) silica or carbonated in which predominated calciteThe thickness of Cosauti Beds varies between 10 and 18meters
Compared with Olchedayev and Lomozov Beds variedby mineralogical and granulometric composition Vendiansection above Cosauti sandstones are relatively homogeneouson all distribution area A certain practical interest wouldpresent the mudstones of Kalyus Beds rich in phosphoriticconcretions
The morphostructure of Olchedayev Lomozov andCosauti beds succession (Vol + Vlm + Vks) in the Dniesterregion are presented quite homogeneous In terms oftectonic the main structural element within the mentionedterritory in this paper are presented by a segment of PodolianFaults Zone oriented in north-western direction and calledby autochthon geologists Dniester Fault (Figure 1) Effusionmagmatism with alkaline lava flows were distinguished thebeginning of a continental riftogenesis which was manifestedin later Proterozoic As a result of geological mapping ithas been shown that the basement along the Dniester Riverhas a narrow linear structure with typical features of riftvalley in which vertical dislocations amplitudes of basementblocks varies within 20ndash60m [2 3 7 10 18] Completed bythe Camenka diabase this structure in sedimentary coverlayers does not reflect practically anything This is observedby comparison of the crystalline basement relief shown inFigure 2 with the surface of lower limit of Vendian Formation(Figure 4) the latter being much smoother The crystallinebasement relief and the surface of lower limit of VendianFormation are observed linear zones oriented in transversaldirections Dniester Fault which occurred in result of thetectonic process much earliermdashin the south-west of pericra-tonic zone of the East European Platform late Archean wasformed a several tectonic faults oriented in preponderantlynorth-eastern direction [10] Perhaps along these faults hadoccurred more intensive erosion processes that had been ledto digging in the Archean relief negative linear forms
In the following way is explained the morphostructuralaspect of the succession beds which are at Vendian basedin the central region of the Dniester River basin Examiningthe summary thickness of Olchedayev Lomozov andCosautiBeds we see a series of relatively isometric areas whichhave comparatively larger thickness which is in correlationwith some earlier faults (Archean) in the region (Figure 4)Accordingly we conclude that the geological research indetection purpose of eventual essential accumulation of REelements should be continued in these areas with relativelylarger thickness of Vendian basal layers
5 Conclusion
(1) As a result of geological mapping in the basal layersof Moldavian Vendian at accessible depths for an eventualexploitation has been located REE mineralization At thesame time the prospect of these layers in the detection pointof view of some industrial accumulations of ores so far nothas been resolved Consequently in the opinion of manyexplorers studying of Vendian rocks needs to be continueduntil getting a univocal solution
(2) In terms of the geological formations of the centralregion of the Dniester river basin the minerals presenteda practical interest in terms of the formation of significant
12 Advances in Geology
0 10 20
(km)
The lower layers of platform cover
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of lower limit of the Vendian formation (m)
Distribution area of Camenka formation
minus160 minus120
minus140
minus80
minus80
minus60
minus40
0
20
30
30
30
40
40
40
40
40
40
40
40
40
50
50
50
50
50
50
50
60
60
60
60
60
80
Olchedayev-Vol Lomozov-Vlm Cosauti-Vks
Isopachites of lower Vendian layers (Vol + Vlm + Vks ) (m)
Figure 4 The lower layers of platform cover Olchedayev (Vol) Lomozov (Vlm) and Cosauti (Vks) Beds in the central region of the DniesterRiver basin [13]
accumulation of RE elements (Sc Y La Ce and Yb) aremonazite (phosphate) and zircon (silicate) probably zirconand monazite are paragenetically associated
(3) In order to locate in the underground space geo-chemical aureoles of the elements mentioned above it isnecessary to study carefully the conditions of migration andconcentration of these elements in diverse mineralogenesprocesses in conditions of the Dniester River basinmdashin theprogressive and retrograde metamorphism ultrametamor-phism metasomatic processes and training processes of thebasal layers of platform cover
(4) Based on the geological and geochemical data accu-mulated in the geological mapping to outline geochemicalaureoles and anomalies which may serve as a direct indexof the presence in crystalline and sedimentary formations ofmechanical aureoles of monazite and (or) zircon
(5) Geological research in detection purpose of eventualessential accumulation of RE elements in central region ofthe Dniester River basin should be continued in relativelylarger thickness of Vendian basal layers the OlchedayevLomozov and Cosauti Beds oriented along the Archean-Proterozoic tectonic faults
(6)The geochemical study of RE elements has remarkableimportance in interpretation and restoration of geological
processes of the geological past Because of this it is importantto investigate concentrations of these elements in differentvarieties of rocks of different ages and origins In particular itis important to establish particular paragenetic types betweenRE elements and other associated minerals to solve thegeological genetically problems
(i) to establish correlative links between particular typesof RE elements and particular types of crystalline orsedimentary rocks
(ii) to determine the origin of rocks which contain theseelements (formed in a single magmatic process in acommon metamorphic facies and in a single sedi-mentogenesis cycle)
If the detection of a deposit of zircon and monazite con-taining rare earths brings a direct practical result geochem-ical study of any region of the earth crust is of high particularimportance in geological prospection Because it solves agreat problem regarding the determination of parageneticassociations of minerals and chemical elements to determinethe type of petrographic provinces specifies geotectonicappearance of territories and to determine the links betweenlithogenic processes and palaeogeographic conditions in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Mining
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GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Geology Advances in
6 Advances in Geology
linked with alkaline intrusions which may have been formedin the Ukrainian Crystalline Shield
It is obvious that theseminerals were formed however in amagmatic process unexplained so far by geologists interestedin the rare earths in the area and the issue of RE origin incomposition of metamorphic and ultrametamorphic rocksof the crystalline basement in the south-western part ofEast European Platform requires a serious investigation to besolved
There exist industrial concentrations of REminerals bothof endogenous type and metamorfogenic one Rare earthdeposits related tometamorphic formations are characterizedby relatively homogeneous distribution of RE elements onareas of significant extension and are presented in generallyby migmatites gneiss and metamorphosed conglomerateswith monazite of other origin It is not excluded that inthe geological formations of the crystalline basement arepresent accumulations of monazite (and zircon) located inplagiomigmatites and leucogranites which have a rather largedistribution in the Dniester region
4 Sedimentary Formations andDetection Premises of Concentrations ofRare Earths Elements
41 The Types of Hypergen Deposits of Rare Earths ElementsRare earths minerals of exogenous origin until now are notknown At the same time most rare earth deposits exploitedat present are of exogenous type
According to systematization of useful mineral depositstypes [17] hypergen deposits of RE are grouped into threetypes
(1) residual which are formed as a result of alterationof granite syenite nepheline-syenite rocks rich inmonazite sphene pyrochlore thorianite cerianiteand formation in erosion crust of a zone rich with REof cerium subgroup Nb Zr Th and Y
(2) sedimentary-detrital (a) alluvial lands formed fromconcentrations of stable minerals in hypergen zonesuch as monazite ilmenorutile zircon uranothorite(b) eluvium-adobe lands with high concentrationsof xenotime pyrochlore fergusonite thorite and (c)mineral lands of coastal areas consisting of significantaccumulations of monazite ilmenite rutile and zir-con
(3) sedimentary and sedimentary-biogenic (a) phospho-rites (b) sands rich in REminerals (c) shales and (d)fossil reminiscences
Referring to the territory in northern and north-eastern partof Republic of Moldova in the basal layers of sedimentarycover may be present the RE deposits such as detritalsediments This confirms the results of recent geological-geochemical researches carried out in the last decades of thelast century [7 18]
In hypergen areamonazite is a quite stable mineral Beingresistant to the action of exogenous agents it is not broken
down and in the following way in rubbly grains is keptvery long periods of geological timeTherefore the monazitepresent in crystalline rocks of Archean and early Proterozoicage is also found in sedimentary rocks of platform cover in thecentral region of the Dniester River basin Since the specificweight of monazite is quite high (exceeding 50 gcm3) inthe erosion process of rocks with accessory monazite andfurther sedimentogenesis of disintegrated material often areformed mechanical aureoles of this mineral Therefore it isexplained that the monazite in detrital sedimentary layersmay be present in concentrations much higher than itsconcentrations in the syngenetic rocks
For example in a drilling for geological mapping dugin the south of the marked territory in Figure 1 has beendetected a geochemical anomaly with maximum concentra-tions of lanthanum (01) and cerium (008) generated bymonazite the concentration of which in basal layers of thesedimentary cover varies between 05 and 218 gt [10]
In a similar process are also formed the mechanicalaureoles of zircon
Sedimentary cover in central region of the DniesterRiver basin is made up of several complex beds placedalmost horizontally In terms of geochronology of lithologicalcomposition of sedimentation conditions and diageneticprocesses in slope cover of southwestern part of theEast Euro-pean Platform are identified four formations and sedimentaryrock complexes Vendian Formation Ordovician-Silurianstratigraphic Complex Cretaceous Formation and NeogeneFormation (note currently in many countries the name ofstratigraphic unit Vendian is replaced with Ediacaran butin Republic of Moldova so far remain the same names ofstratigraphic units used in Russia)
Ordovician-Silurian beds consisting prevailingly oflimestone-dolomite varieties limestone-siliceous rocks ofCretaceous and diversity of limestone sand and clay varietiesof Neogene age in terms of the problem approached in thischapter unlike the Vendian basal layers of sedimentarycover do not present any practical interest
By direct comparison it was demonstrated that thegeological section of Podolian Vendian is stratotype almostfor all formations of this age opened in different regionsof the East European Platform Thus Vendian age layerssituated in natural cropping or crossed by drilling in the northand north-eastern zone of Republic of Moldova presenta southeastern fragment of Podolian Vendian and in anatural way without assumptions the stratigraphic scheme ofUkrainian geologists can also be applied in the Dniester riverbasin conditions For a rather complete documentation aboutVendian Formation in the region we make reference to aquite ample synthesis work prepared by Ukrainian geologistsforTheThird International Symposium on Cambrian System(Kiev 1990) [19]
42 Camenka Formation Directly on the surface of crys-talline basement are laid-down in the deposit the layersof Camenka Formation constituted of basal conglomeratesand diabases probably of Riphean age The formation body(average thickness about 20 meters) has a lenticular-flat
Advances in Geology 7
The distribution area of Camenka formation
Central region of the Dniester River basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of crystalline basement surface (m)Isopachites of Camenka formation (m)
0 10 20
(km) minus280
minus240
minus160
20
40minus140minus260
minus200
minus180
minus160
minus80
minus80
60
minus60
minus200
minus100minus140 1
0
10
10
10
10
10
20
20
20
20
20
20
20
20
20
20
minus40
minus20
minus20
0
30
0
0
30
30
80
Figure 2 The distribution area of Camenka Formation in the central region of the Dniester River basin [13]
aspect is relatively narrow (8ndash10 kilometers in cross section)is oriented in a north-western direction and covers thelinear-depressive zone of Dniester Fault (Figure 2) We canassume that the centers of lenticular forms coincide withchannels throughwhich on the earth surface poured lavawithalkaline composition specific for early stages of continentalriftogenesisThe phenomenon took place in later Proterozoicin one of the last phases of tectonic activity in south-westernareas of the East European Platform
Camenka Formation consists of diabases and a basal layerof microconglomerates and conglomerates (Soroca Beds)
Lithological varieties of Soroca in the spread region ofFormation Camenka do not present an integral structuralunit Firstly these lithological varieties are in deposits just inthe spread zone of diabases and only in someplaces vulcanitesof Camenka Formation are laid-down directly in depositon the surface of crystalline basement Perhaps Sorocabasal beds in the mentioned region had had a much largespread but because of denudation processes were preservedonly under diabases Thickness of Soroca Beds crossed bydrilling mapping varies from 05 to 35 meters Rocks aredistinguished by their mineralogical composition and areformed from an unselected rubbly material conglomeratesconglomerate-breccias microconglomerates (predominant)coarse-grained sandstones and arkose sandstones (rarely)
The rubbly material is presented by slightly rounded grainsof crystalline basement rocksmdashquartzite potash feldsparand biotite scales cemented with a brown argilitic materialCement volume typically exceeds 50 by volume In thefollowing way most of Soroca Bedsrsquo rocks differ by theirspecific brown color
Arkose sandstones and microconglomerates that can befound in the composition of the basal layers of Camenka For-mation are massive rocks hard of gray-green or pink-graycolor have sabulous structures and consist of plagioclase (upto 50ndash60) potash feldspar (up to 15) quartz (25 to 35)cement and grains of basement rocks
In clastic material are prevalent semirounded or ruggedforms and grainsrsquo sizes range from 10ndash15 millimeters(microconglomerates) 10ndash01 millimeters (sandstones)01 millimeters (sandy mudstones) Cement has a highporosity and has a kaolin-hydromicaceous kaolin-chlorite-hydromicaceous or kaolin composition
From accessory minerals are present small grains ofgarnet zircon monazite apatite and titanomagnetite
The rocks of Soroca Beds have a specific radioactivity rel-atively high (30ndash35 micronshour) imposed by the presenceof isomorphic thorium in the monazite composition
Based on geochemical investigations of Sorocamicrocon-glomerate were found relatively high concentrations of La
8 Advances in Geology
0 10 20
(km)
The morfostructure of Vendian formation
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isopachites of Vendian layers (m)Isohypses of upper limit of the Vendian formation (m)
minus80
minus60
minus40
minus20
minus20
0
0
0
20
20
20
20
40
40
40
40
60
60
60
60
80
80
80
80
100
100
100
120
120
120
140
140
140
160
160
160
180
180
180
180
180
200
200
200
200
200
200
220
220
220
220
220
240
240
240
240
240
260
260
260
280
280
280300
Figure 3 The morphostructure of Vendian Formation in the central region of the Dniester River basin [13]
Diabases predominate in Camenka Formation and inaxial zone of the banded body exceed the thickness of 30ndash40m In macroscopic point of view diabases are compactvolcanogenic rocks of a dark gray gray-brown or darkgreenish color with a relatively high specific weight Theirstructure is cryptocrystalline or crystalline in very smallgrains Between diabases discovered in the Dniester areathere are two varietiesmdashaphyric diabase and diabase withan apparently porphyric texture Usually porphyric inclu-sions have various sizes (1ndash15 millimeters) and consist ofcalcite and rarely chlorite Most diabases have an ophyticstructure and massive texture and in their composition areincluded basic plagioclase (40ndash50) monoclinic pyroxene(5ndash19) chlorite (30ndash35) epidote (3ndash7) and titanomag-netite (5ndash10)Theminerals which contained RE elements inCamenka Formation were not detected
