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II CHAPTER II II
GEOLOGICAL SETTINGS
Of
THE STUDY AREA
CONTENTS
2.1 Introduction
2.2 Geotectonic Setting
2.3 Regional Geological Set up
2.3.a Dongargarh Supergroup
2.3.b Chhattisgarh Supergroup
2.4 The Chhattisgarh Sedimentary Basin
2.5 Geology around Rajnandgaon & Parri Basin.
FIGUR~:-
2.1 Mid Late Proterozoic Basin of India.
2.2 Central India Craton & Tectonic Frame Wrok
2.3 Geological Map of Chhattisgarh Basin
2.4 Regional Geology.
2.5 Geological Map of Parri Basin
TABLE}-
2.1 Regional Stratigraphic Succession
2.2 Stratigraphic Succession of Chhattisgarh Basin
2.3 Geological Succession around Rajnandgaon
PLATt£:-
A. FIELD PHOTOGRAPHS
2.1 Field photograph showing horizontally bedded yellow Gunderdehi shale
upstream Nala cutting, location Chaitukhapri.
2.2. Field photograph showing debris of Gunderdehi shale exposure in
downstream of Parri Flood plain, East of Rajnandgaon.
2.3 Field photograph showing Gunderdehi shales exposure in river bed
showing joints NNW-SSE trend at South Manki lower reaches of Parri
Nadi.
2.4. Field photograph showing. Thick bedded grey limestone (Pachperi Mine)
2.5 Field photograph showing occurrence of sandstone as thin platy capping
overlies the thick masssive limestone.
2.6. Field photograph showing massive thick horizontal to low dip (2° NE),
grey limestone, location Chaweli quarry.
2. 7. Field photograph showing elephant's skin weathering in Raipur limestone
exposures along Nala Cutting east Parri, location 15 km mile stone
Rajnandgaon - Khairagarh Road.
2.8. Field photograph showing horizontal bedding planes and vertical joints
in limestone, location Chaweli Mines.
2.9 Field photograph showing Deodongar Sandstone exposures with promient
joints trend N-S, location, Chaweli Muhrum khurd road.
B. HANDSPECIMEN
2.1 0. Fine grained, Ferrugenous, red coloured Gunderdehi shale, showing
alternating Formation bands.
2.11. Gunderdehi shale showing colour variation from pink to Grey.
2.12. Limestone shows stromatolitic structure, secondary materials deposited
along intercolumn of this structure.
2.13. Pink Greenish grey stromotolitic limestone.
2.14. Red, compact, siliceous Deodongar sandstone.
2.15 Sedimentary concretion nodules of Parri Nadi bed.
C. PHOTOMICROGRAPHS :
2.16 Photomicrograph of Deodogar sandstone showing secondary growth in
quartz grains. (CN 40 x).
2.17 Photomicrograph of sub rounded coarse grained, Deodongar sandstone,
alteration of glauconite into ironoxide. (PL 40 x)
2.18. Photomicrograph of sandstone showing larger grains smooth and
subrounded shape. Small inclusions and cracks arer common in
sandstone. (CN 40 x).
2.19 Photomicrograph of limestone showing micrite and dolomite rhombshape.
(CN 40 x).
2.20. Photomicrograph of limestone showing calcite veins (sty/otitic vein) (CN
40 x).
2.21 Limestone composed of sparry canbonate Dolomite indentified by their
rhomb shape. (CN 40 x).
2.22 Gunderdehi shales showing sponge texture feldspar grain in centre. (PL
40 x).
2.23. Fine grained Gunderdehi shales composed of detrital grains of quartz,
feldspar and mica flakes are common (PL 40 x).
2.24 Ill sorted, fine grained shales, Brown mica biotite altered in epidote (light
yellow) (CN 40 x).
2.25 Shale showing quartz grains imbrication along the composition bandings.
(CN 40 x).
2.1 INTRODUCTION
The study area lies in the western portion of Chhattisgarh sedimentary
basin of proterozoic age. It is the largest sedimentary basin in Central India. The
Chhattisgarh basin having a crescent shape in outline and placed within the
Central Indian Craton.
The Proterozoic era is characterized by the development of mobile
belts, Sedimentary basins and the first stable cratons. (Fig. 2.1) Peninsular shield
of Centr<illndia experienced the development of thick sedimentary sequence in
form of large cratonic basin of Chhattisgarh as other world's shields (Raza,
Casshyap, 1996). The continental interior basins (intercratonic basins) are
typically oval in shape, symmetrical in profile and gave their depocentres at the
central part. These features are well represented in chhattisgarh basin.
