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Laboratory of Orogenic Belts and Crustal Evolution, Peking University, China Institute of Geology, Chinese Academy of Geological Sciences, China

Mendel University in Brno, Czech Republic Tescan, a.s., Czech Republic

Deposits of critical metals

and related carbonatite-alkaline rock systems

Jindrich Kynicky

Anton Chakhmouradian

Hana Cihlarova

Zengqian Hou

Lifei Zhang

Cheng Xu

(Eds.)

2012

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Deposits of critical metals and related carbonatite-alkaline rock systems

Critical metals are metals whose availability is essential for high-technology, green

and defense applications, but prone to supply restrictions. At present, this designation applies particularly to the rare-earth elements (REE), whose supply market has been undergoing major changes in the past several years; a range of other metals (e.g., niobium and tantalum) are also considered critical.

The first workshop on deposits of critical metals and related alkaline-carbonatite rock systems was organized during September 4-7, 2012, at Peking University, China. The meeting will address the origin and evolution of these deposits and specifically REE-bearing systems (carbonatites and associated alkaline rocks, hydrothermal, metasomatic and residual deposits) with a particular emphasis on their mineralization and economic potential. A special session will be held on the localities of alkaline rocks and carbonatites in China, Mongolia and Russia. Geologists, petrologists, mineralogists, geochemists, explorationists, technologists and market specialists are all welcome to contribute to this cutting-edge workshop. CM2012 was financially supported by the Tescan, a.s., (Czech Republic); Laboratory of Orogenic Belts and Crustal Evolution (Peking University); IGCP-600 program (Institute of Geology, Chinese Academy of Geological Science); Chinese National Science Foundation (Nos. 40973040, 41173033); Mendel University in Brno (Czech Republic) and CEITEC CZ.1.05/1.1.00/02.0068.

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Workshop Program

Day 1, Tuesday 04 September –Yifu 2nd Building, Peking University

15:00-18:00 Registration at Yifu 2nd Building, School of Earth and Space Sciences

18:00- Icebreaker party at Xihua hotel

Day 2, Wednesday 05 September – Peking University, International Center for Mathematical Research

8:20-8:30 Opening address

Host Zengqian Hou

8:30-9:00 Keynote: Prof. Frances Wall, University of Exeter, UK Report title: UUURare earth deposits associated with carbonatite complexes – where are the heavy rare earths?

Session 1: Carbonatites and alkaline rocks: Magmatic evolution, subsolidus hydrothermal overprint, and processes leading to deposits of critical metals

9:00-9: 25 Prof. Cheng Xu, Peking University, China Report title: UUUCrustal recycling vs. rare Mo mineralization related with carbonatites

9:25-9:50 Prof. Pavel Uher, Comenius University, Slovakia Report title: UUUThe REE-Ti-Nb-Ta oxide minerals: from crystal chemistry to ore deposits

9:50-10:10 Tea break

10:10-10:35 Prof. Daniel Harlov, Helmholtz-Zentrum Potsdam, Germany Report title: UUUReprecipitation textures and REE redistribution in REE mineral associations

10:35-11:00 Prof. Martin Ondrejka, Univerzita Komenského, Slovakia Report title: UUUDestabilization of REE bearing accessory minerals under rock-fluid interaction conditions

11:00-11:25 Dr. Martin Smith, University of Brighton, UK Report title: UUUHydrothermal process in REE enrichment and fractionation

11:25-11:50

Dr. Mihoko Hoshino, National Institute of Advanced Industrial Science & Technology, Japan Report title: UUUCrystallization process of zircon and fergusonite during hydrothermal alteration in Nechalacho REE deposit, Thor Lake, Canada

11:50-12:10 Masterate student Lize Wang, Peking University, China Report title: UUUThe genesis of ion adsorption type REE+Y deposits of Granitoids in Dingnan region, Jiangxi Province, Southern China

12:10-2:00 Lunch break

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Session 2: New analytical methods and HT experiments for carbonatites-alkaline rocks and associated deposits Host Anton Chakhmouradian

2:00-2:25

Dr. Ilya V. Veksler, GFZ German Research Centre for Geosciences, Germany Report title: UUUExperimental data on element partitioning between immiscible silicate and carbonate liquids with implications for the origin of rare metal deposits in carbonatites and alkaline rocks

2:25-2:50 Associated Prof. Shuangmeng Zhai, Peking University, China Report title: UUUTrace elements in tuite experimentally decomposed from natural apatite

2:50-3:15 Associated Prof. Qiong Liu, Peking University, China Report title: UUUEquation of state for carbonate liquids and implications to deep earth carbon recycle

3:15-3:40 Dr. Veronika Králová Report title: UUUTIMA – TESCAN Integrated Mineral Analyzer: New approach for rapid evaluation of critical elements ore samples

3:40-4:00 Tea break

4:00-4:25 Dr. Ekaterina Reguir, University of Manitoba, Canada Report title: UUUThe importance of trace-element analysis for petrogenetic studies and mineral exploration (as exemplified by carbonatites)

4:25-4:50 Prof. Liang Qi, Chinese Academy of Sciences, China Report title: UUUA new type of Carius tube for the determination of Re-Os and PGE in geological samples

4:50-5:15 Prof. Yan Liu, Chinese Academy of Geological Sciences, China Report title: UUUHimalayan mountains and south Tibetan plateau: a larger reservoir for atmospheric CO2 since Late Miocene

5:15-5:35 Doctoral student Hongming Zhang, China University of Geosciences, China Report title: UUUIsotope tracing deep carbon cycle

5:35-5:55

Masterate student Yi Sun, Peking University, China Report title: UUUREE and rare metal element mobility and mineralization during magmatic and fluid evolution in alkaline granite system: Evidence from In-Situ LA-ICP-MS study of melt inclusions in Baerzhe granite

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Day 3, Thursday 6 September - Peking University, International Center for Mathematical Research

Host Jindrich Kynicky

8:30-9:00 Keynote: Prof. Anton Chakhmouradian, University of Manitoba, Canada Report title: UUUPostorogenic carbonatites and their significance for rare-metal exploration and geodynamic analysis

Session 3: Strategic REE deposits in China, Mongolia and Russia

9:00-9:25 Prof. Xiangkun Zhu, Chinese Academy of Geological Sciences, China Report title: UUUGenesis of the Bayan Obo REE-Fe-Nb deposit

9:25-9:50 Prof. Tiegeng Liu, Chinese Academy of Sciences, China Report title: UUUGeological and geochemical characteristics and genesis of “dolomite” at Bayan Obo, China

9:50-10:10 Tea break

10:10-10:35

Dr. Ulf Kempe, TU Bergakademie Freiberg, Germany Report title: The genesis of Zr-Nb-REE mineralisation at Khalzan Buregte (NW

Mongolia) reconsidered

10:35-11:00 Dr. Jindrich Kynicky, Mendel University, Czech Republic Report title: UUUREE deposits of Mongolia

11:00-11:25 Dr. German S. Ripp, Russian Academy of Sciences Geological, Russia Report title: UUUSr- and REE carbonatite deposits of the West Transbaikalia, Russia

11:25-11:50 Dr. Anna Doroshkevich, Russian Academy of Sciences Geological, Russia Report title: UUUNew mineralogical and isotopic data on Nb- and REE carbonatite deposit Belaya Zima, RussiaUUU

11:50-12:10 Dr. Yan Liu, Chinese Academy of Geological Sciences, China Report title: Some progresses for the study of Dalucao LREE deposit, Sichuan, SW China

12:10-2:00 Lunch break

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Session 4: The global picture: critical metals deposits worldwide. Host Cheng Xu

2:00-2:25 Dr. Clint Cox, Anchor House, Chicago, America Report title: UUUSome Economic Factors to Consider in Mining and Processing Rare Earths - past, present and future of REE mining

2:25-2:50 Dr. Milan Hauser Report title: UUUIntroduction of the TESCAN Company and Product Line useful in quick analyse of ores and associated mineralsUUU

2:50-3:15 Doctoral student Wenlei Song, Peking University, China Report title: UUUGeological and geochemical guidebook for fieldtrip in Huanglongpu Mo depositUUU

3:15- Tea break and Photo

7-10th September

Fieldtrip in Huanglongpu Mo deposit

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TIMA – TESCAN Integrated Mineral Analyzer: New approach for rapid evaluation of critical elements ore samples

Veronika Kralova1, David Motl1, Jindrich Kynicky2 1TESCAN, a.s., Czech Republic; 2 Department of Geology and Pedology, Mendel University, Czech Republic

The Czech company TESCAN is one of the global suppliers of scientific instruments. Within 20 years of its existence, the TESCAN brand has built its reputation particularly in designing and manufacturing scanning electron microscopes, system solutions for micro- and nanotechnology, and a wide range of other applications.

For analytical work in the fields of mineralogy and geology, TESCAN has developed a new automated mineralogy solution, which enables fast and effective data acquisition and accurate and reliable data analysis. TESCAN Integrated Mineral Analyzer (TIMA) combines BSE and EDX data to automatically measure mineral abundance, mineral liberation and association, particle and grain sizes, and bright particles, on multiple samples of grain mounts, thin sections or polished sections. TIMA can find its application in ore characterization, search for precious metals and rare earth minerals, remediation, and many other areas.

TIMA has been tested and used for the examination of various samples. The most important of them were samples of fresh and metasomatically modified carbonatites from the Lugiin Gol (a.k.a. Lugingol’skiy) complex in the South Gobi, Mongolia. The samples chosen represent not only rare carbonatite outcrops, but also drill-core material (down to a depth of 1200 m) that had not been previously studied. The carbonatites are represented predominantly by coarse-grained sövite, consisting of magmatic calcite and a plethora of rare-earth carbonates whose modal content locally reaches 30 %. The latter group is paragenetically diverse and includes both primary carbonates (burbankite–calcioburbankite series and REE fluorocarbonates) and hydrothermally or metasomatically formed phases associated with strontianite, ankerite and fluorite. The primary fluorocarbonates are represented by zoned synchysite-(Ce) and parisite-(Ce).

Using scanning electron microscope together with various detectors helps to identify mineral species in detail and is a powerful tool for better understanding of ores and ore deposits in general. TIMA, additionally, allows acquiring data automatically with high data acquisition speed and processing them in the same time, providing various types of analyses depending on required results.