43 Terrigenous Layers from the Vendian Lower LevelAccording to the stratigraphic schemeused byMoldavian andUkrainian geologists [20] the formations of Vendian age aredifferentiated in series which include several beds In normalsequence Moldavian Vendian is composed of OlchedayevBeds (Vol) LomozovBeds (Vlm) Cosauti Beds (Vks) LyadovaBeds (Vld) Bernashevka Beds (Vbrn) Bronnitsa Beds (Vbr)Zincov Beds (Vzn) Dzhurzhevka Beds (Vdz) Kalyus Beds
(Vkl) Pilipy Beds (Vpl) and Shebutintsy Beds (Vsb) Allthese local stratigraphic units are composed of terrigenousvarieties sandstones aleurolites mudstones tuffaceous claystone and greenstones (Table 2)
The majority of layers almost completely can be studiedeither in outcrops in northern part of the republic either inmapping drilling cores dug in areas covered by PaleozoicMesozoic and Cainozoic formations
In the region between Dniester and Prut Rivers Vendianlayers are laid-down directly in deposit on the surface ofcrystalline basement and the central region of Dniester Riverbasinmdashpartially on the Camenka diabases and Volyn Seriesmicroconglomerates
The lower limit of Vendian Formation in the Dniesterriver region has a dipping oriented to southwest (210ndash220∘)and dipping angle varies around the 401015840 (Figure 3) It shouldbe mentioned that the basement relief can be observed ingeomorphologic elements that are in direct connection withthe principal faults in the Dniester region The upper limitof Vendian Formation in the Podolian Tectonic Zone with asmall dipping to southndashsouth-western is disposed practicallyhorizontally and in the south-western of mentioned territoryin this chapter the lower limit is the same direction southndashsouth-western dipping with an angle about 201015840ndash301015840 By thissmall difference between the dipping angles of geological
Advances in Geology 9
Table2Ve
ndianageb
edsinthec
entralregion
oftheD
niesterR
iver
basin
Serie
sFo
rmations
Theb
eds(localstratigraph
icindices)
microfossilsv
arieties
(thickn
essinmeters)
Thea
verage
concentrations
ofΣRE
(La+
Ce+
Y)lowast
gt
dataarefrom
[7]
Kanilovka
Danilo
vka
Vdn
ShebutintsyB
eds(V
sb)mud
stonesa
ndbrow
nandredd
ish-brownaleurolites
with
sand
stone
intercalationsK
aniloviainsolatia
AJistVend
otaeniaantiq
uaGn
il(17ndash43
m)
54
Pilip
yBe
ds(V
pl)mud
stonesa
ndgreenish
gray
aleurolites
with
sand
stone
intercalations
Vend
otaeniaantiq
uaGn
il(18ndash38
m)
45
Mogilev-Po
dolsk
y
Nagoryany
Vng
Kalyu
sBeds(V
kl)dark
gray
with
brow
nnu
ance
mud
stonesph
osph
oriticc
oncretionscarbo
nate
inclu
sions
with
cone-in
-con
etextureV
endotaeniaantiq
uaGn
ilFu
sosqua
mulaAss
Pilitela
Ass
(55ndash80
m)
58
Dzhurzhevka
Beds
(Vdz)sand
stone
rhythm
icstratifi
catio
nsaleurolitesa
ndmud
stones
Nemiana
simplex
PalVend
otaeniaantiq
uaGn
il(10ndash
25m)
53
Jaryshev
Vjr
Zincov
Beds
(Vzn)mud
stonesrhythmicstratifi
catio
nswith
aleurolitessandstone
intercalations
(15ndash20
m)
60
Bron
nitsaB
eds(V
br)mud
stonesa
ndtuffaceou
sclaystonesgreenstonesw
ithmottledmud
stone
intercalationsB
ronicella
podolicaZa
ica-N
ov(20ndash25m
)64
Bernashe
vkaB
eds(V
brn)sandstonesw
ithmud
stone
intercalationsT
irasia
nadiscifarm
isPa
lEo
holin
iamasquensis
Gnill(5ndash20
m)
67
Mogilev
Vmg
Lyad
ovaB
eds(V
ld)mud
stonesa
ndgreensand
yaleurolitesgreensto
nesredd
ishtuffaceou
scla
ystonesin
theu
pper
levelsmdash
sand
stone
intercalationsLjadova
perjo
rata
Ass(20ndash
25m)
38
Cosau
tiBe
ds(V
ks)sand
stonesw
ithrare
gritstone
intercalations
andaleurolitesN
emiana
simplex
Pal(10ndash
18m)
65
Lomozov
Beds
(Vlm)mud
stonesw
ithaleurolites
andsand
stone
intercalations(0ndash
8m)
94Olcheda
yevB
eds(V
ol)theu
pper
levelsmdash
sand
stone
with
aleurolites
intercalationsthe
lower
levelsmdash
gritstone
with
desand
stone
insm
allsgrains
andmud
stone
intercalations(10ndash35m
)72
Volyn
Camenka
R()
Greenish
gray
aphyric
Diaba
sesw
itham
ygdaleform
impregnatio
nsof
plagiocla
se(1ndash
35m)
Soroca
Bedscon
glom
eratesm
icrocong
lomeratesarkoses
andstones(0ndash
10m)
AR-PR
1Cr
ystalline
basementrocksgneiss
escrystallin
eschistsplagiogranitesplagiomigmatites
enderbitesleucogranitesalaskites
lowast
Incompleted
atao
fspectrographica
nalysisthe
northern
partof
marketterritoryin
theF
igure1
10 Advances in Geology
limits is explained the slow increase of the thickness ofVendian Formation that in immediate nearness of Predo-brogean Depression exceeds 750ndash800 meters In contrastwith lower limit the surface of upper limit of Vendian wassubjected to relatively poor processes of denudation whichchanged the morphostructural aspect appeared after the endof sedimentogenesis processes
As a result of geochemical investigations it was estab-lished that in the lower layers of Vendian Formation theconcentration of RE elements compared with layers of upperlevels is relatively higher (Table 2) In particular it refers toOlchedayev Lomozov and Cosauti Beds of Mogilev Forma-tion For example in the southern part of the territory inOlchedayev Beds was detected an anomalous zone with quitehigh concentrations 119862La = 01 and 119862Ce = 008 [10] whichexceed the geochemical background that is approximately thesame as for Lanthanum and for Cerium
In terms of perspective of detecting some significantconcentrations of RE elements as a result of formationof mechanical aureoles consisting of zircon and mon-azite Olchedayev Lomozov and Cosauti beds represent anobject for much more detailed geological and geochemicalresearches
Olchedayev beds are composed by detrital sedimentaryrocks in big grains (varieties of conglomerates microcon-glomerates and sandstones) and mudstones or sandy mud-stones present in the layerrsquos body in form of relatively shallowintercalations
Geological section of Olchedayev beds is not stablethroughout the whole distribution area but in terms oflithological varieties which form layers and the complexstratifications of this local stratigraphic unit it is observed arelatively constant accordance in the lower levels are presentmicroconglomerates and in the upper onesmdashgritstone inbig grains Specific for Olchedayev layers is the presenceof a layer of clays and sandy clays which separate themicroconglomerates from gritstone
Geological section of Olchedayev beds constructed onbasis of mapping drillings in the southern part of the markedterritory in Figure 1 is presented in the following way
Directly on the altered surface of diabases of CamenkaFormation or on crystalline basement surface crust practi-cally devoid of erosion crust are laid-down
(1) Microconglomerates of brown color with angulargrains of quartz potash feldspar and diabases (up to20ndash25) the color is imposed by clayish cement richin iron hydroxides the thickness of this basal layervaries around 4 meters
(2) Rhythmic intercalations of arkose microconglomer-ates with sandstones in various grain of gray or gray-green color in both lithological varieties are presentinclusions of sandy clay stones and clay stones layerthicknessmdashabout 7 meters
(3) Dark gray microconglomerates with clastic grainsof quartz and potash feldspar microconglomeratecement is clayish and their thickness is 1 meter
(4) Greenish-brown and brown mudstones with thinintercalations of fines sandstone and sandy clay stonethickness 45 meters
(5) Gray and gray-reddish arkose gritstones with isolatedinclusions of quartz and potash feldspar (some grainsreach up to 5 millimeters in diameter) between thesandstones are found rare and thin intercalationsof dark gray mudstones thickness average about 7meters
(6) Gritstones of dark gray color with clayish cementthickness not exceeding 4 meters
(7) Quartz-feldspar gray and light gray sandstones indifferent grain including coarse grains are visiblehorizontal and oblique stratifications of differentgranular fractions sandstone thickness 50 meterson the quartz-feldspar sandstones are laid-down theLomozov Beds
The most common thickness of Olchedayev layers variesaround 25 meters
Sandstones and gritstones of Olchedayev Beds in theupper regions of geological section are of light gray colorIn lower areas depending on potash feldspar quantitiesthe color has reddish hues In microscopic sections areobserved sabulous silitic or mixed structures (sabulous-silitic) cement structure is silitic In terms of compositionthe rocks range from quartzose and arkose varieties Amountof feldspars (potash feldspar prevailed) in most cases doesnot exceed 50 by volume Both in the microconglomerates(also highlighted) and in the sandstones are frequent isolatedgrains of quartzite and rocks of crystalline basement In thelower levels of Olchedayev layers are found frequently smallscales of biotite
The degree of grains rounding from which are formedthe terrigenous rocks varieties of Olchedayev increases withtheir size coarse grains are round and smooth small grainsare ragged Often microconglomerates cement is amorphousmass clayish which together with rock grains imposedporosity quite evident
Accessory minerals in small quantities are presented bygarnet zircon and monazite A minus of geological researchcarried out in the mentioned region in this chapter consistedin that a mineralogical analysis which would determine thequantitative relations between zircon and monazite was notachieved As we have remarked the origin of mineralizationrich in RE elements in geological formations from the Dni-ester basin region is a great problem Additional informationwhich would facilitate the solving of this problem wouldpresent the thorough study of the separate grains of zirconandmonazite from the structure and composition andwouldbe extremely important in terms of geochronology It ispossible that the absolute ages of zircon and monazite shouldcoincide with the ages of these minerals found in crystallineformations of basement It did not exclude the case that theseminerals are different as assortment of isomorphic elementsin their chemical composition Such research are importantfor solving of various fundamental and practical geologicalproblems which can determine the origin of zircon and
Advances in Geology 11
monazite the sedimentogenes processes and the formationof mechanical aureoles with significant concentrations ofuseful components Unfortunately because of changes thathave intervened in the last decade of the past century in theRepublic of Moldova all expensive geological research wassuspended
In the Olchedayev rocks are found rare impregnationsof galena barite fluorite and xenotime (YPO
4) Because
monazite and zircon are contained isomorphic impurities ofTh and U and xenotimemdashabout 5 UO
2mdashOlchedayev Beds
are characterized by a relatively high radioactivity whichrarely reaches up to 500 and 780 micronshour
Lomozov beds are formed preponderant frommudstonesa dark gray color with mica they are intercalations ofsandstones finely dispersed The layers thickness has notbeen exceeding 5 meters In some places Lomozov rocks aremissing At level of Lomozov Beds is identified a complexlayer composed of very fine stratifications of fine-grainedsandstone and of dark gray mudstones relatively rich inminerals containingRE Because the average concentration ofLa + Ce + Y amount compared to other Vendian stratifica-tions is the largestmdash94 gt (Table 2)
The mudstones consisted of an amorphous mass ofgray color and in microscopic sections brown color withabundant additions of small scales of hydromica disposedparallel with surfaces of sedimentation On the fund of thisbasedmass are detected small granules (silitic) of quartz withangular forms In Lomozov Beds have a specific character inthe mudstones composition are often presented inclusions ofbiotite and more rarely of muscovite as elongated scales
Cosauti Beds in lithological point of view of this localstratigraphic unit are relatively homogeneous and are com-posed almost solely of sandstone Dark mudstone interca-lations and dispersed fine sandstone are marked only inpatches Cosauti sandstones have white color with sugaraspect in a homogeneous medium or small grain
In microscopic sections sandstones are psammitic clearstructure Aleurite fraction (01 millimeters) is about 5by rock volume (rarelymdash10ndash12) Large grains of quartzare frequent (about 2 millimeters) embedded in argillite-sandy mass (a few tenths of a percent) but in granulometricpoint of view sandstone are very well sorted In the Cosautibeds were discovered sandstone consist not only of quartzgrains Quartzose varieties usually contain about 10 ofdetrital material consisting of other minerals The quartz-feldspar and arkose sandstones are predominated in whichthe feldspar grains scant of above 20 (potassium feldsparis prevailing) It is common inclusions of biotite in the formof scales about 1-2 from volume Less commonly in therock small granules of quartzite are found In small isolatedgranules can be identified pyrite and magnetite Accessoryminerals are more frequent in zircon and monazite whichgenerated geochemical anomalies with relatively high con-centrations of REE
Cement of Cosauti sandstones is relatively variedchlorite-hydromicaceous (sometimes with added of kaolin ordikkite) silica or carbonated in which predominated calciteThe thickness of Cosauti Beds varies between 10 and 18meters
Compared with Olchedayev and Lomozov Beds variedby mineralogical and granulometric composition Vendiansection above Cosauti sandstones are relatively homogeneouson all distribution area A certain practical interest wouldpresent the mudstones of Kalyus Beds rich in phosphoriticconcretions
The morphostructure of Olchedayev Lomozov andCosauti beds succession (Vol + Vlm + Vks) in the Dniesterregion are presented quite homogeneous In terms oftectonic the main structural element within the mentionedterritory in this paper are presented by a segment of PodolianFaults Zone oriented in north-western direction and calledby autochthon geologists Dniester Fault (Figure 1) Effusionmagmatism with alkaline lava flows were distinguished thebeginning of a continental riftogenesis which was manifestedin later Proterozoic As a result of geological mapping ithas been shown that the basement along the Dniester Riverhas a narrow linear structure with typical features of riftvalley in which vertical dislocations amplitudes of basementblocks varies within 20ndash60m [2 3 7 10 18] Completed bythe Camenka diabase this structure in sedimentary coverlayers does not reflect practically anything This is observedby comparison of the crystalline basement relief shown inFigure 2 with the surface of lower limit of Vendian Formation(Figure 4) the latter being much smoother The crystallinebasement relief and the surface of lower limit of VendianFormation are observed linear zones oriented in transversaldirections Dniester Fault which occurred in result of thetectonic process much earliermdashin the south-west of pericra-tonic zone of the East European Platform late Archean wasformed a several tectonic faults oriented in preponderantlynorth-eastern direction [10] Perhaps along these faults hadoccurred more intensive erosion processes that had been ledto digging in the Archean relief negative linear forms
In the following way is explained the morphostructuralaspect of the succession beds which are at Vendian basedin the central region of the Dniester River basin Examiningthe summary thickness of Olchedayev Lomozov andCosautiBeds we see a series of relatively isometric areas whichhave comparatively larger thickness which is in correlationwith some earlier faults (Archean) in the region (Figure 4)Accordingly we conclude that the geological research indetection purpose of eventual essential accumulation of REelements should be continued in these areas with relativelylarger thickness of Vendian basal layers
5 Conclusion
(1) As a result of geological mapping in the basal layersof Moldavian Vendian at accessible depths for an eventualexploitation has been located REE mineralization At thesame time the prospect of these layers in the detection pointof view of some industrial accumulations of ores so far nothas been resolved Consequently in the opinion of manyexplorers studying of Vendian rocks needs to be continueduntil getting a univocal solution
(2) In terms of the geological formations of the centralregion of the Dniester river basin the minerals presenteda practical interest in terms of the formation of significant
12 Advances in Geology
0 10 20
(km)
The lower layers of platform cover
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of lower limit of the Vendian formation (m)
Distribution area of Camenka formation
minus160 minus120
minus140
minus80
minus80
minus60
minus40
0
20
30
30
30
40
40
40
40
40
40
40
40
40
50
50
50
50
50
50
50
60
60
60
60
60
80
Olchedayev-Vol Lomozov-Vlm Cosauti-Vks
Isopachites of lower Vendian layers (Vol + Vlm + Vks ) (m)
Figure 4 The lower layers of platform cover Olchedayev (Vol) Lomozov (Vlm) and Cosauti (Vks) Beds in the central region of the DniesterRiver basin [13]
accumulation of RE elements (Sc Y La Ce and Yb) aremonazite (phosphate) and zircon (silicate) probably zirconand monazite are paragenetically associated