A genetic relationships between the mobile belts and the Proterozoic
sedimentary basis are marked by the juxtapostion of the basin with their respective
proterozoic mobile belts as evidenced by their tectonic contacts and their relative
ages. (Harinarayan 1987, Raza and Casshyap, 1996)
2.2 GEOTECTONIC SETTING :-
The tectonic setup of the region includes this area in the Central India
Shield. The Central Indian Precambrian Shield (CIPS) is located in the north
part of the Indian Peninsular Shield and extended over the states of Madhya
Pradesh, Maharashtra and Uttar Pradesh. It occupies position in between the
cratonic mosaic of Singhbhum in the north east and Dharwar in the south.
There are two cratonic block and two intersecting mobile belts present
in the central India Precambrian shield Bundelkhand complex in the north and
the Bastar craton in the south are Cratonic blocks. The mobile belts are the N-S
trending Kotri·Dongargarh mobile belt in the Bastar craton and ENE-WSW
trending Central Indian Tectonic Zone (CITZ) in the Bundelkhand craton.
0
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MID LATE PROTEROZOIC BASI
l_v_. y ~ I 1: _·. : l
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2LESSER HIMAL~YA EQUII'LT.
3CHIIATTISGARH 13ASIN
41NDRAVATI BASIN
55UKUMA BASIN
6 GODAVARI VALLEY
RECENT Al.LUVIUM
MID-LATE PROTEROZOLCSASIN
Ei\RLV Mt{)-PROTEROZOIC
ME'1'A5i:DIMENTS FOLD BELT
BASEMENT 6RANrrEj GRANL'l'E GNEISSES
C.I.S.Z. CENTRAL INOlA SHEAR ZONE
G.B.F. Z. GREAT 130UN DAR Y FAULT lONE
S.NLZ. SON•NARMADA LINEAMENT ZONE
8 ,.
]2°
FIG.2J PROTEROZOIC BASINS OF I NDIAWto~RAZA)II$)
13
(Bandhopadhyay et. al., 1995).
Significant feature of the Central Indian Craton intersection of
Precambrian fold belt is the significant feature of them namely the N-S trending
Bengpai-Bailadila-Dongargarh belt in the south, E-W trending Sausar-Raigarh
belt in the north with Bhandara triangle between being occupied by the Sakoli
sequence. (Sinha, Roy, 1995). The Zone of intersection has been proposed by
some workers to represent a major suture (i.e. Central Indian Suture (CIS}
(Yedekar etal., 1990} Central India shield is a result of collage of two
protocontinents joined along a suture, called Central Indian Suture which
separates north Balaghat belt from south Dongargarh Supergroup. (Sarkar, 1994).
In the zone of west central part of Bastar Craton the Kotri Dongargarh Supergroup,
Sakoli Group an Sausar Group are included as proterozoic super crustal fold
belts.
The Proterozoic mobility of the west central part of the Central Indian.
Shield was ceased during 0.9-0.7 Ga, and this also represent the closing phases
of Sakoli, Sausar, Khairagarh Orogenies and emergence of Chhatisgarh and
other contemporaneous basins. (Bandhopadhyay et. al. 1995}. The
geotectonically Chhattisgarh basin is located within the Central Indian Shield,
includes Bastar granitoid craton and Sonakhan greenstone metamorphic belt in
south, in the north WNW-ESE trending Raigarh - Bilaspur metamorphics of
Satpura belt occur with a faulted margin. Eastern margin is characterized by the
granitoids of Bastar Craton and Eastern Ghat mobile belt are fringing the basin,
whereas Chilpi group of rocks, Dongargarh Granites and Kotri valconics are
juxtaposed in the West margin. (Fig. 2.2) (Ramakrishnan, 1990}.
The sedimentation in Chhattisgarh basin was initiated with the
formation of proto basins in the eastern-margin during the lower-Riphaean period
(Oas and D'suza, 1990) probably in the response to tectonic activity in NNE
SSW trending Eastern Ghat mobile belt in the east and NNW-SSW trending
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2.3 REGIONAL GEOLOGICAL SET UP :-
The regional geology of the terrain comprises rocks belonging to
Dongargarh and Chhattisgarh Supergroups. (Fig. 2.3j The thick sedimentary rocks
of Chhattisgarh Supergroup is deposited in an intercratonic basin (Pascoe, 1963)
and metasedimentary and metavolcanic rocks (Dongargarh supergroup) are
exposed in the west of the basin. The 90 km wide and 150 km long NNE
Dongargarh supergroup constitutes a major stratigraphic unit in the CIPS (Sarkar,
1957-58). The regional stratigraphic succession is given in Table 2.1. The details
are as follows.
2.3. (A) DONGARGARH SUPERGROUP :-
It comprises rocks of Nandgaon, Chilipiand Khairagarh groups. The
Nandgaon group consists of Bijli rhyolite and Pitepani volcanics of andesitic rock
formation.