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Crustal recycling vs. rare Mo mineralization related with carbonatites

Cheng Xu 1, Jindrich Kynicky2, Anton R. Chakhmouradian 3

1Department of Geology, Peking University, China; 2 Department of Geology and Pedology, Mendel University, Czech; 3Department of

Geological Sciences, University of Manitoba, Canada

Collision-related carbonatites are rare and raise questions about the role of crustal recycling in their genesis. Most carbonatites are very poor in Mo, whose levels are at or below the limit of detection. In this work, we report a new type of carbonatite-related Mo deposit. At Huanglongpu (HLP), economic molybdenite mineralization is associated with calcite carbonatites emplaced in the Lesser Qinling orogenic belt. The deposit has an ore reserve of > 0.18 million tons of MoS2. The HLP carbonatites are characterized by unusually high levels of heavy rare-earth elements (HREE: e.g.,> 30 ppm Yb) and flat to weakly light-REE-enriched chondrite-normalized patterns [(La/Yb)n=1.0-5.5], which is in marked contrast with mostk nown carbonatites. Their C and O isotopic compositions are consistent with a mantle source, and do not indicate any secondary processes that could lead to HREE enrichment. The carbonatites intrude a variety of Archean and Mesoproterozoic wall-rocks, but are characterized by remarkably similar isotopic compositions [(87Sr/86Sr)i = 0.7048-0.7057; εNd = -4.3 to -10.1; 207Pb/206Pb = 0.878-0.889 and 208Pb/206Pb = 2.136-2.160], which approach, and trend toward slightly less radiogenic Sr and Nd values than, the enriched mantle component of type 1 (EM1). This feature distinguishes the HLP rocks from anorogenic carbonatites worldwide. We consider that delaminated and recycled lower-crust material is the most probable source of the HLP carbonatites. This interpretation is supported by the following evidence:

(1) The North China block (NCB) hosts a world-class Mo mineralization belt, and its lower crust has a high Mo content (Gao et al., 1998);

(2) Subduction of oceanic crust beneath the NCB resulted in amalgamation between the Qinling and NCB in the Mesoproterozoic (Zhang et al., 2002);

(3) Fractionation of REE in the lower crust could explain HREE enrichment in magmas derived from mantle sources affected by crustal recycling.

Recycling of carbonated oceanic crust through deep mantle over 1 Ga (or longer) can produce an EM1-type carbonate reservoir. The HLP carbonatite emplacement at 221 Ma followed the collision between the SCB and Qinling. The NCB was underthrust by crustal material derived from the Qinling during the collision, contributing to thickening of the lower crust beneath the NCB and its conversion to dense eclogite. This process culminated in brittle delamination of the eclogitized material into the mantle and its metasomatic reworking. Involvement of recycled lower-crust material in magma generation explains an enriched HREE and Mo signature of the HLP carbonatite magma.

References

Gao, S., Luo, T.C., Zhang, B.R., et al., 1998. Geochimica et Cosmochimica Acta 62, 1959-1975.

Zhang, B.R., Gao, S., Zhang, H.F., 2002. The Geochemistry of the Qinling Orogenic Belt. Science Press, Beijing.

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The nature of the Mo-bearing carbonatitic fluids from Huanglongpu deposit, Shaanxi, China: Evidence from fluid inclusions and stable isotope research

Song Wenlei1, Xu Cheng1, Jindrich Kynicky2

1Department of Geology, Peking University, China; 2 Department of Geology and Pedology, Mendel University, Czech

We report new microthermometric data for primary and pseudosecondary fluid inclusions of calcite and quartz from the Huanglongpu deposit. The fluid inclusions can be divided into 7 types, namely pure vapour including H2O-enriched gases or CO2(V), aqueous(L), two-phase aqueous-carbonic(VL), three phase aqueous-carbonic (LLV), solid-bearing aqueous(LVS), and solid-bearing aqueous-carbonic(LLVS). Note that most of the solid phase commonly occurs in LLVS-type inclusions. According to the crystal habits and the analyses of microraman spectroscopy the transparent solid phase are halite, sylvite, calcite, anhydrite, K-feldspar and the opaque solid inclusions represents probably molybdenite and Pb-bearing minerals.

Th of the VL, VL and LLV are 147-425 ℃, 13.2-15.5 ℃and 247-308 ℃respectively.

Homogenization temperatures were not determined for LVS or LLVS. However, the nature of the trapped minerals and the phase behavior of inclusions indicate that original fluids must have had even higher concentrations of SO4

2-, CO32- besides NaCl and KCl than was

previously expected. The C and O isotopic data for rock-forming calcite from carbonatites has uniform

isotopic compositions with δ13C and δ18O values ranging from -6.36 to -6.90‰ and 7.22 to 9.19‰ respectively. Meanwhile, the absence of 18O-rich carbonates and consistently low δ18O values of quartz from the orebodies (8.8–10.2‰) also suggesting a magmatic origin. S isotopic data for sulphides and barite from Huanglongpu carbonatites show that different S-bearing minerals have different S isotopic compositions deviate from the meteoritic mean δ34S(0‰) due to the S isotopic fractionation between sulphides and sulfate. Molybdenite displays δ34S values from -6.69 to -7.68‰ (mean -7.27‰), galena and pyrite range from -8.87 to -10.54‰ (mean -9.86‰) and -6.55 to -7.15‰ (mean -6.9‰) respectively in addition with 4.61 to 5.12(mean 4.75‰) for Sr-bearing barite. It also has been estimated that the δ34SΣS

interval of the ore fluids is about 1-2‰, suggesting a mantle-derived source. We propose that the parental ore forming fluid of the Huanglongpu exhibit moderate to

high salinity, CO2-dominanted system enriched in Mo, Pb, S, REE, and other ions expelled from fractionated carbonatite magma of mantle source. The unique sulphide bearing carbonatites of Huanglongpu deposit rapidly crystallized from carbonatite magma and associated brines of high salinity in very low pressures of shallow level.

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The Importance of Trace-Element Analysis for Petrogenetic Studies and Mineral Exploration (as exemplified by carbonatites)

Ekaterina Reguir

UniversityofManitoba,WinnipegR3T2N2,Manitoba,Canada

The abundances and behavior of trace elements can be used to gain insights into the composition of magma sources and the physical processes involved in magma generation and evolution. In contrast to the voluminous bulk-rock trace-element data and major-element analyses of minerals from carbonatites available in the literature, there has been no systematic study focused on the trace-element characteristics of the most common constituents of these rocks. In this work, we examined the trace-element composition of silicate minerals and perovskite from from 24 carbonatite localities worldwide. Several key compositional differences between micas from carbonatites and kimberlites have been identified and were used to establish new criteria for discriminating between these rock types. Phlogopite from kimberlites has significantly higher levels of Cr, Ni and Co, but is depleted in Nb, Mn, Sr, Sc and Zr relative to micas from calcite carbonatites. The practical significance of these findings is in providing mineralogical criteria that can be applied to kimberlite exploration. Our work shows that the clinopyroxenes and amphiboles from carbonatites contain similar levels of tetravalent high-field-strength elements (Ti, Zr and Hf) and compatible transition elements (Cr, Co and Ni), which are typically below 40 ppm. However, amphiboles are capable of incorporating much higher concentrations of Sc, Sr, Ba, REE and Zn. This study also showed that the garnets from carbonatites are capable of incorporating high concentrations of V, REE, Y, as well as fairly large amounts of Cr, Nb, Zn, Hf, Ta and Sc. The abundances of Th and U did not exceed 60 ppm. In agreement with previously published studies, our data show that the lightest of the lanthanides are strongly incompatible in calcic garnets. The differences in trace element budget of garnets reflect the geochemical characteristics of their host rocks. For example, enrichment in HFSE is not observed in garnets from post-orogenic carbonatites, whereas garnets from carbonatites occurring in rift settings are commonly enriched in both, Nb and Zr. Trace-element study of perovskite from carbonatite and associated clinopyroxenite from the Afrikanda complex, Russia, showed that perovskites from the two rock types are very different. The carbonatitic perovskite contains significantly higher amounts of Na, Pb, REE, Zr, Hf, Th, U, and lower levels of Fe, Al and Ta relative to perovskite from the clinopyroxenite. We also calculated partition coefficients for selected elements using data for perovskite from volcanic alkali ultramafic rocks. These partition coefficients were used to estimate how the values of several indicator ratios in perovskite will change during magma evolution, and to prove that the two rock types are not related to one another by crystal fractionation. We also conducted the U-Pb geochronological study of perovskite from the two intrusive units, which yielded a very similar age of 372 ± 6 Ma. The 87Sr/86Sr ratios of perovskite from both rock types are also remarkably similar and fall within the range of the mantle values. Similar isotopic compositions and ages of perovskite from the two rocks can be explained by their derivation from the same magma by liquid immiscibility, or from the same isotopically equilibrated but mineralogically complex mantle source. To summarize, the detailed knowledge of trace-element chemistry of silicates and other volumetrically important minerals from carbonatites is essential in assessment of economic potential of their host rocks. Silicates, for example, may contribute significantly to the whole-rock Rb, Sr, Ba, REE, Zr and Hf budget and contain the bulk proportion of compatible lithophile elements (most importantly, Sc and V).

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Rare earth deposits associated with carbonatite complexes – where are the heavy rare earths?