(3) In order to locate in the underground space geo-chemical aureoles of the elements mentioned above it isnecessary to study carefully the conditions of migration andconcentration of these elements in diverse mineralogenesprocesses in conditions of the Dniester River basinmdashin theprogressive and retrograde metamorphism ultrametamor-phism metasomatic processes and training processes of thebasal layers of platform cover
(4) Based on the geological and geochemical data accu-mulated in the geological mapping to outline geochemicalaureoles and anomalies which may serve as a direct indexof the presence in crystalline and sedimentary formations ofmechanical aureoles of monazite and (or) zircon
(5) Geological research in detection purpose of eventualessential accumulation of RE elements in central region ofthe Dniester River basin should be continued in relativelylarger thickness of Vendian basal layers the OlchedayevLomozov and Cosauti Beds oriented along the Archean-Proterozoic tectonic faults
(6)The geochemical study of RE elements has remarkableimportance in interpretation and restoration of geological
processes of the geological past Because of this it is importantto investigate concentrations of these elements in differentvarieties of rocks of different ages and origins In particular itis important to establish particular paragenetic types betweenRE elements and other associated minerals to solve thegeological genetically problems
(i) to establish correlative links between particular typesof RE elements and particular types of crystalline orsedimentary rocks
(ii) to determine the origin of rocks which contain theseelements (formed in a single magmatic process in acommon metamorphic facies and in a single sedi-mentogenesis cycle)
If the detection of a deposit of zircon and monazite con-taining rare earths brings a direct practical result geochem-ical study of any region of the earth crust is of high particularimportance in geological prospection Because it solves agreat problem regarding the determination of parageneticassociations of minerals and chemical elements to determinethe type of petrographic provinces specifies geotectonicappearance of territories and to determine the links betweenlithogenic processes and palaeogeographic conditions in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Applied ampEnvironmentalSoil Science
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Mining
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OceanographyInternational Journal of
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Journal ofPetroleum Engineering
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GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Atmospheric SciencesInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
OceanographyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
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MineralogyInternational Journal of
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ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Geological ResearchJournal of
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Geology Advances in
Advances in Geology 7
The distribution area of Camenka formation
Central region of the Dniester River basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of crystalline basement surface (m)Isopachites of Camenka formation (m)
0 10 20
(km) minus280
minus240
minus160
20
40minus140minus260
minus200
minus180
minus160
minus80
minus80
60
minus60
minus200
minus100minus140 1
0
10
10
10
10
10
20
20
20
20
20
20
20
20
20
20
minus40
minus20
minus20
0
30
0
0
30
30
80
Figure 2 The distribution area of Camenka Formation in the central region of the Dniester River basin [13]
aspect is relatively narrow (8ndash10 kilometers in cross section)is oriented in a north-western direction and covers thelinear-depressive zone of Dniester Fault (Figure 2) We canassume that the centers of lenticular forms coincide withchannels throughwhich on the earth surface poured lavawithalkaline composition specific for early stages of continentalriftogenesisThe phenomenon took place in later Proterozoicin one of the last phases of tectonic activity in south-westernareas of the East European Platform
Camenka Formation consists of diabases and a basal layerof microconglomerates and conglomerates (Soroca Beds)
Lithological varieties of Soroca in the spread region ofFormation Camenka do not present an integral structuralunit Firstly these lithological varieties are in deposits just inthe spread zone of diabases and only in someplaces vulcanitesof Camenka Formation are laid-down directly in depositon the surface of crystalline basement Perhaps Sorocabasal beds in the mentioned region had had a much largespread but because of denudation processes were preservedonly under diabases Thickness of Soroca Beds crossed bydrilling mapping varies from 05 to 35 meters Rocks aredistinguished by their mineralogical composition and areformed from an unselected rubbly material conglomeratesconglomerate-breccias microconglomerates (predominant)coarse-grained sandstones and arkose sandstones (rarely)
The rubbly material is presented by slightly rounded grainsof crystalline basement rocksmdashquartzite potash feldsparand biotite scales cemented with a brown argilitic materialCement volume typically exceeds 50 by volume In thefollowing way most of Soroca Bedsrsquo rocks differ by theirspecific brown color
Arkose sandstones and microconglomerates that can befound in the composition of the basal layers of Camenka For-mation are massive rocks hard of gray-green or pink-graycolor have sabulous structures and consist of plagioclase (upto 50ndash60) potash feldspar (up to 15) quartz (25 to 35)cement and grains of basement rocks
In clastic material are prevalent semirounded or ruggedforms and grainsrsquo sizes range from 10ndash15 millimeters(microconglomerates) 10ndash01 millimeters (sandstones)01 millimeters (sandy mudstones) Cement has a highporosity and has a kaolin-hydromicaceous kaolin-chlorite-hydromicaceous or kaolin composition
From accessory minerals are present small grains ofgarnet zircon monazite apatite and titanomagnetite
The rocks of Soroca Beds have a specific radioactivity rel-atively high (30ndash35 micronshour) imposed by the presenceof isomorphic thorium in the monazite composition
Based on geochemical investigations of Sorocamicrocon-glomerate were found relatively high concentrations of La
8 Advances in Geology
0 10 20
(km)
The morfostructure of Vendian formation
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isopachites of Vendian layers (m)Isohypses of upper limit of the Vendian formation (m)
minus80
minus60
minus40
minus20
minus20
0
0
0
20
20
20
20
40
40
40
40
60
60
60
60
80
80
80
80
100
100
100
120
120
120
140
140
140
160
160
160
180
180
180
180
180
200
200
200
200
200
200
220
220
220
220
220
240
240
240
240
240
260
260
260
280
280
280300
Figure 3 The morphostructure of Vendian Formation in the central region of the Dniester River basin [13]
Diabases predominate in Camenka Formation and inaxial zone of the banded body exceed the thickness of 30ndash40m In macroscopic point of view diabases are compactvolcanogenic rocks of a dark gray gray-brown or darkgreenish color with a relatively high specific weight Theirstructure is cryptocrystalline or crystalline in very smallgrains Between diabases discovered in the Dniester areathere are two varietiesmdashaphyric diabase and diabase withan apparently porphyric texture Usually porphyric inclu-sions have various sizes (1ndash15 millimeters) and consist ofcalcite and rarely chlorite Most diabases have an ophyticstructure and massive texture and in their composition areincluded basic plagioclase (40ndash50) monoclinic pyroxene(5ndash19) chlorite (30ndash35) epidote (3ndash7) and titanomag-netite (5ndash10)Theminerals which contained RE elements inCamenka Formation were not detected
43 Terrigenous Layers from the Vendian Lower LevelAccording to the stratigraphic schemeused byMoldavian andUkrainian geologists [20] the formations of Vendian age aredifferentiated in series which include several beds In normalsequence Moldavian Vendian is composed of OlchedayevBeds (Vol) LomozovBeds (Vlm) Cosauti Beds (Vks) LyadovaBeds (Vld) Bernashevka Beds (Vbrn) Bronnitsa Beds (Vbr)Zincov Beds (Vzn) Dzhurzhevka Beds (Vdz) Kalyus Beds
(Vkl) Pilipy Beds (Vpl) and Shebutintsy Beds (Vsb) Allthese local stratigraphic units are composed of terrigenousvarieties sandstones aleurolites mudstones tuffaceous claystone and greenstones (Table 2)
The majority of layers almost completely can be studiedeither in outcrops in northern part of the republic either inmapping drilling cores dug in areas covered by PaleozoicMesozoic and Cainozoic formations
In the region between Dniester and Prut Rivers Vendianlayers are laid-down directly in deposit on the surface ofcrystalline basement and the central region of Dniester Riverbasinmdashpartially on the Camenka diabases and Volyn Seriesmicroconglomerates
The lower limit of Vendian Formation in the Dniesterriver region has a dipping oriented to southwest (210ndash220∘)and dipping angle varies around the 401015840 (Figure 3) It shouldbe mentioned that the basement relief can be observed ingeomorphologic elements that are in direct connection withthe principal faults in the Dniester region The upper limitof Vendian Formation in the Podolian Tectonic Zone with asmall dipping to southndashsouth-western is disposed practicallyhorizontally and in the south-western of mentioned territoryin this chapter the lower limit is the same direction southndashsouth-western dipping with an angle about 201015840ndash301015840 By thissmall difference between the dipping angles of geological
Advances in Geology 9
Table2Ve
ndianageb
edsinthec
entralregion
oftheD
niesterR
iver
basin
Serie
sFo
rmations
Theb
eds(localstratigraph
icindices)
microfossilsv
arieties
(thickn
essinmeters)
Thea
verage
concentrations
ofΣRE
(La+
Ce+
Y)lowast
gt
dataarefrom
[7]
Kanilovka
Danilo
vka
Vdn
ShebutintsyB
eds(V
sb)mud
stonesa
ndbrow
nandredd
ish-brownaleurolites
with
sand
stone
intercalationsK
aniloviainsolatia
AJistVend
otaeniaantiq
uaGn
il(17ndash43
m)
54
Pilip
yBe
ds(V
pl)mud
stonesa
ndgreenish
gray
aleurolites
with
sand
stone
intercalations
Vend
otaeniaantiq
uaGn
il(18ndash38
m)
45
Mogilev-Po
dolsk
y
Nagoryany
Vng
Kalyu
sBeds(V
kl)dark
gray
with
brow
nnu
ance
mud
stonesph
osph
oriticc
oncretionscarbo
nate
inclu
sions
with
cone-in
-con
etextureV
endotaeniaantiq
uaGn
ilFu
sosqua
mulaAss
Pilitela
Ass
(55ndash80
m)
58
Dzhurzhevka
Beds
(Vdz)sand
stone
rhythm
icstratifi
catio
nsaleurolitesa
ndmud
stones
Nemiana
simplex
PalVend
otaeniaantiq
uaGn
il(10ndash
25m)
53
Jaryshev
Vjr
Zincov
Beds
(Vzn)mud
stonesrhythmicstratifi
catio
nswith
aleurolitessandstone
intercalations
(15ndash20
m)
60
Bron
nitsaB
eds(V
br)mud
stonesa
ndtuffaceou
sclaystonesgreenstonesw
ithmottledmud
stone
intercalationsB
ronicella
podolicaZa
ica-N
ov(20ndash25m
)64
Bernashe
vkaB
eds(V
brn)sandstonesw
ithmud
stone
intercalationsT
irasia
nadiscifarm
isPa
lEo
holin
iamasquensis
Gnill(5ndash20
m)
67
Mogilev
Vmg
Lyad
ovaB
eds(V
ld)mud
stonesa
ndgreensand
yaleurolitesgreensto
nesredd
ishtuffaceou
scla
ystonesin
theu
pper
levelsmdash
sand
stone
intercalationsLjadova
perjo
rata
Ass(20ndash
25m)
38
Cosau
tiBe
ds(V
ks)sand
stonesw
ithrare
gritstone
intercalations
andaleurolitesN
emiana
simplex
Pal(10ndash
18m)
65
Lomozov
Beds
(Vlm)mud
stonesw
ithaleurolites
andsand
stone
intercalations(0ndash
8m)
94Olcheda
yevB
eds(V
ol)theu
pper
levelsmdash
sand
stone
with
aleurolites
intercalationsthe
lower
levelsmdash
gritstone
with
desand
stone
insm
allsgrains
andmud
stone
intercalations(10ndash35m
)72
Volyn
Camenka
R()
Greenish
gray
aphyric
Diaba
sesw
itham
ygdaleform
impregnatio
nsof
plagiocla
se(1ndash
35m)
Soroca
Bedscon
glom
eratesm
icrocong
lomeratesarkoses
andstones(0ndash
10m)
AR-PR
1Cr
ystalline
basementrocksgneiss
escrystallin
eschistsplagiogranitesplagiomigmatites
enderbitesleucogranitesalaskites
lowast
Incompleted
atao
fspectrographica
nalysisthe
northern
partof
marketterritoryin
theF
igure1
10 Advances in Geology
limits is explained the slow increase of the thickness ofVendian Formation that in immediate nearness of Predo-brogean Depression exceeds 750ndash800 meters In contrastwith lower limit the surface of upper limit of Vendian wassubjected to relatively poor processes of denudation whichchanged the morphostructural aspect appeared after the endof sedimentogenesis processes
As a result of geochemical investigations it was estab-lished that in the lower layers of Vendian Formation theconcentration of RE elements compared with layers of upperlevels is relatively higher (Table 2) In particular it refers toOlchedayev Lomozov and Cosauti Beds of Mogilev Forma-tion For example in the southern part of the territory inOlchedayev Beds was detected an anomalous zone with quitehigh concentrations 119862La = 01 and 119862Ce = 008 [10] whichexceed the geochemical background that is approximately thesame as for Lanthanum and for Cerium
In terms of perspective of detecting some significantconcentrations of RE elements as a result of formationof mechanical aureoles consisting of zircon and mon-azite Olchedayev Lomozov and Cosauti beds represent anobject for much more detailed geological and geochemicalresearches
Olchedayev beds are composed by detrital sedimentaryrocks in big grains (varieties of conglomerates microcon-glomerates and sandstones) and mudstones or sandy mud-stones present in the layerrsquos body in form of relatively shallowintercalations
Geological section of Olchedayev beds is not stablethroughout the whole distribution area but in terms oflithological varieties which form layers and the complexstratifications of this local stratigraphic unit it is observed arelatively constant accordance in the lower levels are presentmicroconglomerates and in the upper onesmdashgritstone inbig grains Specific for Olchedayev layers is the presenceof a layer of clays and sandy clays which separate themicroconglomerates from gritstone
Geological section of Olchedayev beds constructed onbasis of mapping drillings in the southern part of the markedterritory in Figure 1 is presented in the following way
Directly on the altered surface of diabases of CamenkaFormation or on crystalline basement surface crust practi-cally devoid of erosion crust are laid-down
(1) Microconglomerates of brown color with angulargrains of quartz potash feldspar and diabases (up to20ndash25) the color is imposed by clayish cement richin iron hydroxides the thickness of this basal layervaries around 4 meters
(2) Rhythmic intercalations of arkose microconglomer-ates with sandstones in various grain of gray or gray-green color in both lithological varieties are presentinclusions of sandy clay stones and clay stones layerthicknessmdashabout 7 meters
(3) Dark gray microconglomerates with clastic grainsof quartz and potash feldspar microconglomeratecement is clayish and their thickness is 1 meter
(4) Greenish-brown and brown mudstones with thinintercalations of fines sandstone and sandy clay stonethickness 45 meters
(5) Gray and gray-reddish arkose gritstones with isolatedinclusions of quartz and potash feldspar (some grainsreach up to 5 millimeters in diameter) between thesandstones are found rare and thin intercalationsof dark gray mudstones thickness average about 7meters
(6) Gritstones of dark gray color with clayish cementthickness not exceeding 4 meters
(7) Quartz-feldspar gray and light gray sandstones indifferent grain including coarse grains are visiblehorizontal and oblique stratifications of differentgranular fractions sandstone thickness 50 meterson the quartz-feldspar sandstones are laid-down theLomozov Beds
The most common thickness of Olchedayev layers variesaround 25 meters
Sandstones and gritstones of Olchedayev Beds in theupper regions of geological section are of light gray colorIn lower areas depending on potash feldspar quantitiesthe color has reddish hues In microscopic sections areobserved sabulous silitic or mixed structures (sabulous-silitic) cement structure is silitic In terms of compositionthe rocks range from quartzose and arkose varieties Amountof feldspars (potash feldspar prevailed) in most cases doesnot exceed 50 by volume Both in the microconglomerates(also highlighted) and in the sandstones are frequent isolatedgrains of quartzite and rocks of crystalline basement In thelower levels of Olchedayev layers are found frequently smallscales of biotite
The degree of grains rounding from which are formedthe terrigenous rocks varieties of Olchedayev increases withtheir size coarse grains are round and smooth small grainsare ragged Often microconglomerates cement is amorphousmass clayish which together with rock grains imposedporosity quite evident