AMGAON GROUP :
It is unconformably underlain by Nandgaon Group, consists of quartz
sericite & schist, felspathic- garnet epidote, hornablende schist & amphibolite.
A 1 BIJLI RHYOLITE :
The Bijli Rhyolite reprsents thick series of rhyolite with intertrappean
rhyolitic conglomerate sandstone, silitstone, shale & tuffs. These rocks
unconfrormably overlies the Amgaon Group,Sakoli Group rocks and Granitoid
gneisses. The folding of Bijli rhyolite took place during Nandgaon orogenic phase
and this event followed the extrusion of Pitepani volcanics. Colour range in rhyolite
is from white, grey, pink, black etc. with varying proportion of phenocrysts of
quartz, potash feldspar and albitic plagioclase.
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A2 PITEPANI VOLCANICS:
This unconformably overlies the Bijli rhyolites and includes
nonporphyritic to porphyritic tholeiites (with phenocryst of plagioclase) It is a
hard, compact greyish green in colour andesities and concoidal fracture.
Microscopically, it is fine to porphyritic in nature, in the matrix and laths of
plagioclase altered to oligoclase, and occur with chlorite, sericie calcite, epidote,
zoisite and dusty iron ore.
A3. DONGARGARH GRANITES:
It is formed later than Pitepani volcanics and this granite activity caused
a thermal metamorphic aureole up to 2.5 km. width adjoining Bijli rhyolite and
Pitepani volcanics. Porphyritic granite and coarse granite are common. Porphyritic
granite microgranite and granophyre also occurs. Relict inclusion and transitional
stages of rhyolite indicate insitu granitization in the area.
CHILPI GROUP:
It separates the Nandgaon group from the Khairagarh group of rocks.
The slaty Shale rock is a pelitic member which is a predominant rock followed by
arkose and grey wacke. Its colour ranges from red to purple. Slaty shale occurs
in Chilpi Gath Group rocks are correlatable with Khairagarh Group and Khairagarh
grade Chilpi Ghat rocks (Sarkar, 1994).
KHAIRAGARH GROUP:
This group consists Bortalao formation, Sitagota Volcanics, Karutola
Formation and Mangikhuta volcanics. Folded rocks of Khairgarh group represent
their fold axes and axial trend in NNE-SSW orientation.
BORTALAO FORMATION :
This is the lowermost formation which unconformably overlies the
volcanic rocks of Nandgon Group or the Dongargarh Granites. This formation
TABLE2.1
REGIONAL STRATIGRAPHIC SUCCESSION (AFTER SARKAR, 1994)
Dolerite dykes and sills Chhattisgarh Supergroup Raipur Limestone :
Chandarpur Sandstone :
Compact - nodular limestone, purple shale Fine purple sandstone
---------------UnconformitY------------
~ 0
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0. ::::J 0 a: (!)
I a: ...: CJ ...: a: ...: I ><
0.
Quartz veins Sillicified fault breccia Hypabyssal diorite, gabbro, pyroxenite, acid porphyrate
_______ Khairagarh Orogenic phase (c.900 Mal----------
Mangikhuta Volcanics (> B10m)
Hypabyssal phase of tholeiite Pyroxene/olivine basalts (tholeiitic) with minor intertrappean shales, siltstones & tuffs
Karutola !ormation Ferrugineous orthoquartzites Cross-bedded mature sandstones (!170m)
Sitagota Volcanics ( < 1500m)
Bortalao Formation (<2040)
Hypabyssal phases of basalt & andesite Tholeiitic basalts ( 1367 Ma, porphyritic, nonporphyritic & amygdaloidal) Basic tuffs & agglomerates lntertrappean shales & siltstones (tf'PR Ma)
Green (mature) sandy tuffs & tuffaceous sandstones (<1110 m) Upper conglomerate (<300m) Arkosic & lithic wackes & arenites (cross bedded) Arkosic & rhyolitic sandstones with pebbly horizons Lower conglomerates (<120m) Shales & siltstones, basal (1534 Ma)
'---------------Unconformity-------------Dongargarh granite (2270 ± 90 to 2465 ± 22 Ma)
Pitepani Volicaics (<1690m)
Micro granite & aplite ; coarse & porphyritic granite Porphyritic micro granite and granophyre.