Frances Wall(1), Sam Broom-Fendley (1,2), Vistorina do Cabo(3) and Emma Dowman (4)

(1) Camborne School of Mines, University of Exeter, United Kingdom f.wall@exeter.ac.uk(2) British Geological Survey, Keyworth, United

Kingdom, (3) Geological Survey of Namibia, Namibia (4) Kingston University, Kingston upon Thames, United Kingdom

Carbonatite-related ore deposits provide the World’s main sources of the rare earth elements (REE). Compared with other REE deposits they have the advantages of high grade and tonnage, combined with low thorium contents. Carbonatite-related deposits can be conveniently divided into two categories. The first,contains carbonatites where the REE minerals have formed during igneous emplacement and immediate reworking, often in a pegmatoid environment. These carbonatites have relatively little disturbance to their mantle isotopic characteristics, and are usually enriched in the light REE. Mountain Pass is a member of this category and perhaps the best candidate for a mainly magmatic REE-rich carbonatite.Many other carbonatites in this category contain pseudomorphs in which burbankite has been replaced by a polymineralic REE-rich assemblage. They occur in many complexes but most tend to be small. Examples subject to active exploration include Bear Lodge, USA, Wigu Hill, Tanzania and Kangankunde, Malawi. The second category contains carbonatites in which the REE have been concentrated by either hydrothermal reworking or weathering as a result of removal of soluble minerals such as carbonate. The fluids may be predominantly carbonatite derived (e.g. Fen, Norway) or much later and the result of subsequent metamorphism and metasomatic alteration (Bayan Obo) or weathering (Mt Weld). These deposits tend to be finer grained and often of more complex mineralogy. Carbonatite REE deposits contain mostly the light REE but it is the heavy rare earths (HREE: Eu-Lu and Y) that are more highly sought after at the moment because of their role in new and green technologies. HREE are predominantly extracted from ion-adsorption clays in China. These are small, low grade deposits. Increased government control, environmental legislation and local demand for REE in China have led to high prices and global concerns about the security of supply of the HREE. There is potential for HREE deposits associated with carbonatites. Targets include carbonatitessuch as Lofdal, Namibia, where carbonatite dykes contain xenotime-(Y) together with LREE minerals. The original chemistry of the carbonatite magma, coupled with late-stage magma and fluid evolution, seem to be controlling factors on the HREE mineral formation[1,2]. The Khibina carbonatite, Kola Peninsula, Russia, is an example of where early LREE carbonatites become increasingly HREE-enriched as magmas evolve to carbo-hydrothermal fluids[3]. Breccias around Songwe, Malawi show areas with high Y/La ratios within the matrix caused by narrow zones of xenotime enrichment. Fenite around Kangankunde and Chilwa Island also in Malawi has higher HREE:LREE ratios than the carbonatite[4]. In weathered complexes, such as at Mt Weld, Western Australia, changes in both HREE concentration and LREE:HREE ratios are observed, forming the HREE mineral churchite (YPO4.H2O)[5]. References:

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[1]Wall et al. (2008), Can Mineral, 46, 861. [2] Do Cabo et al. (2011), Mineral. Mag, 75 (3), 770. [3] Zaitsev et al. (1998), Mineral. Mag, 62

(2), 225. [4] Dowman et al. (2011), abstract, Fermor conference, London. [5] Lottermoser (1990), Lithos, 24, 151

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Olympic Dam supergiant U-Cu-Au-Ag deposit: towards a new genetic model

Vadim Kamenetsky1, Jocelyn McPhie1, Kathy Ehrig2, Sebastien Meffre1, Roland Maas3

1ARC Centre of Excellence in Ore Deposits and School of Earth Sciences, University of Tasmania, Hobart, Tasmania 7001，Australia2BHP

Billiton, 55 Grenfell Street, Adelaide, South Australia 5000, Australia3School of Earth Sciences, University of Melbourne, Victoria 3010,

Australia

Olympic Dam (OD) in South Australiais a supergiant Cu-U-Au-Ag ore deposit (~9 × 109 t) hosted by hematite-rich tectono-hydrothermal breccia within the Mesoproterozoic (ca. 1590 Ma) Roxby Downs (RD) granite, overlain by late Neoproterozoic sediments. OD is the world’s largest uranium deposit, and fourth largest in gold and copper it is also rich in rare earth elements, fluorine, and iron. Itwas discovered using an exploration model developed for sediment-hosted stratabound Cu deposits, and initially interpreted to be a variety of sediment-hosted mineralization. At present, most researchers favour a magmatic-hydrothermal genetic model that advocates origin of OD within a ca. 1590 Ma mafic maar-diatreme volcanic system that vented to the surface through the host granite,and supplied and drove mineralized fluids. Our study of the host succession is focused on understanding the age and geochemical characteristics of mafic/ultramafic rocks and bedded sedimentary facies within the OD breccia complex. The results, published so far, and the work in progress will be used to justify a new genetic model that includes the following points:

1. Numerous sources outside the immediate locality of the ore, for example, banded iron formations (Fe), evaporites (S, Ba, Cl, C), rhyolites and granites (U, REE, F) and mafic rocks (Cu, Au, Cr, Ni) contributed to the OD deposit;

2. Pre-mineralization storage occurred during extensive sedimentation (conglomerate, sandstone, mudstone, ironstone) in a topographic depression atthe intersection of regional faults on top of the unroofed RD granite;

3. The sedimentation was ca. 1200 Ma (Pb-Pb dating of diagenetic pyrite) and probably related to the Grenville events associated with the assembly of the supercontinent Rodinia;

4. The presence of low-Ti, high-Cr spinel as detrital grains and in picritic clasts in the sediments and picritic dykes intruding RD granite point to a broadly supra-subduction zone environment prior to sedimentation;

5. Fortuitously preserved bedded sedimentary units locally developed ore-grade concentration of Fe, U, Cu and REE minerals due gravitational accumulation, diagenetic processes and fluid circulation;

6. Re-activation of regional faults (NW-SE) and related rifting and magmatism may have caused the collapse of mineralised sediments and introduced basinal waters into the RD granite caused brecciation of the RD granite. One of such events coeval with the Rodinia break-up in this region was represented by low-Ti continental basalts of the regional Gairdner Dyke Swarm(U-Pb dating ca. 800 Ma);

7. Rifting and magma intrusions provided mechanical energy and heat for brecciation and chemical reactions. Hydrothermal circulation, affected both the host granite and sedimentary pile, was instrumental in further concentration of ore components, preconcentrated in the sediments;

8. The OD ore-forming fluid,owing to regional magmatic rocks, was uniquely F-rich and had exceptional capacity to transport diverse elements. Moreover, highly corrosive hydrofluoric acid contributed to hydrothermal breccia formation by dissolution that in turn increased permeability and accelerated the rate of fluid-rock interaction.

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Reprecipitation textures and REE redistribution in REE mineral associations

Daniel Harlov

Deutsches GeoForschungsZentrum, Telegrafenberg, D-14473 Potsdam FR Germany

The current role of REE- and actinide-bearing phosphate and silicate minerals as both geochronological markers and recorders of geochemical fluid processes is reviewed. The minerals covered include some of the more common REE- and actinide-bearing minerals found in high-grade rocks, e.g., apatite, monazite, xenotime, zircon, and garnet. The goal is to describe how these minerals react with various fluids under P-T conditions ranging from mid to lower crust and how these interactions affect their role as geochronometers. Fluid-aided alteration of these minerals is the result of a solid state coupled dissolution-reprecipitation process, which, while chemically altering the mineral, preserves the original shape and habit and, in many cases, the original crystallographic lattice of the mineral. During this process both major and trace elements can be either added or taken away from the mineral in a fluid-aided action that depends on the reactivity of the mineral with the fluid as well as on the solubility of the element (in question) in the fluid.

In the case of apatite, fluids such as KCl brines, H2O, HCl, and H2SO4 will cause the inherent Y+REE component in the apatite to become mobile and form inclusions of monazite and xenotime via coupled dissolution-reprecipitation. Thorium will also be mobilized and incorporated in these inclusions. Monazite and xenotime are highly reactive in akali-bearing systems (Na2Si2O5+H2O, NaOH, NaF+H2O, KOH) with extensive Th, U, Pb, and (Y+REE) mobility. Solid-state coupled dissolution reprecipitation allows for either the incoporation or depletion of Th, U, and Pb in the altered areas. In certain cases this results in the inherent Pb being totally removed from these areas resulting in a complete resetting of the monazite or xenotime geochronometer thereby allowing these two minerals to effectively date metasomatic events.

Similarly zircon is highly reactive in alkali-bearing fluids (Na2Si2O5+H2O; NaF+H2O; NaOH) as well as alkaline-bearing fluids (Ca(OH)2; CaCl2 brines). Both sets of fluids allow for high Th, U, Pb, and (Y+HREE) mobility such that altered areas in the zircon are effectively reset with all the Pb removed to below the detectability limit of SIMS.

Lastly in the case of garnet, high pH solutions, such as NaOH, promote the partial, solid state alteration of garnet allowing for Y, Eu, and Sm to be incorporated in the altered areas, again via the mechanism of coupled dissolution-repreciptation.

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Destabilization of REE-bearing minerals under rock-fluid interaction conditions

Martin Ondrejka and Pavel Uher Dept. of Mineralogy and Petrology, Faculty of Nat. Sciences, Comenius University, Mlynská dolina; 842 15 Bratislava, Slovak Republic

REE-Y bearing accessory minerals (monazite, xenotime, allanite and apatite) are some of the most widespread accessory phases in common granitic and metamorphic rocks. These minerals

can be unstable under fluid-rich conditions and variable breakdown products can be formed depending on

the fluid composition. The most widespread breakdown products of monazite include apatite (often REE-rich), the ThSiO4 phase (huttonite or thorite), and allanite-(Ce) to REE-rich epidote or clinozoisite which commonly form concentric corona-like textures around a partly dissolved monazite core. Occasionally, bastnäsite- or synchysite-group minerals originated as replacement products of monazite, or allanite. Monazite dissolution and breakdown depend strongly on local mineral compositions, on P–T conditions and on the character of pervasive hydrothermal/metamorphic fluids, so more complex and variegated breakdown products can originate in specific conditions. The breakdown of metamorphic monazite-(Ce) from the Veľký Zelený Potok orthogneiss (Western Carpathians, Slovakia) resulted in two principal stages and coronal textures. The (1a) sub-stage represents the least abundant microtexture with a relic monazite surrounded by apatite–ThSiO4–allanite–clinozoisite corona. The apatites form polygonal grains with small inclusions (≤2 μm) of a ThSiO4 phase, and they are further overgrown by epitaxial allanite-(Ce) to clinozoisite. The most frequent (1b) sub-stage represents a more developed alteration stage and completion of reactions in the (1a) sub-stage, but it does not include any residual monazite in the central part of the coronas. This is a complete monazite replacement by apatite+ThSiO4 phase, while external parts are filled with allanite to clinozoisite. (2) The most progressive stage of the monazite breakdown is represented by the presence of the REE carbonate [hydroxylbastnäsite-(Ce)], which partly replaces the apatite+ThSiO4 phase and also overgrows the allanite-(Ce) to clinozoisite zone. The monazite breakdown was initiated by fluid sources differing in composition. Stage (1) originated due to post-magmatic hydrothermal fluids, whereas stage (2) indicates an input of younger, CO2-bearing metamorphic-hydrothermal fluids. Another example of REE-phosphate decomposition represents the replacement of primary magmatic monazite-(Ce) and xenotime-(Y) during post-magmatic alteration of the host rock by As-S-Sr-rich and high fO2 fluids. This specific fluid composition led to the formation of a unique complex REE phosphate–arsenate (monazite-gasparite; xenotime-chernovite) solid solutions (Tisovec-Rejkovo A-type rhyolite, Western Carpathians, Slovakia) or to an extremely S, Sr-rich monazite-(Ce) with the highest S content reported in nature (ca. 12 wt. % SO3, Bacúch magnetite deposits, Western Carpathians, Slovakia). This composition indicates a (Ca,Sr)S(REE,Y)–1P–1 substitution as a dominant mechanism of Sr and S entry into the monazite structure. Also primary magmatic accessory fluorapatite and allanite-(Ce) can be affected by breakdown phenomena to producing a unique assemblage of britholite group minerals including britholite-(Y), fluorbritholite-(Y), fluorcalciobritholite and its hydroxyl-dominant analogue (“calciobritholite”) as well as REE carbonates [bastnäsite-(Ce), synchysite-(Ce)], secondary monazite-(Ce), chlorite, epidote, and calcite in A-type granitic rock (Permian granite boulder incorporated in Cretaceous flysch sequence, of the Pieniny Klippen Belt, Western Carpathians, Slovakia). These textural and compositional data indicate extensive replacement and breakdown of primary magmatic REE,Y-bearing phases by subsolidus H2O-, CO2- and F-rich