Accessory minerals in small quantities are presented bygarnet zircon and monazite A minus of geological researchcarried out in the mentioned region in this chapter consistedin that a mineralogical analysis which would determine thequantitative relations between zircon and monazite was notachieved As we have remarked the origin of mineralizationrich in RE elements in geological formations from the Dni-ester basin region is a great problem Additional informationwhich would facilitate the solving of this problem wouldpresent the thorough study of the separate grains of zirconandmonazite from the structure and composition andwouldbe extremely important in terms of geochronology It ispossible that the absolute ages of zircon and monazite shouldcoincide with the ages of these minerals found in crystallineformations of basement It did not exclude the case that theseminerals are different as assortment of isomorphic elementsin their chemical composition Such research are importantfor solving of various fundamental and practical geologicalproblems which can determine the origin of zircon and
Advances in Geology 11
monazite the sedimentogenes processes and the formationof mechanical aureoles with significant concentrations ofuseful components Unfortunately because of changes thathave intervened in the last decade of the past century in theRepublic of Moldova all expensive geological research wassuspended
In the Olchedayev rocks are found rare impregnationsof galena barite fluorite and xenotime (YPO
4) Because
monazite and zircon are contained isomorphic impurities ofTh and U and xenotimemdashabout 5 UO
2mdashOlchedayev Beds
are characterized by a relatively high radioactivity whichrarely reaches up to 500 and 780 micronshour
Lomozov beds are formed preponderant frommudstonesa dark gray color with mica they are intercalations ofsandstones finely dispersed The layers thickness has notbeen exceeding 5 meters In some places Lomozov rocks aremissing At level of Lomozov Beds is identified a complexlayer composed of very fine stratifications of fine-grainedsandstone and of dark gray mudstones relatively rich inminerals containingRE Because the average concentration ofLa + Ce + Y amount compared to other Vendian stratifica-tions is the largestmdash94 gt (Table 2)
The mudstones consisted of an amorphous mass ofgray color and in microscopic sections brown color withabundant additions of small scales of hydromica disposedparallel with surfaces of sedimentation On the fund of thisbasedmass are detected small granules (silitic) of quartz withangular forms In Lomozov Beds have a specific character inthe mudstones composition are often presented inclusions ofbiotite and more rarely of muscovite as elongated scales
Cosauti Beds in lithological point of view of this localstratigraphic unit are relatively homogeneous and are com-posed almost solely of sandstone Dark mudstone interca-lations and dispersed fine sandstone are marked only inpatches Cosauti sandstones have white color with sugaraspect in a homogeneous medium or small grain
In microscopic sections sandstones are psammitic clearstructure Aleurite fraction (01 millimeters) is about 5by rock volume (rarelymdash10ndash12) Large grains of quartzare frequent (about 2 millimeters) embedded in argillite-sandy mass (a few tenths of a percent) but in granulometricpoint of view sandstone are very well sorted In the Cosautibeds were discovered sandstone consist not only of quartzgrains Quartzose varieties usually contain about 10 ofdetrital material consisting of other minerals The quartz-feldspar and arkose sandstones are predominated in whichthe feldspar grains scant of above 20 (potassium feldsparis prevailing) It is common inclusions of biotite in the formof scales about 1-2 from volume Less commonly in therock small granules of quartzite are found In small isolatedgranules can be identified pyrite and magnetite Accessoryminerals are more frequent in zircon and monazite whichgenerated geochemical anomalies with relatively high con-centrations of REE
Cement of Cosauti sandstones is relatively variedchlorite-hydromicaceous (sometimes with added of kaolin ordikkite) silica or carbonated in which predominated calciteThe thickness of Cosauti Beds varies between 10 and 18meters
Compared with Olchedayev and Lomozov Beds variedby mineralogical and granulometric composition Vendiansection above Cosauti sandstones are relatively homogeneouson all distribution area A certain practical interest wouldpresent the mudstones of Kalyus Beds rich in phosphoriticconcretions
The morphostructure of Olchedayev Lomozov andCosauti beds succession (Vol + Vlm + Vks) in the Dniesterregion are presented quite homogeneous In terms oftectonic the main structural element within the mentionedterritory in this paper are presented by a segment of PodolianFaults Zone oriented in north-western direction and calledby autochthon geologists Dniester Fault (Figure 1) Effusionmagmatism with alkaline lava flows were distinguished thebeginning of a continental riftogenesis which was manifestedin later Proterozoic As a result of geological mapping ithas been shown that the basement along the Dniester Riverhas a narrow linear structure with typical features of riftvalley in which vertical dislocations amplitudes of basementblocks varies within 20ndash60m [2 3 7 10 18] Completed bythe Camenka diabase this structure in sedimentary coverlayers does not reflect practically anything This is observedby comparison of the crystalline basement relief shown inFigure 2 with the surface of lower limit of Vendian Formation(Figure 4) the latter being much smoother The crystallinebasement relief and the surface of lower limit of VendianFormation are observed linear zones oriented in transversaldirections Dniester Fault which occurred in result of thetectonic process much earliermdashin the south-west of pericra-tonic zone of the East European Platform late Archean wasformed a several tectonic faults oriented in preponderantlynorth-eastern direction [10] Perhaps along these faults hadoccurred more intensive erosion processes that had been ledto digging in the Archean relief negative linear forms
In the following way is explained the morphostructuralaspect of the succession beds which are at Vendian basedin the central region of the Dniester River basin Examiningthe summary thickness of Olchedayev Lomozov andCosautiBeds we see a series of relatively isometric areas whichhave comparatively larger thickness which is in correlationwith some earlier faults (Archean) in the region (Figure 4)Accordingly we conclude that the geological research indetection purpose of eventual essential accumulation of REelements should be continued in these areas with relativelylarger thickness of Vendian basal layers
5 Conclusion
(1) As a result of geological mapping in the basal layersof Moldavian Vendian at accessible depths for an eventualexploitation has been located REE mineralization At thesame time the prospect of these layers in the detection pointof view of some industrial accumulations of ores so far nothas been resolved Consequently in the opinion of manyexplorers studying of Vendian rocks needs to be continueduntil getting a univocal solution
(2) In terms of the geological formations of the centralregion of the Dniester river basin the minerals presenteda practical interest in terms of the formation of significant
12 Advances in Geology
0 10 20
(km)
The lower layers of platform cover
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of lower limit of the Vendian formation (m)
Distribution area of Camenka formation
minus160 minus120
minus140
minus80
minus80
minus60
minus40
0
20
30
30
30
40
40
40
40
40
40
40
40
40
50
50
50
50
50
50
50
60
60
60
60
60
80
Olchedayev-Vol Lomozov-Vlm Cosauti-Vks
Isopachites of lower Vendian layers (Vol + Vlm + Vks ) (m)
Figure 4 The lower layers of platform cover Olchedayev (Vol) Lomozov (Vlm) and Cosauti (Vks) Beds in the central region of the DniesterRiver basin [13]
accumulation of RE elements (Sc Y La Ce and Yb) aremonazite (phosphate) and zircon (silicate) probably zirconand monazite are paragenetically associated
(3) In order to locate in the underground space geo-chemical aureoles of the elements mentioned above it isnecessary to study carefully the conditions of migration andconcentration of these elements in diverse mineralogenesprocesses in conditions of the Dniester River basinmdashin theprogressive and retrograde metamorphism ultrametamor-phism metasomatic processes and training processes of thebasal layers of platform cover
(4) Based on the geological and geochemical data accu-mulated in the geological mapping to outline geochemicalaureoles and anomalies which may serve as a direct indexof the presence in crystalline and sedimentary formations ofmechanical aureoles of monazite and (or) zircon
(5) Geological research in detection purpose of eventualessential accumulation of RE elements in central region ofthe Dniester River basin should be continued in relativelylarger thickness of Vendian basal layers the OlchedayevLomozov and Cosauti Beds oriented along the Archean-Proterozoic tectonic faults
(6)The geochemical study of RE elements has remarkableimportance in interpretation and restoration of geological
processes of the geological past Because of this it is importantto investigate concentrations of these elements in differentvarieties of rocks of different ages and origins In particular itis important to establish particular paragenetic types betweenRE elements and other associated minerals to solve thegeological genetically problems
(i) to establish correlative links between particular typesof RE elements and particular types of crystalline orsedimentary rocks
(ii) to determine the origin of rocks which contain theseelements (formed in a single magmatic process in acommon metamorphic facies and in a single sedi-mentogenesis cycle)
If the detection of a deposit of zircon and monazite con-taining rare earths brings a direct practical result geochem-ical study of any region of the earth crust is of high particularimportance in geological prospection Because it solves agreat problem regarding the determination of parageneticassociations of minerals and chemical elements to determinethe type of petrographic provinces specifies geotectonicappearance of territories and to determine the links betweenlithogenic processes and palaeogeographic conditions in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Applied ampEnvironmentalSoil Science
Volume 2014
Mining
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OceanographyInternational Journal of
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Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Atmospheric SciencesInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
OceanographyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
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MineralogyInternational Journal of
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MeteorologyAdvances in
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ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Geological ResearchJournal of
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Geology Advances in
8 Advances in Geology
0 10 20
(km)
The morfostructure of Vendian formation
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isopachites of Vendian layers (m)Isohypses of upper limit of the Vendian formation (m)
minus80
minus60
minus40
minus20
minus20
0
0
0
20
20
20
20
40
40
40
40
60
60
60
60
80
80
80
80
100
100
100
120
120
120
140
140
140
160
160
160
180
180
180
180
180
200
200
200
200
200
200
220
220
220
220
220
240
240
240
240
240
260
260
260
280
280
280300
Figure 3 The morphostructure of Vendian Formation in the central region of the Dniester River basin [13]
Diabases predominate in Camenka Formation and inaxial zone of the banded body exceed the thickness of 30ndash40m In macroscopic point of view diabases are compactvolcanogenic rocks of a dark gray gray-brown or darkgreenish color with a relatively high specific weight Theirstructure is cryptocrystalline or crystalline in very smallgrains Between diabases discovered in the Dniester areathere are two varietiesmdashaphyric diabase and diabase withan apparently porphyric texture Usually porphyric inclu-sions have various sizes (1ndash15 millimeters) and consist ofcalcite and rarely chlorite Most diabases have an ophyticstructure and massive texture and in their composition areincluded basic plagioclase (40ndash50) monoclinic pyroxene(5ndash19) chlorite (30ndash35) epidote (3ndash7) and titanomag-netite (5ndash10)Theminerals which contained RE elements inCamenka Formation were not detected
43 Terrigenous Layers from the Vendian Lower LevelAccording to the stratigraphic schemeused byMoldavian andUkrainian geologists [20] the formations of Vendian age aredifferentiated in series which include several beds In normalsequence Moldavian Vendian is composed of OlchedayevBeds (Vol) LomozovBeds (Vlm) Cosauti Beds (Vks) LyadovaBeds (Vld) Bernashevka Beds (Vbrn) Bronnitsa Beds (Vbr)Zincov Beds (Vzn) Dzhurzhevka Beds (Vdz) Kalyus Beds
(Vkl) Pilipy Beds (Vpl) and Shebutintsy Beds (Vsb) Allthese local stratigraphic units are composed of terrigenousvarieties sandstones aleurolites mudstones tuffaceous claystone and greenstones (Table 2)
The majority of layers almost completely can be studiedeither in outcrops in northern part of the republic either inmapping drilling cores dug in areas covered by PaleozoicMesozoic and Cainozoic formations
In the region between Dniester and Prut Rivers Vendianlayers are laid-down directly in deposit on the surface ofcrystalline basement and the central region of Dniester Riverbasinmdashpartially on the Camenka diabases and Volyn Seriesmicroconglomerates
The lower limit of Vendian Formation in the Dniesterriver region has a dipping oriented to southwest (210ndash220∘)and dipping angle varies around the 401015840 (Figure 3) It shouldbe mentioned that the basement relief can be observed ingeomorphologic elements that are in direct connection withthe principal faults in the Dniester region The upper limitof Vendian Formation in the Podolian Tectonic Zone with asmall dipping to southndashsouth-western is disposed practicallyhorizontally and in the south-western of mentioned territoryin this chapter the lower limit is the same direction southndashsouth-western dipping with an angle about 201015840ndash301015840 By thissmall difference between the dipping angles of geological
Advances in Geology 9
Table2Ve
ndianageb
edsinthec
entralregion
oftheD
niesterR
iver
basin
Serie
sFo
rmations
Theb
eds(localstratigraph
icindices)
microfossilsv
arieties
(thickn
essinmeters)
Thea
verage
concentrations
ofΣRE
(La+
Ce+
Y)lowast
gt
dataarefrom
[7]
Kanilovka
Danilo
vka
Vdn
ShebutintsyB
eds(V
sb)mud
stonesa
ndbrow
nandredd
ish-brownaleurolites
with
sand
stone
intercalationsK
aniloviainsolatia
AJistVend
otaeniaantiq
uaGn
il(17ndash43
m)
54
Pilip
yBe
ds(V
pl)mud
stonesa
ndgreenish
gray
aleurolites
with
sand
stone
intercalations
Vend
otaeniaantiq
uaGn
il(18ndash38
m)
45
Mogilev-Po
dolsk
y
Nagoryany
Vng
Kalyu
sBeds(V
kl)dark
gray
with
brow
nnu
ance
mud
stonesph
osph
oriticc
oncretionscarbo
nate
inclu
sions
with
cone-in
-con
etextureV
endotaeniaantiq
uaGn
ilFu
sosqua
mulaAss
Pilitela
Ass
(55ndash80
m)
58
Dzhurzhevka
Beds
(Vdz)sand
stone
rhythm
icstratifi
catio
nsaleurolitesa
ndmud
stones
Nemiana
simplex
PalVend
otaeniaantiq
uaGn
il(10ndash
25m)
53
Jaryshev
Vjr
Zincov
Beds
(Vzn)mud
stonesrhythmicstratifi
catio
nswith
aleurolitessandstone
intercalations
(15ndash20
m)
60
Bron
nitsaB
eds(V
br)mud
stonesa
ndtuffaceou
sclaystonesgreenstonesw
ithmottledmud
stone
intercalationsB
ronicella
podolicaZa
ica-N
ov(20ndash25m
)64
Bernashe
vkaB
eds(V
brn)sandstonesw
ithmud
stone
intercalationsT
irasia
nadiscifarm
isPa
lEo
holin
iamasquensis
Gnill(5ndash20
m)
67
Mogilev
Vmg
Lyad
ovaB
eds(V
ld)mud
stonesa
ndgreensand
yaleurolitesgreensto
nesredd
ishtuffaceou
scla
ystonesin
theu
pper
levelsmdash
sand
stone
intercalationsLjadova
perjo
rata
Ass(20ndash
25m)
38
Cosau
tiBe
ds(V
ks)sand
stonesw
ithrare
gritstone
intercalations
andaleurolitesN
emiana
simplex
Pal(10ndash
18m)
65
Lomozov
Beds
(Vlm)mud
stonesw
ithaleurolites
andsand
stone
intercalations(0ndash
8m)
94Olcheda
yevB
eds(V
ol)theu
pper
levelsmdash
sand
stone
with
aleurolites
intercalationsthe
lower
levelsmdash
gritstone
with
desand
stone
insm
allsgrains
andmud
stone
intercalations(10ndash35m
)72
Volyn
Camenka
R()
Greenish
gray
aphyric
Diaba
sesw
itham
ygdaleform
impregnatio
nsof
plagiocla
se(1ndash
35m)
Soroca
Bedscon
glom
eratesm
icrocong
lomeratesarkoses
andstones(0ndash
10m)
AR-PR
1Cr
ystalline
basementrocksgneiss
escrystallin
eschistsplagiogranitesplagiomigmatites
enderbitesleucogranitesalaskites
lowast
Incompleted
atao
fspectrographica
nalysisthe
northern
partof
marketterritoryin
theF
igure1
10 Advances in Geology
limits is explained the slow increase of the thickness ofVendian Formation that in immediate nearness of Predo-brogean Depression exceeds 750ndash800 meters In contrastwith lower limit the surface of upper limit of Vendian wassubjected to relatively poor processes of denudation whichchanged the morphostructural aspect appeared after the endof sedimentogenesis processes