Hypabyssal gabbro & dioritic units, porphyry non-porphyritic, porphyritic & amygdaloidal tholeiite Basic tuffs & agglomerates Shales & siltstones
6 Nandgaon Orogenty (Unconlormity) -----------a: C!J ~ Bijli Porphyritic & non-porphyritic rhyolites, rhyolite porphyry (flow layers) z 0 Rhyolites Rhyolitic conglomerate, sandstones, siltstones, shales & tuffs (300 m) oo (3 ~ 1----------Unconformity-------------------
~ Rhyolite with flow layers (2180-2503 Ma) ...: z Unconformity -------------------
Amgaon Group
Amgaon Orogeny, metamorphism & granitisation (>c.2500 Ma) Quartz sericite. schist, feldspathic-, garnet epidote, hornblende biotite- quartzite : quartz-feldspar-biotite gneiss, augen gneiss, hornblende schist & amphibolite.
includes shales, silt stone, basal conglomerate, arkose, sandstone, tuff
sandstone, well rounded pebbles cobbles and boulders of Bijli rhyolite. It consists
of felspathic s/st, argilitic s/st. The sandstone is composed of quartz, chert pebbles
of granitic and and andestic composition in ferrugineous matrix. Lower
conglomerate is made up of Dongargarh granites, arkose vein quartz in finer
grained matrix. Pale to dark grey rhyolitic s/st and upper conglomerate consists
of well rounded pebbles of white quartz.
SITAGOTA VOLCANICS :
It comprises dull green (augite) theoleiites with minor tuff and
aglomerates. These basic lavas occurs as synclinal outliers flanks of Sitagota
syncline. The rock is hard and compact, dark green in colour, composed of quartz,
microcline, perthite, oligoclase and andesite.
KARUTOLA FORMATION :
This fomation disconformably overlies the Sitagota volcanics. It
consists of fine to coarse granied well bedded pure and ferrugenous
orthoquartzites with grains showing high degree of roundness.
MANGIKHUTA VOLCANICS:
This group volcanic rocks overlying Karutola formation and occurs as
outlier in Sitagota syncline. It consists of non-porphyritic, amygdoidal pyroxene
tholeiites with minor intertrappean shales and silt stones with a colour variation
from dark green to dark black.
3.38. CHHATTISGARH SUPER GROUP:
The rocks of Chhattisgarh supergroup overlies unconformably over
the rocks of Dongargarh supergroup. It comprises arenaceous calcareous and
argillaceous facies of rocks. (Dutt, 1964, Murti, 1967)
2.4. THE CHHATTISGARH SEDIMENTARY BASIN :-
This basin can be divided into Hirri and Baradwar subbasins. (Fig.2.4)
The early initiation sedimentation have taken place in the Baradwar sub basin
which lies on the eastern part of the basin. A major activity of basin evolution is
witnessed by the Singhora end phase of sedimentation when huge areas on
either side of Sonakhan high lands subjected to large scale subsidence. This
gave rise development of two-basin within the Chhattisgarh domain. The Hirri
sub basin is referred to as the main basin in the west having circular to elliptical
shape. The oldest rock formation of Chhattisgarh basin in Singhora Group and
presented in Singhora area lying east of Sonakhan (Das et. al. 1992). The
depositional environment of Chhattisgarh basin is coarse silicic clastic beach
near shore coastal but limestone and chert represent deeper marine setting.
(Murti, 1987). There is possibility of regional linkage between the Vindhyan and
Chhattisgarh basin by a master basin (Mitra, 1996).
GEOLOGY OF THE CHHATTISGARH BASIN:
The entire succession of Chhattisgarh basin is classified into three
groups. The lowermost is the Singhora Group, developed in the east consisting
of four formations of arenite, argillite, and carbonate sequence. The middle group
Chandrapur Group, unconformably overlying the lower group. This middle group
consists of three formation of arenite litho-assemblage namely Lohardih,
Chapordih and Kansapathar. The upper group is Raipur Group, consisting argillite
carbonate suite and subdivided into six formations, Charmuria, Gunderdehi,
Chandi, Tarenga, Hirri and Maniari successively. (Table 2.2, Fig 2.4).
CHANDRAPUR GROUP:
In Hirri basin the lower arenaceous Chandrapur group rest
uncomformably over the unclassified granites and gneisses of Archean age. It is
well developed along eastern and southern boundary of Chhattisgarh basin. It is
R
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u R
TABLE 2.2
STRATIGRAPHIC SUCCESSION OF CHHATTISGARH BASIN (After DAS et. al., 1992)
G
R
0
u p
Intrusives
Maniari Formation (70m)
ffirri Formation (?Om +)
Tarenga Formation (180m?)
Chandi Formation (670m)
Gunderdehi Formation
Charmuria Formation (490m)
Kansapalhar Formation (20·200m)
Chaporadih Formation (20-20m)
Lohardih Formation (20m)
Bilha Member
Dagauri Member
Kusmi Member
Nipania Member
Pendri Deodongar Member
Newari Member
Andha/Dolopath Member in the middle
Bagbura Member
Kasdol Member
Ranidhar Member
Sirpur Member -
Dolerite dykes
Purple shale w1th dolom1te, do!om1tic limestone and gypsum.