17

fluids, deliberated during post-magmatic overprint of the host granite.

18

The REE-Ti-Nb-Ta oxide minerals: from crystal chemistry to ore deposits

Pavel Uher and Martin Ondrejka Dept. of Min. and Petrology, Faculty of Nat. Sciences, Comenius University, Mlynská dolina; 842 15 Bratislava, Slovak Republic

The REE-Ti-Nb-Ta oxide minerals forms a relatively variable assemblage of complex rare-element phases, containing both trivalent rare-earth elements (REE + Y), and Ti4+, Nb5+ and Ta5+ cations, as main mineral constituents. Two general formulae types could be recognized in the REE-Ti-Nb-Ta oxide minerals, where A = REE3+, Y3+ (Ca2+, Fe2+,3+, Th4+, U4+), and B = Ti4+, Nb5+, Ta5+ (Fe2+,3+, Zr4+) cations: (1) ABO4 type: samarskite, fergusonite and fergusonite-beta groups, and (2) AB2(O,OH)6 type: aeschynite and euxenite groups. High REE, Y, Ti, Nb and Ta contents show also some members of pyrochlore and perovskite group minerals but the both contain also important amount of alkali metals (Na+, Ca2+). Structural arrangement of the REE-Ti-Nb-Ta oxide minerals comprises various combinations of octahedral BO6 and polyhedral AO8 groups, formed usually chain or framework structure. Only fergusonite group members form insular BO4 tetrahedra connected into a framework by the 8-coordinated REE + Y cations in scheelite-type structure. Among the REE`s, the only Y (+ Yb in samarskite) dominant mineral species are known in samarskite and euxenite groups, whereas both Y and LREE (Ce and Nd) dominant members are present in the aeschynite, fergusonite and fergusonite-beta groups, e.g. aeschynite-(Y), -(Ce) and -(Nd); fergusonite-beta-(Y), -(Ce), and -(Nd). The Nb-dominant members are the most common B-cation in the all groups, Ti-dominant species are typical for the aeschynite and euxenite groups [e.g., aeschynites, polycrase-(Y), yttrocrasite-(Y),] and Ta-prevailing minerals occur in samarskite, aeschynite and euxenite groups [yttrotantalite-(Y), tantalaeschynite-(Y), and tanteuxenite-(Y)]. Due to analogous stoichiometry and composition between the ABO4 and AB2(O,OH)6 members and their common metamict state, it is difficult to classify the species; the compositional classification based on a statistical approach is used. The REE-Ti-Nb-Ta oxide minerals occur in the following endogenous environments: (1) Alkaline plutonic rocks: A-type granites and syenites, (2) Pegmatites of A-type granites (NYF family), syenite and nepheline syenite pegmatites, (3) Carbonatites: calcite and dolomite carbonatites, (4) Metamorphic, hydrothermal-metamorphic and metasomatic assemblages (veins, replacement zones, Alpine-type fissures). The above mentioned environments are usually REE + Y, Nb (Ti) rich, and Ta-poor, producing a dominant Nb,Ti-rich members. Only rarely, Ta>Nb,Ti species occur exclusively in more fractionated granitic pegmatites. On the other hand, the LREE (Ce and Nd) dominant members are known from specific parental rocks, mainly carbonatites and some hydrothermal- metamorphic deposits (for example Bayan-Obo). The REE-Ti-Nb-Ta oxide minerals occur commonly as disseminated minerals and their economic concentrations are generally not widespread, with exception of some NYF granitic pegmatites (e.g., Scandinavian region, Western Australia). On the contrary, accessory fergusonite-(beta)-(Y) and polycrase-(Y) are widespread phases in some A-type granites and they could represent a potential source of the rare elements in future.

19

Experimental data on element partitioning between immiscible silicate and carbonate

liquids with implications for the origin of rare metal deposits in carbonatites and

alkaline rocks

Ilya V. Veksler GFZ German Research centre for Geosciences, Telegrafenberg, Potsdam14473, Germany, e-mail: veksler@gfz-potsdam.de

There has been a significant progress in recent years in experimental studies of element partitioning between immiscible silicate and carbonatite liquids thanks to the works carried out in Switzerland (Martin et al., 2012) and Germany (Veksler et al., 2012). The progress has been mostly due to the employment of novel in situ centrifugation techniques using unique rotating internally heated pressure vessel and piston-cylinder apparatus. The experiments at pressures from 0.1 to 1.7 GPa covered a broad spectrum of liquid compositions from K-rich kamafugitic to analogues of natural natrocarbonatite. Carbonatite-silicate liquid-liquid Nernst partition coefficients representing weight concentration ratios D = Ccarb/Csil are now available for all the geochemically important groups of elements including rare earths (REE) and high field strength elements (HFSE) Nb and Zr, which are known to form economic ore deposits in alkaline-carbonatitic igneous complexes. The studies confirmed a general conclusion from previous experiments that the capacity of carbonatite melts to extract and concentrate metal cations is low. Depending on the bulk melt composition, the D values of light REE carbonate-silicate immiscible liquid systems usually vary around unity, and go further down for heavy REE, which tend to concentrate in silicate liquids. With the exception of Mo, W and P, all the other HFSE strongly concentrate in silicate liquids, and the lowest D values are those of Zr and Hf. The additions of H2O appear to slightly decrease the D values of alkalis and alkaline earths but the greatest, orders of magnitude effects are observed for Zr, Hf, Nb Al and Si. Although the D values of those elements still remain below 1, the solubilities in carbonatitic melts appear to dramatically increase in the presence of H2O.

New experimental constraints on the carbonate/silicate liquid-liquid D values confirm that carbonatites hosting economic rare metal mineralization of Nb, Zr, REE, Th and U are unlikely to form by liquid immiscibility. Such mineralized carbonatites may however result from extensive fractional crystallization of a carbonated nephelinitic parental magma. Immiscible carbonatites strongly enriched in SO3 and F may also have high concentrations of REE and HFSE, but such compositions have not been studied experimentally yet.

References

Martin L.H.J., Schmidt M.W. Mattsson H.B., Ulmer P., Hametner K. and Günther D. (2012) Element partitioning between immiscible

carbonatite–kamafugite melts with application to the Italian ultrapotassic suite. Chemical Geology, 320-321: 96–112.

Veksler I.V., Dorfman A.M., Dulski P., Kamenetsky V.S., Danyushevsky L.V., Jeffries T. and Dingwell D.B. (2012) Partitioning of elements

between silicate melt and immiscible fluoride, chloride, carbonate, phosphate and sulfate melts with implications to the origin of

natrocarbonatite. Geochimica et Cosmochimica Acta, 79: 20-40.

20

Sr- and REE carbonatite deposits of West Transbaikalia, Russia

German Ripp, Anna Doroshkevich, Evgeny Lastochkin, Ivan Izbrodin Geological Institute of SB RAS, Russia

There are two carbonatite provinces in the West Transbaikalia: one located in its northern part and formed in the Neoproterozoic (600-625 Ma), and the other located in a Late Mesozoic rifting zone in the southern part and formed around 130-118 Ma. The Neoproterozoic carbonatites of the northern part (Pogranichnoe, Veseloe) are dolomitic and represented by dykes up to 100 m in width and up to 1 km in length. They are not associated with any silicate rocks. The Pogranichnoe carbonatites are enriched in apatite (5-8 %) and magnetite and also contain aegirine and alkali amphibole. The carbonatites contain 1.5-3.5 wt.% SrO and 0.5-1.5 wt.% REE. The Sr enrichment is reflected in the compositions of dolomite, calcite and apatite. The carbonate minerals contain from 1.5 to 4.7 wt.% SrO, on average about 3 wt.%. Apatite contains from 3 to 6 wt.% of SrO, on average about 5 wt.%. The REE are mostly concentrated in apatite (1.5-3 wt.% REE2O3). Some amount of light REE is concentrated in monazite. One interesting observation is similar concentrations of Nd and La, and Th enrichment in the apatite (4-11 wt.% ThO2).The Late Mesozoic carbonatites of the southern part are represented by two types of rocks: those enriched in Sr (up to 20 wt.% SrO at Khaluta) and those enriched in REE (up to 9 wt.% at Arshan, Ulan-Udenskoe and Yuzhnoe). The carbonatites form dykes, shield-shaped bodies and pipes, which were formed under subvolcanic conditions. These rocks are associated with shonkinites and alkali syenites. The largest Sr deposit is Khaluta (1-20 wt.% SrO), comprising a number of dykes and shield-shaped bodies up to 100 m in width. The carbonatites are calcite rocks with apatite, magnetite and phlogopite. The Sr enrichment is reflected in the presence of barite-celestine and strontianite. The barite-celestine is a magmatic mineral and forms lenticular and laminated assemblages. The carbonatite bodies are selectively enriched in barite-celestine (and consequently, SrO) at the bottom due to gravitational process. Hydrothermal processes are the cause of intensive recrystallization of the carbonatites with precipitation of strontianite. Strontianite occurs as veins distributed irregularly within the carbonatite bodies and country rocks. The Arshan carbonatites form a REE deposit exposed as three shield-shaped bodies that range from 3 to 6 m in thickness. The rocks exhibit banded, sometimes brecciated, textures and contain xenoliths of country rocks. Calcite is the most abundant mineral, forming up to 60–80 % by volume. Sulfates of Ba and Sr and fluorite are also common minerals in the carbonatites; their content ranges between 10 and 12 % and as much as 7 %, respectively. The content of bastnäsite varies from 3 to 6 %. Bastnäsite occurs as tabular phenocrysts up to 2–3 cm across and as lenses 1-2 cm wide and over 10 cm long aligned parallel to the banded texture of the rock. The carbonatites contain 0.1-7 wt.% SrO and 1.5-9 wt.% REE. The REE content of the carbonatites reflects the presence of bastnäsite and, to a lesser degree, parisite, allanite-(Ce) and monazite. The major source of Sr is barite-celestine.