As a result of geochemical investigations it was estab-lished that in the lower layers of Vendian Formation theconcentration of RE elements compared with layers of upperlevels is relatively higher (Table 2) In particular it refers toOlchedayev Lomozov and Cosauti Beds of Mogilev Forma-tion For example in the southern part of the territory inOlchedayev Beds was detected an anomalous zone with quitehigh concentrations 119862La = 01 and 119862Ce = 008 [10] whichexceed the geochemical background that is approximately thesame as for Lanthanum and for Cerium
In terms of perspective of detecting some significantconcentrations of RE elements as a result of formationof mechanical aureoles consisting of zircon and mon-azite Olchedayev Lomozov and Cosauti beds represent anobject for much more detailed geological and geochemicalresearches
Olchedayev beds are composed by detrital sedimentaryrocks in big grains (varieties of conglomerates microcon-glomerates and sandstones) and mudstones or sandy mud-stones present in the layerrsquos body in form of relatively shallowintercalations
Geological section of Olchedayev beds is not stablethroughout the whole distribution area but in terms oflithological varieties which form layers and the complexstratifications of this local stratigraphic unit it is observed arelatively constant accordance in the lower levels are presentmicroconglomerates and in the upper onesmdashgritstone inbig grains Specific for Olchedayev layers is the presenceof a layer of clays and sandy clays which separate themicroconglomerates from gritstone
Geological section of Olchedayev beds constructed onbasis of mapping drillings in the southern part of the markedterritory in Figure 1 is presented in the following way
Directly on the altered surface of diabases of CamenkaFormation or on crystalline basement surface crust practi-cally devoid of erosion crust are laid-down
(1) Microconglomerates of brown color with angulargrains of quartz potash feldspar and diabases (up to20ndash25) the color is imposed by clayish cement richin iron hydroxides the thickness of this basal layervaries around 4 meters
(2) Rhythmic intercalations of arkose microconglomer-ates with sandstones in various grain of gray or gray-green color in both lithological varieties are presentinclusions of sandy clay stones and clay stones layerthicknessmdashabout 7 meters
(3) Dark gray microconglomerates with clastic grainsof quartz and potash feldspar microconglomeratecement is clayish and their thickness is 1 meter
(4) Greenish-brown and brown mudstones with thinintercalations of fines sandstone and sandy clay stonethickness 45 meters
(5) Gray and gray-reddish arkose gritstones with isolatedinclusions of quartz and potash feldspar (some grainsreach up to 5 millimeters in diameter) between thesandstones are found rare and thin intercalationsof dark gray mudstones thickness average about 7meters
(6) Gritstones of dark gray color with clayish cementthickness not exceeding 4 meters
(7) Quartz-feldspar gray and light gray sandstones indifferent grain including coarse grains are visiblehorizontal and oblique stratifications of differentgranular fractions sandstone thickness 50 meterson the quartz-feldspar sandstones are laid-down theLomozov Beds
The most common thickness of Olchedayev layers variesaround 25 meters
Sandstones and gritstones of Olchedayev Beds in theupper regions of geological section are of light gray colorIn lower areas depending on potash feldspar quantitiesthe color has reddish hues In microscopic sections areobserved sabulous silitic or mixed structures (sabulous-silitic) cement structure is silitic In terms of compositionthe rocks range from quartzose and arkose varieties Amountof feldspars (potash feldspar prevailed) in most cases doesnot exceed 50 by volume Both in the microconglomerates(also highlighted) and in the sandstones are frequent isolatedgrains of quartzite and rocks of crystalline basement In thelower levels of Olchedayev layers are found frequently smallscales of biotite
The degree of grains rounding from which are formedthe terrigenous rocks varieties of Olchedayev increases withtheir size coarse grains are round and smooth small grainsare ragged Often microconglomerates cement is amorphousmass clayish which together with rock grains imposedporosity quite evident
Accessory minerals in small quantities are presented bygarnet zircon and monazite A minus of geological researchcarried out in the mentioned region in this chapter consistedin that a mineralogical analysis which would determine thequantitative relations between zircon and monazite was notachieved As we have remarked the origin of mineralizationrich in RE elements in geological formations from the Dni-ester basin region is a great problem Additional informationwhich would facilitate the solving of this problem wouldpresent the thorough study of the separate grains of zirconandmonazite from the structure and composition andwouldbe extremely important in terms of geochronology It ispossible that the absolute ages of zircon and monazite shouldcoincide with the ages of these minerals found in crystallineformations of basement It did not exclude the case that theseminerals are different as assortment of isomorphic elementsin their chemical composition Such research are importantfor solving of various fundamental and practical geologicalproblems which can determine the origin of zircon and
Advances in Geology 11
monazite the sedimentogenes processes and the formationof mechanical aureoles with significant concentrations ofuseful components Unfortunately because of changes thathave intervened in the last decade of the past century in theRepublic of Moldova all expensive geological research wassuspended
In the Olchedayev rocks are found rare impregnationsof galena barite fluorite and xenotime (YPO
4) Because
monazite and zircon are contained isomorphic impurities ofTh and U and xenotimemdashabout 5 UO
2mdashOlchedayev Beds
are characterized by a relatively high radioactivity whichrarely reaches up to 500 and 780 micronshour
Lomozov beds are formed preponderant frommudstonesa dark gray color with mica they are intercalations ofsandstones finely dispersed The layers thickness has notbeen exceeding 5 meters In some places Lomozov rocks aremissing At level of Lomozov Beds is identified a complexlayer composed of very fine stratifications of fine-grainedsandstone and of dark gray mudstones relatively rich inminerals containingRE Because the average concentration ofLa + Ce + Y amount compared to other Vendian stratifica-tions is the largestmdash94 gt (Table 2)
The mudstones consisted of an amorphous mass ofgray color and in microscopic sections brown color withabundant additions of small scales of hydromica disposedparallel with surfaces of sedimentation On the fund of thisbasedmass are detected small granules (silitic) of quartz withangular forms In Lomozov Beds have a specific character inthe mudstones composition are often presented inclusions ofbiotite and more rarely of muscovite as elongated scales
Cosauti Beds in lithological point of view of this localstratigraphic unit are relatively homogeneous and are com-posed almost solely of sandstone Dark mudstone interca-lations and dispersed fine sandstone are marked only inpatches Cosauti sandstones have white color with sugaraspect in a homogeneous medium or small grain
In microscopic sections sandstones are psammitic clearstructure Aleurite fraction (01 millimeters) is about 5by rock volume (rarelymdash10ndash12) Large grains of quartzare frequent (about 2 millimeters) embedded in argillite-sandy mass (a few tenths of a percent) but in granulometricpoint of view sandstone are very well sorted In the Cosautibeds were discovered sandstone consist not only of quartzgrains Quartzose varieties usually contain about 10 ofdetrital material consisting of other minerals The quartz-feldspar and arkose sandstones are predominated in whichthe feldspar grains scant of above 20 (potassium feldsparis prevailing) It is common inclusions of biotite in the formof scales about 1-2 from volume Less commonly in therock small granules of quartzite are found In small isolatedgranules can be identified pyrite and magnetite Accessoryminerals are more frequent in zircon and monazite whichgenerated geochemical anomalies with relatively high con-centrations of REE
Cement of Cosauti sandstones is relatively variedchlorite-hydromicaceous (sometimes with added of kaolin ordikkite) silica or carbonated in which predominated calciteThe thickness of Cosauti Beds varies between 10 and 18meters
Compared with Olchedayev and Lomozov Beds variedby mineralogical and granulometric composition Vendiansection above Cosauti sandstones are relatively homogeneouson all distribution area A certain practical interest wouldpresent the mudstones of Kalyus Beds rich in phosphoriticconcretions
The morphostructure of Olchedayev Lomozov andCosauti beds succession (Vol + Vlm + Vks) in the Dniesterregion are presented quite homogeneous In terms oftectonic the main structural element within the mentionedterritory in this paper are presented by a segment of PodolianFaults Zone oriented in north-western direction and calledby autochthon geologists Dniester Fault (Figure 1) Effusionmagmatism with alkaline lava flows were distinguished thebeginning of a continental riftogenesis which was manifestedin later Proterozoic As a result of geological mapping ithas been shown that the basement along the Dniester Riverhas a narrow linear structure with typical features of riftvalley in which vertical dislocations amplitudes of basementblocks varies within 20ndash60m [2 3 7 10 18] Completed bythe Camenka diabase this structure in sedimentary coverlayers does not reflect practically anything This is observedby comparison of the crystalline basement relief shown inFigure 2 with the surface of lower limit of Vendian Formation(Figure 4) the latter being much smoother The crystallinebasement relief and the surface of lower limit of VendianFormation are observed linear zones oriented in transversaldirections Dniester Fault which occurred in result of thetectonic process much earliermdashin the south-west of pericra-tonic zone of the East European Platform late Archean wasformed a several tectonic faults oriented in preponderantlynorth-eastern direction [10] Perhaps along these faults hadoccurred more intensive erosion processes that had been ledto digging in the Archean relief negative linear forms
In the following way is explained the morphostructuralaspect of the succession beds which are at Vendian basedin the central region of the Dniester River basin Examiningthe summary thickness of Olchedayev Lomozov andCosautiBeds we see a series of relatively isometric areas whichhave comparatively larger thickness which is in correlationwith some earlier faults (Archean) in the region (Figure 4)Accordingly we conclude that the geological research indetection purpose of eventual essential accumulation of REelements should be continued in these areas with relativelylarger thickness of Vendian basal layers
5 Conclusion
(1) As a result of geological mapping in the basal layersof Moldavian Vendian at accessible depths for an eventualexploitation has been located REE mineralization At thesame time the prospect of these layers in the detection pointof view of some industrial accumulations of ores so far nothas been resolved Consequently in the opinion of manyexplorers studying of Vendian rocks needs to be continueduntil getting a univocal solution
(2) In terms of the geological formations of the centralregion of the Dniester river basin the minerals presenteda practical interest in terms of the formation of significant
12 Advances in Geology
0 10 20
(km)
The lower layers of platform cover
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of lower limit of the Vendian formation (m)
Distribution area of Camenka formation
minus160 minus120
minus140
minus80
minus80
minus60
minus40
0
20
30
30
30
40
40
40
40
40
40
40
40
40
50
50
50
50
50
50
50
60
60
60
60
60
80
Olchedayev-Vol Lomozov-Vlm Cosauti-Vks
Isopachites of lower Vendian layers (Vol + Vlm + Vks ) (m)
Figure 4 The lower layers of platform cover Olchedayev (Vol) Lomozov (Vlm) and Cosauti (Vks) Beds in the central region of the DniesterRiver basin [13]
accumulation of RE elements (Sc Y La Ce and Yb) aremonazite (phosphate) and zircon (silicate) probably zirconand monazite are paragenetically associated
(3) In order to locate in the underground space geo-chemical aureoles of the elements mentioned above it isnecessary to study carefully the conditions of migration andconcentration of these elements in diverse mineralogenesprocesses in conditions of the Dniester River basinmdashin theprogressive and retrograde metamorphism ultrametamor-phism metasomatic processes and training processes of thebasal layers of platform cover
(4) Based on the geological and geochemical data accu-mulated in the geological mapping to outline geochemicalaureoles and anomalies which may serve as a direct indexof the presence in crystalline and sedimentary formations ofmechanical aureoles of monazite and (or) zircon
(5) Geological research in detection purpose of eventualessential accumulation of RE elements in central region ofthe Dniester River basin should be continued in relativelylarger thickness of Vendian basal layers the OlchedayevLomozov and Cosauti Beds oriented along the Archean-Proterozoic tectonic faults
(6)The geochemical study of RE elements has remarkableimportance in interpretation and restoration of geological
processes of the geological past Because of this it is importantto investigate concentrations of these elements in differentvarieties of rocks of different ages and origins In particular itis important to establish particular paragenetic types betweenRE elements and other associated minerals to solve thegeological genetically problems
(i) to establish correlative links between particular typesof RE elements and particular types of crystalline orsedimentary rocks
(ii) to determine the origin of rocks which contain theseelements (formed in a single magmatic process in acommon metamorphic facies and in a single sedi-mentogenesis cycle)
If the detection of a deposit of zircon and monazite con-taining rare earths brings a direct practical result geochem-ical study of any region of the earth crust is of high particularimportance in geological prospection Because it solves agreat problem regarding the determination of parageneticassociations of minerals and chemical elements to determinethe type of petrographic provinces specifies geotectonicappearance of territories and to determine the links betweenlithogenic processes and palaeogeographic conditions in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Volume 2014
Mining
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GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Atmospheric SciencesInternational Journal of
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Advances in
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MineralogyInternational Journal of
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Geological ResearchJournal of
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Geology Advances in
Advances in Geology 9
Table2Ve
ndianageb
edsinthec
entralregion
oftheD
niesterR
iver
basin
Serie
sFo
rmations
Theb
eds(localstratigraph
icindices)
microfossilsv
arieties
(thickn
essinmeters)
Thea
verage
concentrations
ofΣRE
(La+
Ce+
Y)lowast
gt
dataarefrom
[7]
Kanilovka
Danilo
vka
Vdn
ShebutintsyB
eds(V
sb)mud
stonesa
ndbrow
nandredd
ish-brownaleurolites
with
sand
stone
intercalationsK
aniloviainsolatia
AJistVend
otaeniaantiq
uaGn
il(17ndash43
m)
54
Pilip
yBe
ds(V
pl)mud
stonesa
ndgreenish
gray
aleurolites
with
sand
stone
intercalations
Vend
otaeniaantiq
uaGn
il(18ndash38
m)
45
Mogilev-Po
dolsk
y
Nagoryany
Vng
Kalyu
sBeds(V
kl)dark
gray
with
brow
nnu
ance
mud
stonesph
osph
oriticc
oncretionscarbo
nate
inclu
sions
with
cone-in
-con
etextureV
endotaeniaantiq
uaGn
ilFu
sosqua
mulaAss
Pilitela
Ass
(55ndash80
m)
58
Dzhurzhevka
Beds
(Vdz)sand
stone
rhythm
icstratifi
catio
nsaleurolitesa
ndmud
stones
Nemiana
simplex
PalVend
otaeniaantiq
uaGn
il(10ndash
25m)
53
Jaryshev
Vjr
Zincov
Beds
(Vzn)mud
stonesrhythmicstratifi
catio
nswith
aleurolitessandstone
intercalations
(15ndash20
m)
60
Bron
nitsaB
eds(V
br)mud
stonesa
ndtuffaceou
sclaystonesgreenstonesw
ithmottledmud
stone
intercalationsB
ronicella
podolicaZa
ica-N
ov(20ndash25m
)64
Bernashe
vkaB
eds(V
brn)sandstonesw
ithmud
stone
intercalationsT
irasia
nadiscifarm
isPa
lEo
holin
iamasquensis
Gnill(5ndash20
m)
67
Mogilev
Vmg
Lyad
ovaB
eds(V
ld)mud
stonesa
ndgreensand
yaleurolitesgreensto
nesredd
ishtuffaceou
scla
ystonesin
theu
pper
levelsmdash
sand
stone
intercalationsLjadova
perjo
rata
Ass(20ndash
25m)
38
Cosau
tiBe
ds(V
ks)sand
stonesw
ithrare
gritstone
intercalations
andaleurolitesN
emiana
simplex
Pal(10ndash
18m)
65
Lomozov
Beds
(Vlm)mud
stonesw
ithaleurolites
andsand
stone
intercalations(0ndash
8m)
94Olcheda
yevB
eds(V
ol)theu
pper
levelsmdash
sand
stone
with