Grey dolomite, argillaceous dolomite.
Purple dolomitic argillite
Green clay, chert and shale Intercalation (tuffaceous ?}
Pmk to Purple calcareous shale,
Purple and green bedded limestone Purple argillaceous stromatolitic dolomite.
Purple and grey stromatolitic limestone and dolomite With flaggy limestone shale intercalation /lerrug1onus glauconitic arenite and shale.
Pink and buff stromatolitic limestone and dolomite
Predominantly pink, purple and grey shale with limestone intercalations/arenite/bull to green shale member in the middle.
Purple limestone (Phosphatic)
Dark grey bedded limestone/argillaceous limestone With mmor shale intercalation
Cherty limestone and dolomite (phosphalrc at places }
Chert and clay 1ntercalat1on.
Glaucon111c white to pmkish quartz aren1k.
Purple, green, grey and black, shale with Siltstone/quartz arenite Wlfil shale mtercalat1on
Ferrug1nous purple arkose and gr~tty wacke arenite With shale partings and conglomerate at the base
---------------Unconformity ______________ _
s I
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G
H
0
R
A
G
R
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u p
Chhuipali Formation (300m ?)
Bhalukona Formation (20 m±)
Saraipali Formation (60m)
Rehalrkhol Formatron (20m +)
Slromalolilic limestone and dolomite, variegated shale with minor bedded limestone, chert and siltstone intercalations,
Quartz arenite/siltstone and minor shale.
Veriegated shale with siltstone chert and minor limestone.
Feldspathic arenite. Arkose and conglomerate al the base.
---------------- Unconlormrty ----------------Archean and Lower Proterozorc basement
divided in to Lohardih, Chapordih and Kansapathar formation in successive order.
(Murti, 1987, Das et. al, 1992).
LOHARDIH FORMATION :
About 20 metres thick formation comprises conglomerate, arkose and
sand stone. The basal conglomerate grade into ferrugenous purple subarkosic
sandstone which contains subangular to subrounded grains of quartz and
felspars.
CHAPORDIH FORMATION:
It comprises purple, green grey and black shale with silt stone I quartz
arenite and conformably overlie the Lohardih formation. Shale intercalations are
common features. Glauconite and mica flakes generally present.
KANSAPATHAR FORMATION :
Kansapathar formation conformably overlie the Chapordih formation.
This formation comprises mainly of white to pinkish and medium to coarse grained
arenite.
RAIPUR GROUP:
The Raipur Group is divided into six formations.
CHARMURIA FORMATION :
It consists of four members mainly comprises flaggy limestones. Clay
intercalations and Cherty bands are common upwardly. Clays are thinly laminated.
GUNDERDEHI FORMATION:
It conformably overlie Charmuria limestones which is dominantly a
calcareous argillite developed as a distinct facies in the sub-basin. It comprises
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purple coloured shales with intercalated limestone. These are highly friable in
character. It grades into black shales. The purple shales are fine to medium,
grained & breaking into splinters. Authigenic glauconite is common. The purple
shales show at places grey shaly units (Murty, 1987).
CHAND/ FORMATION :
It is divided into three members successively Newari, Pendri and
Nipania. This comprises a major stromatolitic limestone sequence developed
around southern side of Hirri subbasin with an arcuate outcrop pattern. In the
west two carbonate members Newari and Pendri fused into a single carbonate
sequence. Chandi formation overlies Gunderdehi shales with a gradational
contact. Das et. a/ (1992) have recognized one more member Deodongar and
positioned equivalent to Pendri member.
NEWARI MEMBER :
It contains pink and light grey limestone, Extensive development of
stromatolitic structure occurs and beds are thick. Dolomitization of limestone
takes place along joints & fissures.
PENDRI MEMBER I DEODONGAR MEMBER :-
It is the heterogenous unit comprising dark grey fine grained
stromatolitic limestone and flaggy limestone associated with green calcareous
shale pockets. The falggy limestone is composed of micrite calcite, clay and
quartz. The clay and fine clastics are alternately arranged, imparting a flaggy
appearance to the rock. The green shale is friable, splintery, calcareous and at
places itself contains columnar stromtolitic structure inclined to bedding plane.
Deodongar member is developed as intercalated ferrugenous arenite unit of
discrete lensoid shape in southern part of Hirri subbasin (Mishra, Rao, 1990).