The research was supported by RFFR (11-05-00324) and Integral projects of RAS (ONZ 10.3) and (SB RAS 47).

21

Submarine Carbonatite Lava Genesis of the Bayan Obo Nb-REE-Fe Deposit, Inner Mongolia

Fei Hongcaia, * and Xiao Ronggeb a Chinese Academy of Geological Sciences, Beijing 100037 email: feihongcai@163.com bChinaUniversity of Geosciencs, Beijing 100083

Bayan Obo Nb-REE-Fe deposit is the world’s largest rare earth deposit, but its genesis is controversial, mainly due to the uncertain origin of dolomite unit H8. Discovery of carbonatite dykes provided direct evidence for carbonatite connection. Controversy still exists regarding the mode of carbonatite emplacement(intrusive vs. extrusive). Some workers argue that carbonatite magma intruded layers of H7 quartzite and H9 slate, whereas others suggest that carbonatite lava extruded under seawater. Carbonatites are intrusive or extrusive igneous rocks consisting of >50 modal % of carbonate minerals, and<20 wt.% SiO2. Carbonatites can be often confused with marble, which caused some misinterpretation of the ore-host rock in the Bayan Obo deposit. Previous geochemical studies of the dolomite marble show that it is composed mainly (70-90%) of dolomite and ankerite. Apatite and quartz, which are rarely present in sedimentary carbonate, are widely present in the dolomitic marble, and this is characteristic of carbonatite (Yang et al., 1998). The dolomitic marble, K-slate, Na-rich and carbonatite dykes have similar REE distribution patterns, characterized by strong REE enrichment and fractionation between heavy and light REE. Previous Sr, O and C isotopic studies suggest an igneous carbonate origin, indicating that the dolomite formed not only in an enclosed or a semi-enclosed basin, but was also affected by assimilation/contamination and hydrothermal reworking. Carbonatites commonly occur in rift environments, such as the East African Rift, although some carbonatites have been found in orogenic belts as well. The Bayan Obo deposit formed in a rift settings in the northern margin of the North China Platform. The H8 dolomite occurs as sheets, pipes and veins with strong liquation and flow structures, which is in accord with the study of Woolley and Church (2005), who identified that about one-half of extrusive carbonatites appear to occuras tephra cones, tuff rings, diatremes and maars, while the rest occur within stratovolcanoes. Breccia, shattered rocks and conglomerate found in the eastern part of the Main and East orebodies exhibit distinguishing features of extrusive carbonatite. A geothermometric study of calcite-dolomite pairs by Wang et al. (2010) shows that most carbonatites formed at a temperature of 400-500°C, similar to 500-600°Creported for volcanic carbonatites from Tanzania. The difference probably results from the effect of seawater on the extrusive rock, which is further supported by high δ18O and δ34S values, suggesting isotopic exchange between the rock and seawater. These data provide further evidence for a submarine volcanic origin of carbonatites at the Bayan Obo deposit.

22

REE deposits of Mongolia

Jindrich Kynicky1，Anton Chakhmouradian2, Ekaterina Reguir2,Cheng Xu3，Ulf Kempe4，

David Juricka1, Rene Kizek1, Hana Cihlarova1, Martin Brtnicky1

1 Mendel University in Brno, Zemedelska 3, 613 00 Brno 2University of Manitoba, Winnipeg R3T 2N2, Manitoba, Canada 3Peking

University, Beijing 100871, China 4Institut für Mineralogie, Bergakademie Freiberg, Brennhausgasse 14, 09596 Freiberg, Germany

A complete suite of rare earth element (REE) deposits in Mongolia; namely carbonatite related REE deposits (Mushgai Khudag, Bayan Khushu, Cogt Obo, Ulugei Khid, Lugiin Gol, Omnot Olgii, Khurimt Khuduck and others), peralkaline granite related Zr-Nb-REE deposits and occurrences (Khaldzan Buregtei and Khan Bogd) and metasomatic REE deposits (Bomin Khara, Gzarta Hudag); is evaluated by current research. Deposits and occurrences with carbonatite affinity: Allstudied deposits are associated with Mesozoic alkaline and carbonatitic rocksof rift related structures and large fold belts. REE deposits along Main Mongolian Lineament are typical by dominant fluorite and REE fluorcarbonate mineralization (up to 18 modal %). Phosphates (LREE rich apatite and monazite) belong to economic REE minerals too. Synchysite and parisite are principal REE ores for deposits ofGobi-Tien Shan Belt. Deposits and occurrences with affinity to peralkaline granites: Econimic REE and Zr-Nb-Hf mineralization occurs as finely disseminated, brecciated, massive texture. Rare earth and rare metal minerals can account up to 25 modal % in the case of Khaldzan Buregtei deposit. Minerals of economic significance are bastnaesite and synchysite (REE+Y) and pyrochlore (Nb, Ta, Ce, La,..). The average contents of major components are: 0.15-1.8% RE2O3, up to 0.04% Ta2O5, 0.05-1.17% Nb2O5. Main differences among rare earth element (REE) deposits in Mongolia: Chondrite-normalized whole-rock REE profiles exhibit a steep negative slope and lack detectable anomalies in the case of most carbonatite related REE deposits, while both peralkaline granite and related metasomatic REE deposits display clear enrichment in heavy REE and a negative Eu anomaly. The REE minerals show enrichment in LREE [(La/Nd)n=0.9-3.5]. In this respect, the carbonatite-hosted REE mineralization differs from most of the REE minerals of metasomatic and peralkaline granite related deposits, where the (La/Nd)n ratios are more variable and lower. The REE distribution patterns of individual REE minerals are similar, with the exception of Khaldzan Buregtei and Khan Bogd, where REE mineralization is associated with Zr mineralization and REE+Ycarbonates. At these two complexes, whole-rock and mineral-specific REE patterns are broadly similar, but Khaldzan Buregtei shows higher enrichment in HREE. The high-grade carbonatite related REE deposits at Lugin Gol, Omont Olgii or Khurimt Khuduck have a definite potential as a viable REE resource. Other deposits in Mongolia (e.g. Mushgai Khudag and Khaldzan Buregtei) have an economic value owing to their overall high grade, size and a healthy global REE market.The first papers on REE have been published; however, communicative and clear work is still missing although the economic high grade mineralization of REE deposits in Mongolia actually may play an important role in REE mining and production necessary for world demand.

23

The genesis of Zr-Nb-REE mineralisation at Khalzan Buregte (NW Mongolia) reconsidered

Ulf Kempe1, Robert Möckel1,5, Jindrich Kynicky2, Torsten Graupner3, Enchbat Dombon4 1Institut für Mineralogie, TU Bergakademie Freiberg, Brennhausgasse 14, 09596 Freiberg, Germany2Mendel University in Brno, Zemědělská

3, 613 00 Brno, Czech Republic3Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), Stilleweg 2, 30655 Hannover,

Germany4Department of Sciences, Technology, and Innovation, Mongolian University of Sciences and Technology, P.O. Box 520,

Ulaanbatar 46, Mongolia5Helmholtz-Institut für Ressourcen technologie Freiberg, Halsbrücker Str. 32, 09599 Freiberg, Germany

Presently known occurrences of Zr-Nb-REE mineralisation in the Haan-Hohiy-Hovsgol REE zone of northwest Mongolia concentrate around the Khalzan Buregte deposit located 45 km to the northeast of the town of Khovd, which is the capital of the Khovd aimak. Some smaller prospects including the better explored Ulaan Tolgoi and Shar Tolgoi occurrences are located further north, adjacent to the lake Khyargas nuur. The genesis of the Zr-Nb-REE mineralization in this area is a matter of debates. Kovalenko and co-workers studied Khalzan Buregte for several decades (Kovalenko et al. 1985, 1995, 2009a, b) based on a purely magmatic concept. However, no consistent interpretation could be reached. In contrast, Andreev and co-workers (Andreev et al. 1994, 1996) favoured an exceptional hydrothermal genesis of the mineralisation. In the present work, the genesis of the Zr-Nb-REE mineralisation is evaluated considering both, magmatic and hydrothermal processes of HFSE accumulation. Magmatic processes led to an enrichment of Zr, Hf, Nb, Ta, and REE up to sub-economic levels. Ore bodies are related to metasomatic alteration assemblages indicating a significant role of fluorine and carbonate complexes in the solutions. The exceptional high enrichment of heavy REE and Y in the ores is restricted to hydrothermally altered rocks. References:

Andreev G.V. Ripp G.S. Sharakshinov A.O. Minin A.D. Rare-metal mineralization in

alkaline granitoids of Western Mongolia. BNTS SO RAN, Ulan Ude 1994, 137 pp. (in Russian).

Andreev G.V. Ripp G.S. Rare-metal epidote-quartz metasomatites of the Khaldzan Buregteg massif.Zapiski Vsesoyznogo Mineralogicheskogo

Obshchestva 125, 1996, 24-30 (in Russian).

Kovalenko, V.I. Goreglyad A.V. Tsaryeva G.M. Khadzan Buregtey massif – a new manifestation of rare-metal peralkaline granitoids of MPR.

Doklady Akademii Nauk SSSR 280, 1985, 954-959 (in Russian).