aleurolites
intercalationsthe
lower
levelsmdash
gritstone
with
desand
stone
insm
allsgrains
andmud
stone
intercalations(10ndash35m
)72
Volyn
Camenka
R()
Greenish
gray
aphyric
Diaba
sesw
itham
ygdaleform
impregnatio
nsof
plagiocla
se(1ndash
35m)
Soroca
Bedscon
glom
eratesm
icrocong
lomeratesarkoses
andstones(0ndash
10m)
AR-PR
1Cr
ystalline
basementrocksgneiss
escrystallin
eschistsplagiogranitesplagiomigmatites
enderbitesleucogranitesalaskites
lowast
Incompleted
atao
fspectrographica
nalysisthe
northern
partof
marketterritoryin
theF
igure1
10 Advances in Geology
limits is explained the slow increase of the thickness ofVendian Formation that in immediate nearness of Predo-brogean Depression exceeds 750ndash800 meters In contrastwith lower limit the surface of upper limit of Vendian wassubjected to relatively poor processes of denudation whichchanged the morphostructural aspect appeared after the endof sedimentogenesis processes
As a result of geochemical investigations it was estab-lished that in the lower layers of Vendian Formation theconcentration of RE elements compared with layers of upperlevels is relatively higher (Table 2) In particular it refers toOlchedayev Lomozov and Cosauti Beds of Mogilev Forma-tion For example in the southern part of the territory inOlchedayev Beds was detected an anomalous zone with quitehigh concentrations 119862La = 01 and 119862Ce = 008 [10] whichexceed the geochemical background that is approximately thesame as for Lanthanum and for Cerium
In terms of perspective of detecting some significantconcentrations of RE elements as a result of formationof mechanical aureoles consisting of zircon and mon-azite Olchedayev Lomozov and Cosauti beds represent anobject for much more detailed geological and geochemicalresearches
Olchedayev beds are composed by detrital sedimentaryrocks in big grains (varieties of conglomerates microcon-glomerates and sandstones) and mudstones or sandy mud-stones present in the layerrsquos body in form of relatively shallowintercalations
Geological section of Olchedayev beds is not stablethroughout the whole distribution area but in terms oflithological varieties which form layers and the complexstratifications of this local stratigraphic unit it is observed arelatively constant accordance in the lower levels are presentmicroconglomerates and in the upper onesmdashgritstone inbig grains Specific for Olchedayev layers is the presenceof a layer of clays and sandy clays which separate themicroconglomerates from gritstone
Geological section of Olchedayev beds constructed onbasis of mapping drillings in the southern part of the markedterritory in Figure 1 is presented in the following way
Directly on the altered surface of diabases of CamenkaFormation or on crystalline basement surface crust practi-cally devoid of erosion crust are laid-down
(1) Microconglomerates of brown color with angulargrains of quartz potash feldspar and diabases (up to20ndash25) the color is imposed by clayish cement richin iron hydroxides the thickness of this basal layervaries around 4 meters
(2) Rhythmic intercalations of arkose microconglomer-ates with sandstones in various grain of gray or gray-green color in both lithological varieties are presentinclusions of sandy clay stones and clay stones layerthicknessmdashabout 7 meters
(3) Dark gray microconglomerates with clastic grainsof quartz and potash feldspar microconglomeratecement is clayish and their thickness is 1 meter
(4) Greenish-brown and brown mudstones with thinintercalations of fines sandstone and sandy clay stonethickness 45 meters
(5) Gray and gray-reddish arkose gritstones with isolatedinclusions of quartz and potash feldspar (some grainsreach up to 5 millimeters in diameter) between thesandstones are found rare and thin intercalationsof dark gray mudstones thickness average about 7meters
(6) Gritstones of dark gray color with clayish cementthickness not exceeding 4 meters
(7) Quartz-feldspar gray and light gray sandstones indifferent grain including coarse grains are visiblehorizontal and oblique stratifications of differentgranular fractions sandstone thickness 50 meterson the quartz-feldspar sandstones are laid-down theLomozov Beds
The most common thickness of Olchedayev layers variesaround 25 meters
Sandstones and gritstones of Olchedayev Beds in theupper regions of geological section are of light gray colorIn lower areas depending on potash feldspar quantitiesthe color has reddish hues In microscopic sections areobserved sabulous silitic or mixed structures (sabulous-silitic) cement structure is silitic In terms of compositionthe rocks range from quartzose and arkose varieties Amountof feldspars (potash feldspar prevailed) in most cases doesnot exceed 50 by volume Both in the microconglomerates(also highlighted) and in the sandstones are frequent isolatedgrains of quartzite and rocks of crystalline basement In thelower levels of Olchedayev layers are found frequently smallscales of biotite
The degree of grains rounding from which are formedthe terrigenous rocks varieties of Olchedayev increases withtheir size coarse grains are round and smooth small grainsare ragged Often microconglomerates cement is amorphousmass clayish which together with rock grains imposedporosity quite evident
Accessory minerals in small quantities are presented bygarnet zircon and monazite A minus of geological researchcarried out in the mentioned region in this chapter consistedin that a mineralogical analysis which would determine thequantitative relations between zircon and monazite was notachieved As we have remarked the origin of mineralizationrich in RE elements in geological formations from the Dni-ester basin region is a great problem Additional informationwhich would facilitate the solving of this problem wouldpresent the thorough study of the separate grains of zirconandmonazite from the structure and composition andwouldbe extremely important in terms of geochronology It ispossible that the absolute ages of zircon and monazite shouldcoincide with the ages of these minerals found in crystallineformations of basement It did not exclude the case that theseminerals are different as assortment of isomorphic elementsin their chemical composition Such research are importantfor solving of various fundamental and practical geologicalproblems which can determine the origin of zircon and
Advances in Geology 11
monazite the sedimentogenes processes and the formationof mechanical aureoles with significant concentrations ofuseful components Unfortunately because of changes thathave intervened in the last decade of the past century in theRepublic of Moldova all expensive geological research wassuspended
In the Olchedayev rocks are found rare impregnationsof galena barite fluorite and xenotime (YPO
4) Because
monazite and zircon are contained isomorphic impurities ofTh and U and xenotimemdashabout 5 UO
2mdashOlchedayev Beds
are characterized by a relatively high radioactivity whichrarely reaches up to 500 and 780 micronshour
Lomozov beds are formed preponderant frommudstonesa dark gray color with mica they are intercalations ofsandstones finely dispersed The layers thickness has notbeen exceeding 5 meters In some places Lomozov rocks aremissing At level of Lomozov Beds is identified a complexlayer composed of very fine stratifications of fine-grainedsandstone and of dark gray mudstones relatively rich inminerals containingRE Because the average concentration ofLa + Ce + Y amount compared to other Vendian stratifica-tions is the largestmdash94 gt (Table 2)
The mudstones consisted of an amorphous mass ofgray color and in microscopic sections brown color withabundant additions of small scales of hydromica disposedparallel with surfaces of sedimentation On the fund of thisbasedmass are detected small granules (silitic) of quartz withangular forms In Lomozov Beds have a specific character inthe mudstones composition are often presented inclusions ofbiotite and more rarely of muscovite as elongated scales
Cosauti Beds in lithological point of view of this localstratigraphic unit are relatively homogeneous and are com-posed almost solely of sandstone Dark mudstone interca-lations and dispersed fine sandstone are marked only inpatches Cosauti sandstones have white color with sugaraspect in a homogeneous medium or small grain
In microscopic sections sandstones are psammitic clearstructure Aleurite fraction (01 millimeters) is about 5by rock volume (rarelymdash10ndash12) Large grains of quartzare frequent (about 2 millimeters) embedded in argillite-sandy mass (a few tenths of a percent) but in granulometricpoint of view sandstone are very well sorted In the Cosautibeds were discovered sandstone consist not only of quartzgrains Quartzose varieties usually contain about 10 ofdetrital material consisting of other minerals The quartz-feldspar and arkose sandstones are predominated in whichthe feldspar grains scant of above 20 (potassium feldsparis prevailing) It is common inclusions of biotite in the formof scales about 1-2 from volume Less commonly in therock small granules of quartzite are found In small isolatedgranules can be identified pyrite and magnetite Accessoryminerals are more frequent in zircon and monazite whichgenerated geochemical anomalies with relatively high con-centrations of REE
Cement of Cosauti sandstones is relatively variedchlorite-hydromicaceous (sometimes with added of kaolin ordikkite) silica or carbonated in which predominated calciteThe thickness of Cosauti Beds varies between 10 and 18meters
Compared with Olchedayev and Lomozov Beds variedby mineralogical and granulometric composition Vendiansection above Cosauti sandstones are relatively homogeneouson all distribution area A certain practical interest wouldpresent the mudstones of Kalyus Beds rich in phosphoriticconcretions
The morphostructure of Olchedayev Lomozov andCosauti beds succession (Vol + Vlm + Vks) in the Dniesterregion are presented quite homogeneous In terms oftectonic the main structural element within the mentionedterritory in this paper are presented by a segment of PodolianFaults Zone oriented in north-western direction and calledby autochthon geologists Dniester Fault (Figure 1) Effusionmagmatism with alkaline lava flows were distinguished thebeginning of a continental riftogenesis which was manifestedin later Proterozoic As a result of geological mapping ithas been shown that the basement along the Dniester Riverhas a narrow linear structure with typical features of riftvalley in which vertical dislocations amplitudes of basementblocks varies within 20ndash60m [2 3 7 10 18] Completed bythe Camenka diabase this structure in sedimentary coverlayers does not reflect practically anything This is observedby comparison of the crystalline basement relief shown inFigure 2 with the surface of lower limit of Vendian Formation(Figure 4) the latter being much smoother The crystallinebasement relief and the surface of lower limit of VendianFormation are observed linear zones oriented in transversaldirections Dniester Fault which occurred in result of thetectonic process much earliermdashin the south-west of pericra-tonic zone of the East European Platform late Archean wasformed a several tectonic faults oriented in preponderantlynorth-eastern direction [10] Perhaps along these faults hadoccurred more intensive erosion processes that had been ledto digging in the Archean relief negative linear forms
In the following way is explained the morphostructuralaspect of the succession beds which are at Vendian basedin the central region of the Dniester River basin Examiningthe summary thickness of Olchedayev Lomozov andCosautiBeds we see a series of relatively isometric areas whichhave comparatively larger thickness which is in correlationwith some earlier faults (Archean) in the region (Figure 4)Accordingly we conclude that the geological research indetection purpose of eventual essential accumulation of REelements should be continued in these areas with relativelylarger thickness of Vendian basal layers
5 Conclusion
(1) As a result of geological mapping in the basal layersof Moldavian Vendian at accessible depths for an eventualexploitation has been located REE mineralization At thesame time the prospect of these layers in the detection pointof view of some industrial accumulations of ores so far nothas been resolved Consequently in the opinion of manyexplorers studying of Vendian rocks needs to be continueduntil getting a univocal solution
(2) In terms of the geological formations of the centralregion of the Dniester river basin the minerals presenteda practical interest in terms of the formation of significant
12 Advances in Geology
0 10 20
(km)
The lower layers of platform cover
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of lower limit of the Vendian formation (m)
Distribution area of Camenka formation
minus160 minus120
minus140
minus80
minus80
minus60
minus40
0
20
30
30
30
40
40
40
40
40
40
40
40
40
50
50
50
50
50
50
50
60
60
60
60
60
80
Olchedayev-Vol Lomozov-Vlm Cosauti-Vks
Isopachites of lower Vendian layers (Vol + Vlm + Vks ) (m)
Figure 4 The lower layers of platform cover Olchedayev (Vol) Lomozov (Vlm) and Cosauti (Vks) Beds in the central region of the DniesterRiver basin [13]
accumulation of RE elements (Sc Y La Ce and Yb) aremonazite (phosphate) and zircon (silicate) probably zirconand monazite are paragenetically associated
(3) In order to locate in the underground space geo-chemical aureoles of the elements mentioned above it isnecessary to study carefully the conditions of migration andconcentration of these elements in diverse mineralogenesprocesses in conditions of the Dniester River basinmdashin theprogressive and retrograde metamorphism ultrametamor-phism metasomatic processes and training processes of thebasal layers of platform cover
(4) Based on the geological and geochemical data accu-mulated in the geological mapping to outline geochemicalaureoles and anomalies which may serve as a direct indexof the presence in crystalline and sedimentary formations ofmechanical aureoles of monazite and (or) zircon
(5) Geological research in detection purpose of eventualessential accumulation of RE elements in central region ofthe Dniester River basin should be continued in relativelylarger thickness of Vendian basal layers the OlchedayevLomozov and Cosauti Beds oriented along the Archean-Proterozoic tectonic faults
(6)The geochemical study of RE elements has remarkableimportance in interpretation and restoration of geological
processes of the geological past Because of this it is importantto investigate concentrations of these elements in differentvarieties of rocks of different ages and origins In particular itis important to establish particular paragenetic types betweenRE elements and other associated minerals to solve thegeological genetically problems
(i) to establish correlative links between particular typesof RE elements and particular types of crystalline orsedimentary rocks
(ii) to determine the origin of rocks which contain theseelements (formed in a single magmatic process in acommon metamorphic facies and in a single sedi-mentogenesis cycle)
If the detection of a deposit of zircon and monazite con-taining rare earths brings a direct practical result geochem-ical study of any region of the earth crust is of high particularimportance in geological prospection Because it solves agreat problem regarding the determination of parageneticassociations of minerals and chemical elements to determinethe type of petrographic provinces specifies geotectonicappearance of territories and to determine the links betweenlithogenic processes and palaeogeographic conditions in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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MineralogyInternational Journal of
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Geology Advances in
10 Advances in Geology
limits is explained the slow increase of the thickness ofVendian Formation that in immediate nearness of Predo-brogean Depression exceeds 750ndash800 meters In contrastwith lower limit the surface of upper limit of Vendian wassubjected to relatively poor processes of denudation whichchanged the morphostructural aspect appeared after the endof sedimentogenesis processes
As a result of geochemical investigations it was estab-lished that in the lower layers of Vendian Formation theconcentration of RE elements compared with layers of upperlevels is relatively higher (Table 2) In particular it refers toOlchedayev Lomozov and Cosauti Beds of Mogilev Forma-tion For example in the southern part of the territory inOlchedayev Beds was detected an anomalous zone with quitehigh concentrations 119862La = 01 and 119862Ce = 008 [10] whichexceed the geochemical background that is approximately thesame as for Lanthanum and for Cerium
In terms of perspective of detecting some significantconcentrations of RE elements as a result of formationof mechanical aureoles consisting of zircon and mon-azite Olchedayev Lomozov and Cosauti beds represent anobject for much more detailed geological and geochemicalresearches