The rock is coarse fine grained and reddish brown to brown in colour. It is beded
and shows cross bedding and ripple marks. Dull (1964) described a ferrugenous
arenite band as Khairagarh member which is described later as Deodongar
member occurs in Gunderdehi as separate unit and is not correlatable with the
arenite of Khairagarh area. (Das et. al. 1992).
NIPANIA MEMBER :
It compries purple and green bedded limestone with purple shales.
Stromatolites are also present.
TARENGA FORMATION :
This formation consists of pink and purple coloured shales with
interbedded cherts green clays occur as intercalations.
HIRAI FORMATION:
It consists of argillaceous dolomite and grey dolomites with black shale
pockets.
MANIARI FORMATION :
It conformably overlies Hirri formation and composed of purple shale,
dolomite and gypsum intercalations.
2.5 GEOLOGY AROUND RAJNANDGAON & PARRI BASIN :
The study area is underlain by rocks belonging to the Chhattisgarh
supergroup. (Fig. 2.5) Stratigraphically, the investigated area comprises of oldest
Gunderdehi shale formation overlain by Chandi formation. Both are of Raipur
Group rocks. The Gunderdehi formation occurs in southern portion in form of
shale member where as the overlying Chandi formation occupied in north east.
section and comprises limestone (Pendri) and sandstaone of Deodongar
members. Isolated laterite cappings are seen around mounds at some basin
margin areas. Only Raipur Group of Chhattisgarh super group rocks are exposed
21° IS'
s( o'
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SCALE
21" IS'
INDEX 2.5 0 2.5 Km
Rocf<. rypes
: _..I Deodongor Sandstone
1,' 1 1
1 11 Chondi Limestone
~----_:-I Gunderdehi Shale
FIG. 2.5 GEOLOGY OF PARRI BASIN
in the investigated area. The geological succession of investigated area around
Rajnandgaon and Parri Nadi Basin has been given in table 2.3. The geological
map is prepared on the basis of literatures, field investigation, photogelogical
mapping and IRS Remote sensing Image interpretation and Dutt, (1964) and
Das et. al, (1992) Murti, (1987) stratigraphic classification.
TABLE 2.3
GEOLOGICAL SUCCESSION AROUND RAJNANDGAON (GENERALISED)
The brief megascopic & microscopic characteristecs of lithotypes,·
outcrops, localities and samples studied are described as follows-
SHALE:
Southern part of the area of Parri basin is occupied by Gunderdehi
shales of Raipur Group. The thickness of shale gradually inereases towards south
of the Parri Basin and around Rajnandgaon city. The ground surface is covered
with thick soil mantle (thickness 5-B metres) and out crops seen only along stream
cutting and dug well section. (Field photo plate 2.1 ). Shales vary in colour from
green to dark brown and purple. These occurs as bands of single colour but at
places these are intermingled in each other and do not show sharp contact. The
purple shale is exposed along Parri Nadi section in lower reaches (Field photo
no. 2.2 & 2.3). The other localities are Ruwatola, Rengankathera, Tilai, Dilapahri
and Dhaba in middle and west part of Parri basin.
Megascopically, it shows pinkish red to greenish grey colour, thin
laminations, fine grained and impermeable nature. It is highly friable and sets of
joints generally developed at right angles. The Purple colour is due to presence
of ferrugenous matter. A brief description of megascopic characters in hand
specimen of shale is given below.
HAND SPECIMEN- CHGS :
It is green coloured, very thinly banded shale with a friable nature. It
splits along plane of laminae. These laminae formed at the time of deposition.
HAND SPECIMEN - Sh 1 :
This is a dark purple coloured shale. The presence of thin bands is
numerous and splits along this plane. It acts as a separation plane and which
form the compositional bands. (Plate 2.1 0).
HAND SPECIMEN - Sh 2 :
This specimen shows gradually a fading out contact between green
and pink shale which is due to increase in ferrugenous materials. (Plate 2.11)
Microscopically, shales are ill sorted, highly ferrugenous with 20-30%
quartz and remains are clayey matter. The compositional bands represents
alternate high ferrugenous and less ferrugenous bands. The quartz grains show
imbrications along compositional bandings. Detrital quartz is highly angular and
micaceous grains presents as minor constituents.
THIN SECTION Sh 1 :
This brown red coloured shale in thin section under polarised light
look like a deep brown spongy mass covenring whole of field viewed. (Plate
2.22).
THIN SECTION- CHGS:
It is a fine granied argillaceous rock composed of detrital granules of
quartz feldspar and mica flakes. Quartz occurs anhedral and angular grains where
as feldsprs are subhedral in shape. (Plate 2.23).
THIN SECTION Sh. 3 :
It is ill sroted, fine grained, abundance of clayey matter. Minute cracks
and inclusions are common in quartz. Brown mica biotite altered into epidote
(light yellow) and limonite has formed as a result of separation of iron oxide.