Kovalenko V.I. Kozlovskij A.M. Yarmolyuk V.V. Trace element ratios as a reflection of sources mixing and differentiation of magma forming

alkaline granitoids and basitic rocks of the Khaldzan Buregtei massif and rare-metal deposit, western Mongolia.Petrologija 17(2), 2009, 175-

196 (in Russian).

Kovalenko V.I. Tsaryeva G.M. Goreglyad A.V. Yarmolyuk V.V. Troitsky V.A. The peralkaline granite-related Khaldzan-Buregtey rare metal (Zr,

Nb, REE) deposit, Western Mongolia. Economic Geology 90, 1995, 530-547.

Kovalenko V.I. Yarmolyuk V.V. Kovatch V.P. Kovalenko D.V. Kozlovskij A.M. Andreeva I.A. Kotov A.B. Sal´nikova E.B. Variations in isotope

composition and of critical ratios of incompatible trace elements as reflection of source mixing for alkaline granitoids and basites from the

Khaldzan Buregtey massif and of the rare-metal deposit there, Western Mongolia. Petrologija 17(3), 2009, 249-275 (in Russian).

24

The genesis of ion adsorption type REE+Y deposits of Granitoids in Dingnan region,

Jiangxi Province, Southern China

Lize Wang1, Cheng Xu1, Martin Brtnicky2, Jindrich Kynicky2

1Department of Geology, Peking University, China; 2 Department of Geology and Pedology, Mendel University, Czech;

Ion adsorption type REE+Y deposits (so called REE clays) are a unique deposit type originated by lateritic weathering of predominantly feldspar rich rocks (the most frequently granites) with accessory content of both primary magmatic and secondary REE minerals. This deposit type was first described in southern China. Residual deposits represent very important source of high demand HREE (heavy rare earth elements)and has subsequently become a much sought-after deposit type in the whole of South Asia. Ion absorption type REE+Y deposits probably control the distribution of almost all worlds’ economic HREE resources. The most important and the largest deposits are located in the southern Chinese provinces. In 1962, one of the most important regions of residual deposit type was discovered in Jiangxi Province and many deposits are still under operation and REE-enriched residual clays are under chemical extraction of REE insitu. Actual research provides the first information about those relatively REE (LREE-Y) clays (mineralogy, REE and HFSE hosts and detailed geochemical analysis of weathered crusts and clays).Individual representative residual REE+Y deposits are spatially and genetically related to deeply weathered granitoids. Study of the genesis of REE clays is still in its infancy, but most authors agree that these deposits formed by lateric weathering of mainly acidic igneous rocks. The weathering process resulted in alteration of primary REE minerals and complete disintegration of rock-forming minerals except quartz. Residual REE-clays, however, developed only in morphologically predisposed areas where there is minimal erosion, resulting in the development of a massive layer of residual material, often reaching thicknesses of more than 10 m. The granitic protolith in Dingnan region contains a significant proportion of accessory minerals containing REE, which are substantially stable. These minerals include various REE fluorocarbonates (bastnäsite and synchysite) and phosphates (monazite and apatite, and xenotime). Most of these minerals do not outlast the extreme weathering processes of humid climates and are the source of REE for ion adsorption type REE+Y deposits in Dingnan region. Alongside the formation of secondary REE phases, significant amounts of particularly the REE (LREE+Y) are absorbed on to clay mineral surfaces. The two most important adsorption phenomena in clays are cation exchange on the layer surfaces and chemisorption of anions at the edge. REE absorbed on clay minerals are mobilized, fractionated and enriched during adsorption and desorption process. Absorption process is a key in the concentration of the REE as a result of the preferential sorption of cations with higher charge size ratios.

25

REE and Rare Metal Elements Mobility and Mineralization during Magmatic and Fluid Evolution in Alkaline Granite System: Evidence from In-Situ LA-ICP-MS Study of Melt

Inclusions in Baerzhe Granite

Yi Sun，Yong Lai，Jing Chen and Qihai Shu

Key Laboratory of Orogen and Crust Evolution, School of Earth and Space Science, Peking University

Alkaline granite is commonly associated with REE and rare metal deposits. Previous works indicate that these elements are enriched in highly fractionated and volatile-rich residual magma and the late stage hydrothermal conditions. Unfortunately, the result from common petrology and geochemistry analysis may be affected by the strong fluid overprint process. Melt inclusions, which can preserve portions of primary melt, are the best samples to delve the mobility and mineralization of ore forming elements. In this study, we use in-situ LA-ICP-MS method to study the composition of melt and fluid-melt inclusions which trapped in quartz from Baerzhe Granite. Baerzhe granite contains the second large Be-Nb-Zr-REE deposit in northern China, and millions tons of RE2O3 and ZrO2, more than 10 thousand tons of Nb2O5 have been outlined. Baerzhe granite is hosted in alkaline granite (125 Ma) which intrudes in the late Jurassic Baiyingaolao Formation in the middle of the Great Hinggan Metallogenic Belt. The ore-forming granite consist three lithological facies: Arfvedsonite-bearing alkaline granite in the bottom, aegirine-bearing albite aplites in the middle and pegmatite crust on the top. The albite aplites are the main ore body. The main rare-mantel bearing mineral is columbite, zircon and pyrochlore which appear as the accessory minerals of granite and aplites. The REE-bearing mineral is bastnasite and xinganite, occuring as interstitial phases or secondary origin replacing the pre-forming mineral phases. We found melt inclusions in quartz from all of the three lithological faces. In pegmatite and albite aplites, the quartz also contains fluid-melt inclusions and primary fluid inclusions. The in-situ LA-ICP-MS analysis for single quartz-hosted melt inclusions and fluid-melt inclusions reveals the process of magmatic-hydrothermal evolution. It indicates that the primary magma evolutes to more peralkaline by fractional crystallization, with synchronously increasing high field strength elements. An extremely high contents of Zr and Nb are in the melt inclusions from last stage albite aplites (Zr, min 52548 ppm., and Nb, min 4104 ppm.). It implies that the residual magma can directly form the ore body of rare metal elements (mean, Nb2O5, 0.84% and ZrO2, 12%). Meanwhile, this study shows a reduction of Li, Be and REE in melt inclusions in albite aplites. It indicates that these elements were extracted from primary melt, and enriched in fluid phase. We also recognized that the whole rock composition has more obvious tetrad effect than the melt inclusions, and has wider range of Y/Ho ratio. These differences suggested that fluid overprinted on pre-crystalized granite. And this process may play an important role of REE mobility and deposition.

26

Geochemical and Sr-Nd-Hf-O isotopic constraints on the origin of the Neoproterozoic Qieganbulake ultramafic-carbonatite complex from Tarim Block, Northwest China

Hai-Min Ye1,2, Xian-Hua Li1*

1Institute of Geology and Geophysics, ChineseAcademy of Sciences, Beijing 100029, China2 Nanjing Institute of Geology and Mineral

Resources, China Geological Survey, Nanjing 210016, China

Neoproterozoic rift-related Qieganbulake ultramafic-carbonatite complex in the Northeastern margin of the Tarim Block, Northwest China, exhibits unusual Sr-Nd-Hf-O isotopic characteristics. The enriched signature of Sr-Nd-Hf isotope compositions of whole-rocksamples and minerals [(87Sr/86Sr)I =0.70570 to 0.70762, εNd(t) =-7.7to-12.5 and εHf(t)=-6.7to-12.9] indicates involvement of mantle metasomatism or assimilation of country rock. However, O isotope values of apatite from carbonatites (δ18O=6.02to6.13±0.14‰) show a primary magmatic signature (Taylor et al., 1967; Keller and Hoefs, 1995) consistent with a mantle origin and excluding the possibility of significant crustal contamination. The calculated depleted mantle model ages for Nd and Hf range from 1.6 Ga to 2.8 Ga, implying long-term storage of trace elements and isotopic enrichment of their sources in the subcontinental lithospheric mantle, rather than at depth within the convecting asthenosphere. The observed field relationships, geochronologic constraints and overlapping whole-rock and apatiteSr-Nd isotope compositions of diverse rock types reveal that their parental magmas were cogenetic. Trace-element variations in apatite from the carbonatites and clinopyroxenites show two independent trends, which are consistent with liquid immiscibility rather than crystal fractionation as the governing petrogenetic process.

Synthesis of Nd isotopic data for Neoproterozoic mafic-ultramafic rocks from the Tarim Block reported in recent years shows that these rocks exhibit a gradual increase in εNd(t) from North to South. Thus, we suggest that all mafic magmatism in the Tarim Block could be triggered by the arrival of the Rodinia mantle plume beneath the thick Archaean/Proterozoic lithosphere that had been metasomatised, and results fromthe mixing of meltsderived from the asthenospheric and subcontinental lithospheric mantle, with a gradual decrease in the proportion of asthenosphere-derived magmas from South to North. The northernmost Qieganbulake complex has nil to insignificant involvement of asthenospheric mantle component.

References

Keller, J., Hoefs, J. (1995). Stable isotope characteristics of recent natrocarbonatites from Oldoinyo Lengai. In: Bell, K., Keller, J. (eds)

Carbonatite Volcanism: Oldoinyo Lengai and the Petrogenesis of Natrocarbonatites. Berlin: Springer, 113-123.

Taylor, H.P., Frechen, C.H., Degens, E. T. (1967). Oxygen and carbon isotope studies of carbonatites from the Laacher See District, West

Germany and the Alnö District, Sweden. Geochimica et Cosmochimica Acta 31, 407-430.