Olchedayev beds are composed by detrital sedimentaryrocks in big grains (varieties of conglomerates microcon-glomerates and sandstones) and mudstones or sandy mud-stones present in the layerrsquos body in form of relatively shallowintercalations
Geological section of Olchedayev beds is not stablethroughout the whole distribution area but in terms oflithological varieties which form layers and the complexstratifications of this local stratigraphic unit it is observed arelatively constant accordance in the lower levels are presentmicroconglomerates and in the upper onesmdashgritstone inbig grains Specific for Olchedayev layers is the presenceof a layer of clays and sandy clays which separate themicroconglomerates from gritstone
Geological section of Olchedayev beds constructed onbasis of mapping drillings in the southern part of the markedterritory in Figure 1 is presented in the following way
Directly on the altered surface of diabases of CamenkaFormation or on crystalline basement surface crust practi-cally devoid of erosion crust are laid-down
(1) Microconglomerates of brown color with angulargrains of quartz potash feldspar and diabases (up to20ndash25) the color is imposed by clayish cement richin iron hydroxides the thickness of this basal layervaries around 4 meters
(2) Rhythmic intercalations of arkose microconglomer-ates with sandstones in various grain of gray or gray-green color in both lithological varieties are presentinclusions of sandy clay stones and clay stones layerthicknessmdashabout 7 meters
(3) Dark gray microconglomerates with clastic grainsof quartz and potash feldspar microconglomeratecement is clayish and their thickness is 1 meter
(4) Greenish-brown and brown mudstones with thinintercalations of fines sandstone and sandy clay stonethickness 45 meters
(5) Gray and gray-reddish arkose gritstones with isolatedinclusions of quartz and potash feldspar (some grainsreach up to 5 millimeters in diameter) between thesandstones are found rare and thin intercalationsof dark gray mudstones thickness average about 7meters
(6) Gritstones of dark gray color with clayish cementthickness not exceeding 4 meters
(7) Quartz-feldspar gray and light gray sandstones indifferent grain including coarse grains are visiblehorizontal and oblique stratifications of differentgranular fractions sandstone thickness 50 meterson the quartz-feldspar sandstones are laid-down theLomozov Beds
The most common thickness of Olchedayev layers variesaround 25 meters
Sandstones and gritstones of Olchedayev Beds in theupper regions of geological section are of light gray colorIn lower areas depending on potash feldspar quantitiesthe color has reddish hues In microscopic sections areobserved sabulous silitic or mixed structures (sabulous-silitic) cement structure is silitic In terms of compositionthe rocks range from quartzose and arkose varieties Amountof feldspars (potash feldspar prevailed) in most cases doesnot exceed 50 by volume Both in the microconglomerates(also highlighted) and in the sandstones are frequent isolatedgrains of quartzite and rocks of crystalline basement In thelower levels of Olchedayev layers are found frequently smallscales of biotite
The degree of grains rounding from which are formedthe terrigenous rocks varieties of Olchedayev increases withtheir size coarse grains are round and smooth small grainsare ragged Often microconglomerates cement is amorphousmass clayish which together with rock grains imposedporosity quite evident
Accessory minerals in small quantities are presented bygarnet zircon and monazite A minus of geological researchcarried out in the mentioned region in this chapter consistedin that a mineralogical analysis which would determine thequantitative relations between zircon and monazite was notachieved As we have remarked the origin of mineralizationrich in RE elements in geological formations from the Dni-ester basin region is a great problem Additional informationwhich would facilitate the solving of this problem wouldpresent the thorough study of the separate grains of zirconandmonazite from the structure and composition andwouldbe extremely important in terms of geochronology It ispossible that the absolute ages of zircon and monazite shouldcoincide with the ages of these minerals found in crystallineformations of basement It did not exclude the case that theseminerals are different as assortment of isomorphic elementsin their chemical composition Such research are importantfor solving of various fundamental and practical geologicalproblems which can determine the origin of zircon and
Advances in Geology 11
monazite the sedimentogenes processes and the formationof mechanical aureoles with significant concentrations ofuseful components Unfortunately because of changes thathave intervened in the last decade of the past century in theRepublic of Moldova all expensive geological research wassuspended
In the Olchedayev rocks are found rare impregnationsof galena barite fluorite and xenotime (YPO
4) Because
monazite and zircon are contained isomorphic impurities ofTh and U and xenotimemdashabout 5 UO
2mdashOlchedayev Beds
are characterized by a relatively high radioactivity whichrarely reaches up to 500 and 780 micronshour
Lomozov beds are formed preponderant frommudstonesa dark gray color with mica they are intercalations ofsandstones finely dispersed The layers thickness has notbeen exceeding 5 meters In some places Lomozov rocks aremissing At level of Lomozov Beds is identified a complexlayer composed of very fine stratifications of fine-grainedsandstone and of dark gray mudstones relatively rich inminerals containingRE Because the average concentration ofLa + Ce + Y amount compared to other Vendian stratifica-tions is the largestmdash94 gt (Table 2)
The mudstones consisted of an amorphous mass ofgray color and in microscopic sections brown color withabundant additions of small scales of hydromica disposedparallel with surfaces of sedimentation On the fund of thisbasedmass are detected small granules (silitic) of quartz withangular forms In Lomozov Beds have a specific character inthe mudstones composition are often presented inclusions ofbiotite and more rarely of muscovite as elongated scales
Cosauti Beds in lithological point of view of this localstratigraphic unit are relatively homogeneous and are com-posed almost solely of sandstone Dark mudstone interca-lations and dispersed fine sandstone are marked only inpatches Cosauti sandstones have white color with sugaraspect in a homogeneous medium or small grain
In microscopic sections sandstones are psammitic clearstructure Aleurite fraction (01 millimeters) is about 5by rock volume (rarelymdash10ndash12) Large grains of quartzare frequent (about 2 millimeters) embedded in argillite-sandy mass (a few tenths of a percent) but in granulometricpoint of view sandstone are very well sorted In the Cosautibeds were discovered sandstone consist not only of quartzgrains Quartzose varieties usually contain about 10 ofdetrital material consisting of other minerals The quartz-feldspar and arkose sandstones are predominated in whichthe feldspar grains scant of above 20 (potassium feldsparis prevailing) It is common inclusions of biotite in the formof scales about 1-2 from volume Less commonly in therock small granules of quartzite are found In small isolatedgranules can be identified pyrite and magnetite Accessoryminerals are more frequent in zircon and monazite whichgenerated geochemical anomalies with relatively high con-centrations of REE
Cement of Cosauti sandstones is relatively variedchlorite-hydromicaceous (sometimes with added of kaolin ordikkite) silica or carbonated in which predominated calciteThe thickness of Cosauti Beds varies between 10 and 18meters
Compared with Olchedayev and Lomozov Beds variedby mineralogical and granulometric composition Vendiansection above Cosauti sandstones are relatively homogeneouson all distribution area A certain practical interest wouldpresent the mudstones of Kalyus Beds rich in phosphoriticconcretions
The morphostructure of Olchedayev Lomozov andCosauti beds succession (Vol + Vlm + Vks) in the Dniesterregion are presented quite homogeneous In terms oftectonic the main structural element within the mentionedterritory in this paper are presented by a segment of PodolianFaults Zone oriented in north-western direction and calledby autochthon geologists Dniester Fault (Figure 1) Effusionmagmatism with alkaline lava flows were distinguished thebeginning of a continental riftogenesis which was manifestedin later Proterozoic As a result of geological mapping ithas been shown that the basement along the Dniester Riverhas a narrow linear structure with typical features of riftvalley in which vertical dislocations amplitudes of basementblocks varies within 20ndash60m [2 3 7 10 18] Completed bythe Camenka diabase this structure in sedimentary coverlayers does not reflect practically anything This is observedby comparison of the crystalline basement relief shown inFigure 2 with the surface of lower limit of Vendian Formation(Figure 4) the latter being much smoother The crystallinebasement relief and the surface of lower limit of VendianFormation are observed linear zones oriented in transversaldirections Dniester Fault which occurred in result of thetectonic process much earliermdashin the south-west of pericra-tonic zone of the East European Platform late Archean wasformed a several tectonic faults oriented in preponderantlynorth-eastern direction [10] Perhaps along these faults hadoccurred more intensive erosion processes that had been ledto digging in the Archean relief negative linear forms
In the following way is explained the morphostructuralaspect of the succession beds which are at Vendian basedin the central region of the Dniester River basin Examiningthe summary thickness of Olchedayev Lomozov andCosautiBeds we see a series of relatively isometric areas whichhave comparatively larger thickness which is in correlationwith some earlier faults (Archean) in the region (Figure 4)Accordingly we conclude that the geological research indetection purpose of eventual essential accumulation of REelements should be continued in these areas with relativelylarger thickness of Vendian basal layers
5 Conclusion
(1) As a result of geological mapping in the basal layersof Moldavian Vendian at accessible depths for an eventualexploitation has been located REE mineralization At thesame time the prospect of these layers in the detection pointof view of some industrial accumulations of ores so far nothas been resolved Consequently in the opinion of manyexplorers studying of Vendian rocks needs to be continueduntil getting a univocal solution
(2) In terms of the geological formations of the centralregion of the Dniester river basin the minerals presenteda practical interest in terms of the formation of significant
12 Advances in Geology
0 10 20
(km)
The lower layers of platform cover
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of lower limit of the Vendian formation (m)
Distribution area of Camenka formation
minus160 minus120
minus140
minus80
minus80
minus60
minus40
0
20
30
30
30
40
40
40
40
40
40
40
40
40
50
50
50
50
50
50
50
60
60
60
60
60
80
Olchedayev-Vol Lomozov-Vlm Cosauti-Vks
Isopachites of lower Vendian layers (Vol + Vlm + Vks ) (m)
Figure 4 The lower layers of platform cover Olchedayev (Vol) Lomozov (Vlm) and Cosauti (Vks) Beds in the central region of the DniesterRiver basin [13]
accumulation of RE elements (Sc Y La Ce and Yb) aremonazite (phosphate) and zircon (silicate) probably zirconand monazite are paragenetically associated
(3) In order to locate in the underground space geo-chemical aureoles of the elements mentioned above it isnecessary to study carefully the conditions of migration andconcentration of these elements in diverse mineralogenesprocesses in conditions of the Dniester River basinmdashin theprogressive and retrograde metamorphism ultrametamor-phism metasomatic processes and training processes of thebasal layers of platform cover
(4) Based on the geological and geochemical data accu-mulated in the geological mapping to outline geochemicalaureoles and anomalies which may serve as a direct indexof the presence in crystalline and sedimentary formations ofmechanical aureoles of monazite and (or) zircon
(5) Geological research in detection purpose of eventualessential accumulation of RE elements in central region ofthe Dniester River basin should be continued in relativelylarger thickness of Vendian basal layers the OlchedayevLomozov and Cosauti Beds oriented along the Archean-Proterozoic tectonic faults
(6)The geochemical study of RE elements has remarkableimportance in interpretation and restoration of geological
processes of the geological past Because of this it is importantto investigate concentrations of these elements in differentvarieties of rocks of different ages and origins In particular itis important to establish particular paragenetic types betweenRE elements and other associated minerals to solve thegeological genetically problems
(i) to establish correlative links between particular typesof RE elements and particular types of crystalline orsedimentary rocks
(ii) to determine the origin of rocks which contain theseelements (formed in a single magmatic process in acommon metamorphic facies and in a single sedi-mentogenesis cycle)
If the detection of a deposit of zircon and monazite con-taining rare earths brings a direct practical result geochem-ical study of any region of the earth crust is of high particularimportance in geological prospection Because it solves agreat problem regarding the determination of parageneticassociations of minerals and chemical elements to determinethe type of petrographic provinces specifies geotectonicappearance of territories and to determine the links betweenlithogenic processes and palaeogeographic conditions in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ClimatologyJournal of
EcologyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EarthquakesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom
Applied ampEnvironmentalSoil Science
Volume 2014
Mining
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal of
Geophysics
OceanographyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Atmospheric SciencesInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
OceanographyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MineralogyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MeteorologyAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Paleontology JournalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Geological ResearchJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Geology Advances in
Advances in Geology 11
monazite the sedimentogenes processes and the formationof mechanical aureoles with significant concentrations ofuseful components Unfortunately because of changes thathave intervened in the last decade of the past century in theRepublic of Moldova all expensive geological research wassuspended
In the Olchedayev rocks are found rare impregnationsof galena barite fluorite and xenotime (YPO
4) Because
monazite and zircon are contained isomorphic impurities ofTh and U and xenotimemdashabout 5 UO
2mdashOlchedayev Beds
are characterized by a relatively high radioactivity whichrarely reaches up to 500 and 780 micronshour
Lomozov beds are formed preponderant frommudstonesa dark gray color with mica they are intercalations ofsandstones finely dispersed The layers thickness has notbeen exceeding 5 meters In some places Lomozov rocks aremissing At level of Lomozov Beds is identified a complexlayer composed of very fine stratifications of fine-grainedsandstone and of dark gray mudstones relatively rich inminerals containingRE Because the average concentration ofLa + Ce + Y amount compared to other Vendian stratifica-tions is the largestmdash94 gt (Table 2)
The mudstones consisted of an amorphous mass ofgray color and in microscopic sections brown color withabundant additions of small scales of hydromica disposedparallel with surfaces of sedimentation On the fund of thisbasedmass are detected small granules (silitic) of quartz withangular forms In Lomozov Beds have a specific character inthe mudstones composition are often presented inclusions ofbiotite and more rarely of muscovite as elongated scales
Cosauti Beds in lithological point of view of this localstratigraphic unit are relatively homogeneous and are com-posed almost solely of sandstone Dark mudstone interca-lations and dispersed fine sandstone are marked only inpatches Cosauti sandstones have white color with sugaraspect in a homogeneous medium or small grain