(Plate 2.24)
THIN SECTION SL 2:
The quartz grains show imbrications along the compositional bandings.
The fine grained groundmass is composed to a great extent by very finely divided
micaceous substance of secondary origin (Plate. 2.25).
LIMESTONE:
The limestone is dark pink to grey in colour and thickly bedded. (Field
photo plate 2.4). Good exposures are found only in nala cutting and quarry section
of north and east margin ot the basin, near Chaweli, Pachperi and Thelkadih .
(Plate 2.6 and 2.8) Presence of Minor shale partings are common features within
limestone beds of varying thickness. Stromatolitic limestones are grey to brown
in colour and intercolumnar space is generally filled with argillaceous carbonate
material. On surface Elephant's skin weathering is common (Plate 2.7). The
limestone outcrops show wide joints, fissures and karstic Features. Secondary
porosity due to joints and solution cavities are well developed in stromtolitic
limestones. Under microscope the limestone composed of sparry carbonate,
Dolomite identified by their rhomb shape (Plate 2.21 ). The characteristics of some
hand specimens are given below.
HANDSPECIMEN CHLS :
This specimen shows algal structure of stromatolytes. It is hard and
compact in nature. Karstic freatures developed along column of stromatolites.
(Plate 2.12).
HAND SPECIMEN LS3:
This specimen is green in colour, fine grained hard and compact with
reddish spotts. This reddish brown of the shade is due to presence of iron. Thin
laminations are common feature and these are indicative of original clastic nature
of calcite. (Plate 2.13).
THIN SECTION LS3:
In thin section the limestones are composed of sparry carbonate
occurring as equidimensional polygonal aggregate forming the mosaic dolomite
grains are identified by their rhomb shape. (Plate 2.19).
THIN SECTION LS1 :
Under microscope this section shows sparry carbonate composed of
big calcite grains occur as irregular bands of varying thickness. Small grains of
iron oxides are common and show dark brown to black colour. Rhombs of dolomite
grains are scattered throughout the limestone. Calcite stylolite vein extends E-W
direction. {Plate 2.20 ) in the middle of the field and limestone shows micrite and
dolomite rhomb.
SANDSTONE :
Ferrugenous glauconitic sand stone exposed as capping rock in north
east mound of the Parri Basin. Good exposures are found to the east of Chaweli
- Muhrumkhurd road {Plate 2.5 & 2.9). The outcrops occur 330 meters above
mean sea level and due to highly ferrugeuous nature it has been affected by
intensive weathering and occurs as thin platy laminations. Two sets of joints are
common of which N-S is prominent direction in the study area {Plate 2.9). The
sanstone is well sorted, with subrounded to rounded quartz grains, having
authingenic over growth {Plate 2.16). It is coarse grained with ferrugenous
cementing material, low angle cross bedding is common feature. Mineralogically,
the rock is composed of 90% quartz, about 5% glauconite, 2.5°io feldspar and
heavy minerals. The general modal composition of sandstone range as follows
Qartz 70-80%, Chert 10-15%, Feldspar 10-12%, Cement- 1-2%.
HAND SPECIMEN SS1:
The colour varies from dark brown to red. The rock is hard & compact.
It is coarse granied ferrugenous sandstone with colour bands. It has siliceous
cementing material. (Plate 2.14)
THIN SECTION SS1:
It shows moderately sorted coarse grained nature of the rock. The
subangular and subrounded quartz grains are closely arranged with recrystallized
siliceous cementing material. The grain size vary from 0.1 to 0.04 mm. Authigenic
overgrowth around quartz grains are very commom. A chain of inclusion
26
(commonly dark coloured) defining the overgrowth outline of the grain.
(Plate 1. 7).
THIN SECTION SS2 :
The quartz grains are subrounded. A good proprotion of elongated
quartz grains are present. Larger grains have relatively smooth and sub rounded
outline. Undulose extinction is not common. Most of the quartz grains contain
small inclusions. Small cracks have also been recorded. (Plate 2.18).
LATERITE:
Laterite occurs as cappings over mounds of sandstone and uplands
in water divide zone. It is scattered throughout the basin. The thickness vary
from place to place to and range is 0.025 meters to 2.00 meters. The pisolites
are medium sized and vary in colour from deep red to black.
ALLUVIUM:
Recent alluvium in Parri Basin confined mainly along river course where
sinuosity and meandering is prominent. In Seonath river old paleochannels
marked near Bharregaon. Thickness of alluvium in flood plains vary from 2 to 6
meters. Extensive land use is common feature in these old flood plains. Alluvium
contains medium to fine sand, silt and clay contents. Sedimentary concretionary
nodules of recent origin commonly occurs in Parri stream (Piate-2.15).