27

Compositional variation and paragenesis of molybdenite in carbonatites from the Dashigou deposit in central China

Jindrich Kynicky1, Matej Medvecky2, Cheng Xu3, Anton Chakhmouradian4,Ekaterina Reguir4, Tomas Vaculovic2, Michaela Galiova Vasinova2, Wenlei Song3, Zeng Liang3, Hana Cihlarova1

1Mendel univerzity in Brno,Zemedelska3,61300Brno 2Department of Chemistry, Masaryk University, Kotlarska 2, 61137 Brno, Czech

Republic 3Peking University, Beijing 100871, China 4University of Manitoba, Winnipeg R3T2N2, Manitoba, Canada

The Dashigou deposit is one of the four main ore bodies of the Huanglongpu Mo-REE deposit cluster within the Qinling Mountains in Central China. The Qinling metalogenic belt (Mo, Au, Ag, Pb-Zn, W and Sb) hosts many important porphyry or porphyry- scarn type deposits except the Huanglongpu deposit that is the only Mo-REE deposit associated with carbonatites (Xu et al. 2009). Carbonatites of Dashigou deposit are represented by calcite carbonatites rich in several populations of sulfides and associated REE minerals. Modally the most widespread sulfide phase is coarse-grained pyrite, followed by galena, sphalerite and molybdenite. These minerals generally form euhedral to subhedral crystals and form crystals up to 400 mm in diameter in the case of pyrite and galena of pegmatite carbonatites. Molybdenite occurs as 4 distinct assemblages: (1) pyrite + molybdenite; (2) galena + molybdenite ± REE-bearing mineral; (3) very large pseudomorphs of molybdenite + pyrochlore after unknown mineral; (4) fine-grained molybdenite in tiny films along fractures and mineral grain boundaries. The Re content ranges from below the limits of detection in molybdenite of assemblages (3 and 4) to up to 0.1 wt.% in molybdenite of (2) and 0.1–0.4 wt.% in molybdenite (1). The Cu, Co, Ni, As, Se, Sb and Ag contents in the molybdenite are low (usually at or below the detection limits of WDS. Measurements by LA-ICP-MS revealed several interesting trace-element variations. The Cu content is generally higher in molybdenite from the carbonatites (6.6-10.2 ppm) than in pegmatitic carbonatite, where it is below the detection limit. Similar trends are observed for Ni and W values, but the relative variations are smaller. The Re, Nb and U are depleted in molybdenite from carbonatites.

References:

Cheng Xu, Jindrich Kynicky, Anton. R. Chakhmouradian, Liang Qi, Wenlei Song (2010): A unique Mo deposit associated with carbonatites

in the Qinling orogenic belt, central China, Lithos Volume 118, Issues 1–2, July 2010, Pages 50–60

28

Huanglongpu carbonatite related Mo-REE deposit: Unusual trace element content of

REE mineral associations

Hana Cihlarova1，Cheng Xu2，Anton Chakhmouradian3，MatejMedvecky4，Wenlei Song2,

Ekaterina Reguir3, Michaela Galiova Vasinova4，Zeng Liang2, Jindrich Kynicky 1

1 Mendel University in Brno, Zemedelska 3, 613 00 Brno2 Peking University, Beijing 100871, China3 University of Manitoba, Winnipeg R3T

2N2, Manitoba, Canada4Department of Chemistry,Masaryk University, Kotlarska 2, 61137Brno, Czech Republic

The Qinling metallogenic belt (Mo, Au, Ag, Pb, Zn, W and Sb) hosts many important porphyry and porphyry-skarn-type deposits, with the exception of the Huanglongpu deposit, which is the only Mo-REE deposit associated with carbonatites. This deposit lies in the Qinling orogenic belt forming the southern edge of the North China block. Individual ore bodies (up to 20500 m in size) extend discontinuously over a total distance of about 6 km. Carbonatite dykes consist mostly of calcite, K-feldspar, barite, pyrite, galena, sphalerite, molybdenite, apatite, britholite, REE fluorocarbonates, monazite, xenotime, allanite, and a range of other accessory minerals. The REE mineralization comprises several mineral associations that can be grouped into two paragenesis. Paragenesis 1 is enriched in light REE, whose relative proportions increase from the less widespread parisite-(Ce) [(La/Nd)n=1.1-2.0] to more abundant bastnäsite-(Ce) and the most widespread monazite-(Ce) [(La/Nd)n=1.7-2.2 and 2.3-4.5] usually closely associated with galena + molybdenite ± others REE-bearing minerals. Paragenesis 2 is enriched in heavy REE, whose relative proportion increase from xenotime [(La/Nd)n=0.2-0.6] to 4 populations of epidot group minerals with dominant allanite[(La/Nd)n=0.7-1.0] and Mn-REE allanite close to yttroallanite [(La/Nd)n=0.7-1.1]. The whole rock compositions are characterized by the highest Mo and heavy REE concentrations so far reported for carbonatites or any rock type worldwide: up to 3800 ppm Mo, 2650 ppm Y+(Gd…Lu) and (La/Nd)n= 1.0-2.6.

29

Some progresses for the study of Dalucao LREE deposit, Sichuan, SW China

Yan Liu Chinese Academy of Geological Sciences, China

Dalucao deposit, located at western Sichuan, SW China, is one of the large LREE giant deposits in the Himalayan Mianning- Dechang REE belt, which are associated with Cenozoic carbonatite- alkaline complexes that occur tectonically in the eastern Indo-Asian collision zone. Dalucao deposit is composed of No1, No2 and No3 deposits and No 1and No 3 is the main ones. Different with other REE deposits in the Mianning-Dechang REE belt, No1 and No3 deposits occurred in two breccia pipes respectively and the both pipes experience about four times cyptoexplosive beccia activities. Recently, some progress has been made on the wall-rock alternation, occurrence of weathering type orebody, types of REE minerals, mineral generations, mineral formation sequence and ore bodies’ formation ages. It was assumed that wall-rock alternation in Dalucao deposit is week in the past. In this study, the wall-rock alternation was proved very strong as syenite in the deposit turned into biotite-sericite rock bearing ore vines; orebody of weathering type is the main ore type and very popular in No 1 deposit with grade ranging from 5 to 60%; In Dalucao deposit, only bastnaesite REE mineral was reported. In this study, fine parisite, urdite, cerous carbonate, britholite crystals (less than 10µm) were found in oresunder microscope and BSE images (under 200-1000 times). Together with the field work, formation sequence of REE minerals and associate minerals was examined. 49Ar/43Ar dating of muscovite from ores in No1 (12.69± 0.13 Ma) and No3 (12.23± 0.21 Ma) deposits indicating they occurred at the same time. Despite both deposits have the same formation ages and geological setting, mineral compositions of ore types from both deposits are different: No 1 is characterized by fluorite-barite-calcite, while No 3 is characterized by celestite-calcite. It seems syenite contributes more to the No 1 than to the No3 considering lots of fluorite was found in ores from No1 and nearly no fluorite was found in ores from No3. Further examination is needed in the following time to test this assumption.

30

Geological and geochemical characteristics and genesis of “dolomite” at Bayan Obo,

China

Tiegeng Liu Chinese Academy of Sciences, China

Bayan Obo “dolomite” is distributed mainly at the south wing of the Kuangou anticline in

the northern margin of the North China Craton. It is not only host to world′s largest rare earth deposit but also parental rock for the large or very large niobium, iron, scandium and other minerals. The “dolomite” is not layered rock due to lacking no obvious bedding and fixed sequence, but a bedded dolomite belt with varying sizes. The “dolomite” has the obvious relationship of invasion with surrounding rock, which is reflected by the “dolomite” cutting through quartz sandstone (H4), slate (H5), and granite, and by many dolomite veins intruding the quartz sandstone (H4) and slate (H5). Residual cover phase of quartz sandstone (H4) occurs in the “dolomite”. Meanwhile xenoliths of quartz sandstone and slate were also found in the dolomite, along with strong alteration of country rocks. Biotitization of slate, riebeckitization of quartz sandstone, and alkaline metasomatism are very common in the mining area. The “dolomite” contains a large amount of mineral crystals such as niobium, rare earths, thorium, etc., which are common in igneous rocks. The sulfur, carbon, oxygen, strontium and iron isotope composition have deep source characteristics. All the features indicate that the dolomite is magmatic carbonate but not sedimentary carbonate.

31

Himalayan mountains and south Tibetan plateau: A larger reservoir for atmospheric

CO2

Yan Liu Chinese Academy of Geological Sciences, China

Global climate change has become one of the hottest issues worldwide. Knowledge of ancient Earth’s surface temperature is critical to understanding Earth today and in the future. Earth’s surface average temperature has decreased since the Eocene. It is generally accepted that this long-term global cooling is perhaps a consequence of long-term decreasing of global CO2 concentrations. However, it is still unknown where the huge atmospheric CO2 sinked. Since the Cretaceous, Indian plate has continuously flighted northwards, leading to the close of larger Neo-Tethyan Ocean and subsequent uplift of Himalayan Mountains and Tibetan plateau during the Cenozoic. A “Raymo” hypothesis that the uplift and erosion of the Himalayan-Tibetan orogen has drawn down atmospheric CO2 and cooled the globe is, therefore, present. However, this hypothesis has been recently challenged by the studies of degassing of hot springs within Himalayan Mountains. In this study, the role of Himalayan Mountains and south Tibetan plateau in the global carbon cycling is re-evaluated. During collision between Indian and Asian continents, the Himalayan Mountains have quickly uplifted and hence underwent stronger chemical weathering, leading to the formation of carbon-rich Siwalik formation within the north of Gange foreland basin to the south of Himalayan Mountains. The carbon-rich Siwalik formation, at the expense of huge atmospheric CO2, was subsequently transferred into the interior of Tibetan plateau, along with flat-subducted Indian crust. Some carbon from the buried Siwalik formation beneath Himalayan Mountains has been released back to atmosphere through hot-springs along Main Central Thrust system. Most buried carbon had, however, experienced (ultra)high temperature metamorphism along with silicates, and subsequently partial melting to form carbonic magmas beneath south Tibetan plateau. The huge atmospheric CO2 has, therefore, been transformed carbonic magmas, and then trapped within thickened crust of southern Tibetan plateau. This clearly suggests that Himalayan mountains and south Tibetan plateau are a huge reservoir for atmospheric CO2, accounting for the carbon sinking since the middle Miocene.