In microscopic sections sandstones are psammitic clearstructure Aleurite fraction (01 millimeters) is about 5by rock volume (rarelymdash10ndash12) Large grains of quartzare frequent (about 2 millimeters) embedded in argillite-sandy mass (a few tenths of a percent) but in granulometricpoint of view sandstone are very well sorted In the Cosautibeds were discovered sandstone consist not only of quartzgrains Quartzose varieties usually contain about 10 ofdetrital material consisting of other minerals The quartz-feldspar and arkose sandstones are predominated in whichthe feldspar grains scant of above 20 (potassium feldsparis prevailing) It is common inclusions of biotite in the formof scales about 1-2 from volume Less commonly in therock small granules of quartzite are found In small isolatedgranules can be identified pyrite and magnetite Accessoryminerals are more frequent in zircon and monazite whichgenerated geochemical anomalies with relatively high con-centrations of REE
Cement of Cosauti sandstones is relatively variedchlorite-hydromicaceous (sometimes with added of kaolin ordikkite) silica or carbonated in which predominated calciteThe thickness of Cosauti Beds varies between 10 and 18meters
Compared with Olchedayev and Lomozov Beds variedby mineralogical and granulometric composition Vendiansection above Cosauti sandstones are relatively homogeneouson all distribution area A certain practical interest wouldpresent the mudstones of Kalyus Beds rich in phosphoriticconcretions
The morphostructure of Olchedayev Lomozov andCosauti beds succession (Vol + Vlm + Vks) in the Dniesterregion are presented quite homogeneous In terms oftectonic the main structural element within the mentionedterritory in this paper are presented by a segment of PodolianFaults Zone oriented in north-western direction and calledby autochthon geologists Dniester Fault (Figure 1) Effusionmagmatism with alkaline lava flows were distinguished thebeginning of a continental riftogenesis which was manifestedin later Proterozoic As a result of geological mapping ithas been shown that the basement along the Dniester Riverhas a narrow linear structure with typical features of riftvalley in which vertical dislocations amplitudes of basementblocks varies within 20ndash60m [2 3 7 10 18] Completed bythe Camenka diabase this structure in sedimentary coverlayers does not reflect practically anything This is observedby comparison of the crystalline basement relief shown inFigure 2 with the surface of lower limit of Vendian Formation(Figure 4) the latter being much smoother The crystallinebasement relief and the surface of lower limit of VendianFormation are observed linear zones oriented in transversaldirections Dniester Fault which occurred in result of thetectonic process much earliermdashin the south-west of pericra-tonic zone of the East European Platform late Archean wasformed a several tectonic faults oriented in preponderantlynorth-eastern direction [10] Perhaps along these faults hadoccurred more intensive erosion processes that had been ledto digging in the Archean relief negative linear forms
In the following way is explained the morphostructuralaspect of the succession beds which are at Vendian basedin the central region of the Dniester River basin Examiningthe summary thickness of Olchedayev Lomozov andCosautiBeds we see a series of relatively isometric areas whichhave comparatively larger thickness which is in correlationwith some earlier faults (Archean) in the region (Figure 4)Accordingly we conclude that the geological research indetection purpose of eventual essential accumulation of REelements should be continued in these areas with relativelylarger thickness of Vendian basal layers
5 Conclusion
(1) As a result of geological mapping in the basal layersof Moldavian Vendian at accessible depths for an eventualexploitation has been located REE mineralization At thesame time the prospect of these layers in the detection pointof view of some industrial accumulations of ores so far nothas been resolved Consequently in the opinion of manyexplorers studying of Vendian rocks needs to be continueduntil getting a univocal solution
(2) In terms of the geological formations of the centralregion of the Dniester river basin the minerals presenteda practical interest in terms of the formation of significant
12 Advances in Geology
0 10 20
(km)
The lower layers of platform cover
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of lower limit of the Vendian formation (m)
Distribution area of Camenka formation
minus160 minus120
minus140
minus80
minus80
minus60
minus40
0
20
30
30
30
40
40
40
40
40
40
40
40
40
50
50
50
50
50
50
50
60
60
60
60
60
80
Olchedayev-Vol Lomozov-Vlm Cosauti-Vks
Isopachites of lower Vendian layers (Vol + Vlm + Vks ) (m)
Figure 4 The lower layers of platform cover Olchedayev (Vol) Lomozov (Vlm) and Cosauti (Vks) Beds in the central region of the DniesterRiver basin [13]
accumulation of RE elements (Sc Y La Ce and Yb) aremonazite (phosphate) and zircon (silicate) probably zirconand monazite are paragenetically associated
(3) In order to locate in the underground space geo-chemical aureoles of the elements mentioned above it isnecessary to study carefully the conditions of migration andconcentration of these elements in diverse mineralogenesprocesses in conditions of the Dniester River basinmdashin theprogressive and retrograde metamorphism ultrametamor-phism metasomatic processes and training processes of thebasal layers of platform cover
(4) Based on the geological and geochemical data accu-mulated in the geological mapping to outline geochemicalaureoles and anomalies which may serve as a direct indexof the presence in crystalline and sedimentary formations ofmechanical aureoles of monazite and (or) zircon
(5) Geological research in detection purpose of eventualessential accumulation of RE elements in central region ofthe Dniester River basin should be continued in relativelylarger thickness of Vendian basal layers the OlchedayevLomozov and Cosauti Beds oriented along the Archean-Proterozoic tectonic faults
(6)The geochemical study of RE elements has remarkableimportance in interpretation and restoration of geological
processes of the geological past Because of this it is importantto investigate concentrations of these elements in differentvarieties of rocks of different ages and origins In particular itis important to establish particular paragenetic types betweenRE elements and other associated minerals to solve thegeological genetically problems
(i) to establish correlative links between particular typesof RE elements and particular types of crystalline orsedimentary rocks
(ii) to determine the origin of rocks which contain theseelements (formed in a single magmatic process in acommon metamorphic facies and in a single sedi-mentogenesis cycle)
If the detection of a deposit of zircon and monazite con-taining rare earths brings a direct practical result geochem-ical study of any region of the earth crust is of high particularimportance in geological prospection Because it solves agreat problem regarding the determination of parageneticassociations of minerals and chemical elements to determinethe type of petrographic provinces specifies geotectonicappearance of territories and to determine the links betweenlithogenic processes and palaeogeographic conditions in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ClimatologyJournal of
EcologyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EarthquakesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom
Applied ampEnvironmentalSoil Science
Volume 2014
Mining
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal of
Geophysics
OceanographyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Atmospheric SciencesInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
OceanographyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MineralogyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MeteorologyAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Paleontology JournalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Geological ResearchJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Geology Advances in
12 Advances in Geology
0 10 20
(km)
The lower layers of platform cover
Central region of the Dniester river basin
The segment Naslavcea-Iarova-Camenka-Rezina
Isohypses of lower limit of the Vendian formation (m)
Distribution area of Camenka formation
minus160 minus120
minus140
minus80
minus80
minus60
minus40
0
20
30
30
30
40
40
40
40
40
40
40
40
40
50
50
50
50
50
50
50
60
60
60
60
60
80
Olchedayev-Vol Lomozov-Vlm Cosauti-Vks
Isopachites of lower Vendian layers (Vol + Vlm + Vks ) (m)
Figure 4 The lower layers of platform cover Olchedayev (Vol) Lomozov (Vlm) and Cosauti (Vks) Beds in the central region of the DniesterRiver basin [13]
accumulation of RE elements (Sc Y La Ce and Yb) aremonazite (phosphate) and zircon (silicate) probably zirconand monazite are paragenetically associated
(3) In order to locate in the underground space geo-chemical aureoles of the elements mentioned above it isnecessary to study carefully the conditions of migration andconcentration of these elements in diverse mineralogenesprocesses in conditions of the Dniester River basinmdashin theprogressive and retrograde metamorphism ultrametamor-phism metasomatic processes and training processes of thebasal layers of platform cover
(4) Based on the geological and geochemical data accu-mulated in the geological mapping to outline geochemicalaureoles and anomalies which may serve as a direct indexof the presence in crystalline and sedimentary formations ofmechanical aureoles of monazite and (or) zircon
(5) Geological research in detection purpose of eventualessential accumulation of RE elements in central region ofthe Dniester River basin should be continued in relativelylarger thickness of Vendian basal layers the OlchedayevLomozov and Cosauti Beds oriented along the Archean-Proterozoic tectonic faults
(6)The geochemical study of RE elements has remarkableimportance in interpretation and restoration of geological
processes of the geological past Because of this it is importantto investigate concentrations of these elements in differentvarieties of rocks of different ages and origins In particular itis important to establish particular paragenetic types betweenRE elements and other associated minerals to solve thegeological genetically problems
(i) to establish correlative links between particular typesof RE elements and particular types of crystalline orsedimentary rocks
(ii) to determine the origin of rocks which contain theseelements (formed in a single magmatic process in acommon metamorphic facies and in a single sedi-mentogenesis cycle)
If the detection of a deposit of zircon and monazite con-taining rare earths brings a direct practical result geochem-ical study of any region of the earth crust is of high particularimportance in geological prospection Because it solves agreat problem regarding the determination of parageneticassociations of minerals and chemical elements to determinethe type of petrographic provinces specifies geotectonicappearance of territories and to determine the links betweenlithogenic processes and palaeogeographic conditions in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ClimatologyJournal of
EcologyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EarthquakesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom
Applied ampEnvironmentalSoil Science
Volume 2014
Mining
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal of
Geophysics
OceanographyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Atmospheric SciencesInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
OceanographyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MineralogyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MeteorologyAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Paleontology JournalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Geological ResearchJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Geology Advances in
Advances in Geology 13
the zone to resolve stratigraphic issues Obviously all thisgeological data are served primarily for resolving appliedgeological problems such as detection of other types of usefulmineral deposits
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper
References
[1] Geology of the USSRMoldavian SSR vol 45 Nedra MoscowRussia 1969
[2] V I Dimo The Geological Report on the Results of DeepGeological Formations Study Effectuated in 1965ndash1971 Years inthe Northern Region of Moldavian Dniester River Basin AGRMFunds Chisinau Moldova 1971
[3] I T Ceban The Geological Report on the Results of Deep Geo-logical Formations Study to Indentify Metallogenetic PerspectivesStructures of the Dniester Fault Zone AGRM Funds ChisinauMoldova 1981 (Russian)
[4] P D Bucatciuc The Geological Report on the SedimentaryCover Formations of Upper Precambrian in the South-WesternPericratonic Region of the East European Platform AGRMfunds Chisinau Moldova 1973 (Russian)
[5] V Ciobotaru ldquoGeneral considerations on the Dniester-Prutinterfluves geology especially of the north-eastern region ofRepublic of Moldovardquo in Scientific Annals of Moldova StateUniversity Series Chemical-Biological Sciences pp 169ndash174CEP USM Chisinau Moldova 2004
[6] D LvinaTheGeological Report on the Distribution Particularityof the Non-Ferrous Rare and Rare Earth Elements in Pre-cambrian Formations from the North Moldova AGRM FundsChisinau Moldova 1972 (Russian)
[7] A Zaharov Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Ocnita)The Geological Report on the General Geological Mapping at150000 Scales Made the Topographic Planes M-35-127-D M-35-128-C D-b M-35-140-A D and Finishing the Study GeologicalProspecting in General Scale 150000 from Topographic Plan M-35-140-D AGRM Funds Chisinau Moldova 1992 (Russian)
[8] A V Drumea ldquoMoldovardquo in Encyclopedia of European andAsian Regional Geology F M Moores and R W FairbridgeEds Encyclopedia of Earth Sciences Series pp 537ndash540Chapman amp Hall London UK 1997
[9] A V Drumea and V I Canicovski Tectonic Moldavian SSRAcademy of USSR Moscow Russia 1961 (Russian)
[10] G H Dmitrov Charnockites Formation of Central Region of theBug River Basin IGFM Kiev 1977 (Russian)
[11] A Zaharov C Sergheev and V Ciobotaru The GeologicalReport on the Geological Structure and Useful Mineral Depositsin Mining-Industrial Region Rezina AGRM Funds ChisinauMoldova 1987 (Russian)
[12] A Popuiac ldquoGeneral geochemistry of rare earths in the centralregion of theDniester river basin Republic ofMoldovardquo Journalof Rare Earths vol 28 supplement 1 pp 513ndash516 2010
[13] A Popuiac ldquoThe detection premises of useful mineral depositsin the Vendian formations in the central region of Dniesterriver basinrdquo Scientific Notes of Taurida V Vernadsky NationalUniversity Series Geography vol 24 no 63 pp 98ndash105 2011
[14] V E Hain and N A Bojko Geotectonic History PrecambrianNedra Moscow Russia 1984 (Russian)
[15] S S Cruglov and A K Tapko Tectonic of Ukraine NedraMoscow Russia 1988 (Russian)
[16] L N Kogarko ldquoAlkaline magmatism in the Earths historyrdquo inThe Planet Earth The Encyclopedic Reference Book pp 76ndash81VSEGEI St Petersburg Russia 2004
[17] V V Scerbina Geochemical Peculiarities and Deposit Types ofScandium Gosgheoltehizdat Moscow Russia 1960 (Russian)
[18] V Ryborak Geological Structure and Useful Mineral Depositsin the Central Region of the Dniester River Basin (Soroca) TheGeological Report on the General Geological Mapping at 150000ScalesMade the Topographic PlanesM-35-141-CM-35-142- CDD and Finishing the StudyGeological Prospecting inGeneral Scale150000 from Topographic Plan M-35-141-A AGRM FundsChisinau Moldova 1990 (Russian)
[19] V A Velicanov Ed The Vendian of Podolia Excursion Guidefor III International Symposium on Cambrian System andVendianCambrian Boundary Kiev Ukraine 1990
[20] V A Velicanov E A Aseeva and M A Fedonkin Vendian ofUkraine Naukova dumka Kiev 1986 (Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ClimatologyJournal of
EcologyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EarthquakesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom
Applied ampEnvironmentalSoil Science
Volume 2014
Mining
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Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
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OceanographyInternational Journal of
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ClimatologyJournal of
EcologyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EarthquakesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom
Applied ampEnvironmentalSoil Science
Volume 2014
Mining
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal of
Geophysics
OceanographyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Atmospheric SciencesInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
OceanographyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MineralogyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MeteorologyAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Paleontology JournalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Geological ResearchJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Geology Advances in