PLATE 2.1 HORIZONTALLY BEDDED YELLOW GUNDERDEHI SHALES UP STREAM NALA CUTTING, LOCATION CHAITUKHAPRI. .
PLATE 2.2. DEBRIS OF GUNDERDEHI SHALE EXPOSURE IN DOWN STREAM PARRI FLOOD PLAIN, EAST OF RAJNANDGAON. OF
PLATE 2.3. GUNDERDEHI SHALE EXPOSURE IN RIVER BED SHOWING JOINTS: NNW • SSE TREND AT SOUTH MANKI, LOWER REACHES OF PARRI NADI.
I
PLATE 2.4. THICK BEDDED GREY LIMESTONE (PACHPERI MINE).
PLATE 2.5 OCCURRENCE OF SANDSTONE AS THIN PLATY CAPPING OVERLIES THE THICK MASSIVE LIMESTONE.
PLATE 2.6 MASSIVE, THICK, HORIZONTAL TO LOW DIP (2° NE), GREY LIMESTONE, LOCATION CHAWELI QUARRY.
P L A T E 2.7. ELEPHANT'S SKIN WEATHER ING IN RAIPUR LIMESTONE EXPOSURE ALONG NALA CUTTitJIG EAST PARRI, LOCATION 15 KM MILE STONE RAJNANDGAO N • KHAIRAGARH ROAD.
PLATE 2.8. HORIZON T AL BEDDING PLANES AND VERTICAL JOINTS IN LIMESTO NE LOCATION CHAWELI.
PLATE 2.9 FIELD PHOTOGRAPH SHOWING DEODONGAR SANDSTONE WITH PROMINENT JOINTS TREND, N-S, NEAR CHAWELI • MUHRUMKHURD ROAD.
PLATE 2.10. FINE GRAINED, FERRUGENOUS RED COLOURED GUNDERDEHI SHALES, SHOWJNG AL TERNATJNG FORMATION BANDS.
PLATE 2.1 1. COLO UR V ARIATION FRO M P IN K TO GREY I N G UNDERDEHI SHALES.
PLATE 2 .12. LIMESTONE SHOWING STROMATOLITIC STRUCTURE, SECONDARY MATERAILS DEPOSITED ALONG INTER COLOUMNS OF THIS
PLATE 2.13. PINK G~EENISH GREY STROMATOLITIC LIMESTONE.
PLATE 2.14. RED, COMPACT, SILICEOUS DEODONGAR SANDSTONE.
PLATE 2.15. SEDIMENTARY CONCRETION NODULES OF PARRI NADI BED.
PLATE 2.16. PHOTOMICROGRAPH OF DEODONGAR SANDSTONE SHOWING SECONDARY GROWTH IN QUARTZ GRAINS (C.N .40X)
PLATE 2.17. PHOTOMICROGRAPH OF COARSE GRAINED, DEODONCAR SAN DSTONE , SHOWING SUBROUNDED QUARTZ GRAIN, ALTERATION OF GLAUCONITE INTO IRON OXIDE. (P.L. 40X).
PLATE 2.18. PHOTOMICROGRAPH OF SANDSTONE SHOWING LARGER CRAIN, SMO OTH AND SUBROUNDED SHAPE. SMALL INCLUSIONS AND CRAC KS ARE COMMON IN SANDSTONE (C.N. 40X)
PLATE 2.19 PHOTOMICROGRAPH OF LIMESTONE SHOWING MICRITE AND DOLOMITE RHOMB (C. N. 40X)
PLATE 2.20. PHOTOMICROGRAPH OF LIMESTONE SH OWING CALCITE VEINS (STYLOLITE VEIN) (C.N. 40X)
PLATE 2.21 LIMESTONE COMPOSED OF SPARRY CARBONATE. DOLOMITE IDENTIFIED BY THEIR RHOMB SHAPE (C. N. 40X)
PLATE 2.22. GUNDERDEHI SHALES SHOWING SPONGE TEXTURE FELDSPAR GRAINS IN CENTRE (P. l. 40 X)
PLATE 2.23. FINE GRA INED GUNDERDEHI SHALES, DETRITAL GRAINS OF QUARTZ, FELDSPAR AND MICA GRAINS ARE COMMON (P. L.' 40X)
PLATE 2.24. ILL SORTED FINE GRAINED SHALES, BROWN MICA BIOTITE ALTERED IN TO EPIDOTE (LIGHT YELLOW) (C. N . 40 X)
PLATE 2.25. PHOTOMICROGRAPH OF SHALE : QUARTZ GRAIN SHOWING IMBRICATION ALONG THE COMPOSITIONAL BANDINGS. (C. N. 40 X). •