32

Equation of State for Carbonate liquids and Implications to Deep Earth Carbon Cycle

Qiong Liu1,2,3, Meili Wang1, Rebecca Lange2, Samuel Pottish3, Justin Wood3, Baosheng Li3, Toru Inoue4 and Cuiping Yang4 1 Key Laboratory of Orogenic Belts and Crustal Evolution, MOE; School of Earth and Space Sciences, Peking University, Beijing, 100871,

China2Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109-1005, USA3Mineral Physics Institute, Stony Brook

University, Stony Brook, NY 11794-2100, USA4Geodynamics Research Center, Ehime University, Matsuyama, 790-8577, Japan

An equation of state (EOS, P-V-T relation) for carbonate liquids is of considerable geological interest due to their high reactivity, low viscosity and thus high mobility, and close association with alkaline magmas. Furthermore, it can provide an assessment on the buoyancy and stability of carbonate liquids in the deep mantle. Fusion curve analysis is an effective way to determine the EOS of a liquid by comparison between phase equilibrium experiments on melting reaction of a mineral that melts congruently and the calculated melting reaction for that mineral obtained from thermodynamic properties. In this study, we experimentally determined the fusion curve of K2CO3 up to 11.5 GPa and compared our results with the calculated melting reaction. The requisite thermodynamic data needed to calculate the fusion curve are available from the literature, with the only unknown being the pressure dependence of the liquid compressibility, namely K’. Our results show that the slope (dP/dT) of the melting curve of K2CO3 remains positive up to 11.5 GPa. The derived liquid K’ values vary linearly with temperature between 13.2 – 20.5 at the pressure range of 1.9 – 11.5 GPa (based on use of the 3rd-order Birch-Murnaghan EOS). These data indicate that alkaline carbonate liquids are not stable at exceptionally low temperatures at high pressure and that they remain strongly buoyant relative to silicate melts in the deep mantle. These results also support the hypothesis that highly compressible liquids at one bar have correspondingly high K’ values (Lange, 2002).

33

Isotope Tracing of the Deep Carbon Cycle

Hongming Zhang1 , Shuguang Li2,1 1Science Research Institute, ChinaUniversity of Geosciences, Beijing, China2CAS Key Laboratory of Crust-Mantle Materials and

Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China

Deep carbon recycling is an essential part of the global carbon cycle. Carbonates at the seafloor are brought into the mantle by subduction. Subsequently, deep carbon is released to the atmosphere in the form of CO2 through volcanism. At present, research on deep carbon recycling is still at its early stage. The proportion of subduction-related carbon and primary mantle-derived carbon in CO2 released by volcanoes is an important issue. Carbon isotope studies can easily distinguish organic carbon from inorganic carbon. However, ~95% of subduction-related and primary mantle-derived carbon released by volcanoes is inorganic, whose sources are difficult to distinguish on the basis of C data. Recently, Ca and Mg isotope geochemistry has provided important tools for tracing recycled crust-derived material. Here, we focus on this topic by introducing the principles of C, Ca, and Mg isotopes in tracing deep carbon recycling and previous research results.

Carbon isotopes could easily distinguish organic and inorganic carbon because the δ13CPDBvalues of organic carbon are lower than –15‰, whereas those of inorganic carbon are higher than –10‰. If mantle-derived rocks or inclusions have δ13C lower than –15‰, their sources must contain abundant crustal material.

To understand the effect of the deep carbon recycling on CO2 in the atmosphere, an accurate estimation of the proportion of subduction-related carbon and primary mantle carbon must be done. Joint C-He isotope tracing is one of the ways to explore this issue. However, further work on this subject is needed.

Increasing attention has been given to newly developed Ca and Mg stable isotope systems with respect to using these isotopes for tracing crust-derived material cycling. A large amount of Ca and Mg is stored in carbon-rich oceanic sediments and basalts. The Ca-Mg isotopic composition of sediments is significantly different from that of the mantle. Thus, Ca-Mg isotopes may be used to trace subduction-related carbon in mantle-derived rocks, providing crucial evidence in solving some scientific issues. This research has made initial progress. Some of the issues that remain to be explored in detail are:

(1) Does the Mg isotopic composition of oceanic carbonate change with time?

(2) Do the Ca and Mg isotopes fractionate during the process of (ultra) high-pressure

metamorphism and dehydration?

(3) Do differences exist in Ca-Mg isotopic tracing under different geological conditions?

34

Liquid immiscibility in REE- and sulphate-rich silicate-carbonate magmas: examples of the Western

Transbaikalia carbonatites, Russia

Anna Doroshkevich1, German Ripp1, Ilya Veksler2, Andrey Borovikov3

1 Geological Institute of SB RAS, Russia2 GFZ German Research Centre for Geosciences, Germany3 V.S. Sobolev Institute of Geology and

Mineralogy , Russia

Late Mesozoic (130-126 Ma) carbonatites of the Western Transbaikalia (Arshan, Khaluta, Yuzhnoe) intruded along the margins of rift depressions and formed vein-like, tabular and shield-like bodies. Rocks associated with carbonatites are represented by potassic shonkinite and alkali syenite. The carbonatites are sövites strongly enriched in SO3 (up to 10 wt.%), rare earths (up to 7 wt.% total REE oxides) and fluorides (up to 6 wt.% F). It has been proposed that carbonatites of this type formed by liquid immiscibility between carbonate-sulphate and shonkinite-syenitic silicate magmas.

The origin of the sulphate-rich carbonatites in Western Transbaikalia by immiscibility is supported by spatial and temporal proximity of the carbonatites to alkaline silicate rocks, and by compositional similarities between minerals (e.g., phlogopite, calcite, apatite, magnetite and sulphates) in both rock types. The O and C isotopic compositions of the major minerals from the carbonatites and silicate rocks are similar and argue against carbonatites being residual products of fractional crystallisation of a single magma batch that crystallised silicate rocks first. Calcite and Ca, Ba and Sr sulphates are common daughter minerals in melt inclusions in pyroxene and titanite from shonkinite. Importantly, immiscibility between carbonate-sulphate and silicate liquids has been reproduced in heating experiments on the melt inclusions.

Carbonatite-shonkinite bulk rock concentration ratios of major components and trace elements are generally consistent with experimentally determined liquid-liquid partition coefficients. Significant inconsistencies have been identified only for Na, K and REE. The concentrations of Na and K in carbonatites (≤ 2 wt.% Na2O + K2O) are lower than expected for an immiscible carbonatite liquid in equilibrium with a conjugate silicate liquid having around 8.5 wt .% Na2O+K2O (as in shonkinite). The REE carbonatite-shonkinite enrichment factors are, on the other hand, higher than experimental partition coefficients between immiscible carbonatite and silicate liquids. The extensive development of fenites around carbonatite bodies and frequent occurrences of Na-K carbonates (nahcolite) and sulphates (tenardite, arcanite and aphthitalite) in daughter mineral assemblages of crystallised melt inclusions imply that the bulk rock alkali content of the sövite may be much lower than that of the parental carbonatitic liquid. Our estimations of the original total alkali content in the immiscible carbonatite liquid are up to 19 wt.% Na2O+K2O, in a good agreement with the experimental liquid-liquid partition coefficients. The apparent disagreement between the REE bulk rock enrichment factors and experimentally determined partition coefficients is harder to explain, and may require additional experimental data.

The present study was carried out with support from the RFFR (11-05-00324 and 12-05-00618).

35

The Belaya Zima Nb and REE carbonatite deposit, Russia

Anna Doroshkevich1, German Ripp1, Nikolay Vladykin2, Viktor Posokhov1

1 Geological Institute of SB RAS, Russia2 Vinogradov Institute of Geochemistry SB RAS, Russia

The Belaya Zima (BZ) carbonatite complex is one of the world’s largest sources of niobium and light rare earths. It is situated in the northern part of the East Sayan Mountains, Russia. The BZ is a multiphase central intrusion with elliptical exposure covering a surface area of about 18 km2, and concentrically zoned structure.with carbonatite intrusion in the center (an area of about 10 km2), surrounded by rings of alkaline silicate rocks. The complex comprises the following sequence of rocks from the earliest to the latest: pyroxenites-melteigite-ijolites, nepheline syenites surrounded by fenites, alnöites, carbonatites, with ankerite carbonatite post-dating calcite carbonatite (Pozharitskaya and Samoylov, 1972). According to the U–Th–Pb dating, nepheline syenites were emplaced at 643 Ma, but K/Ar dates of 543 Ma on phlogopite from calcite carbonatites imply a significant gap between alkaline and carbonatite intrusion (Yarmolyuk et al., 2005). Three major types of ores occur at BZ: Nb-Ta-P (calcite carbonatites with pyrochlore and apatite), REE-P (ankerite carbonatites with REE-fluorcarbonates and monazite) and Nb-REE-P (weathering crust on carbonatites). The mineral reserves are 103 million tons of Nb (the average grade of 0.27 wt.%), 60 million tons of REE oxides (at the average grade of 1.8 wt.%), and 7800 million tonnes of P (at the average grade of 4.6 wt.%) (Belov and Frolov, 2011). Nb, Zr and REE form 21 minerals, 7 of which are new species found for the first time at BZ. The main Nb mineral in carbonatites is pyrochlore including the U-pyrochlore variety. The Nb enrichment is also reflected in the presence of fersmite, columbite-(Fe), lueshite, latrappite, baotite, aeshenite-(Ce), zirkelite, calzirtite. The REE form bastnasite-(Ce), parisite-(Ce), synchysite-(Ce), ancylite-(Ce), burbankite, carbocernaite, rhabdophane-(Ce), monazite-(Ce) and Ta-laeschynite hosted mainly by ankerite carbonatites. Carbon and oxygen isotopic values for calcite from calcite carbonatites (δ18ОSMOW 6.91-7.37‰ and δ13CPDB (-5.65) – (-6.06 ‰) are similar to mantle-derived carbonates. The position of the values for dolomite and ankerite from ankerite carbonatites indicates Rayleigh isotope fractionation during magma crystallization (δ18ОSMOW 7.28-11.35‰ and δ13CPDB (-4.37) – (-5.58)‰).δ18ОSMOW in pyrochlore from calcite carbonatites varies from –0.10 to –7.44‰. Magnetite and apatite has higher δ18О values from 0.50 to 1.54 ‰ and from 1.95 to 2.50 ‰, accordingly. Oxygen isotope values for phlogopite from ijolites (3.34 ‰), calcite carbonatites (3.62-4.36 ‰) and ankerite carbonatites (4.41-4.61 ‰) indicate isotope fractionation during magma crystallization. Reaction with meteoric water is a possible explanation for the lower δ18ОSMOW in minerals relative to the mantle values. The order of isotopic enrichment of minerals in δ18ОSMOW (pyrochlore–magnetite–apatite–phlogopite–nepheline–calcite–ankerite) is in agreement with equilibrium fractionation at temperatures of 515-815°C. The magnetite-ilmenite pair yielded temperatures between 640°C and 685°C. The initial 87Sr/86Sr ratios of the calcite and ankerite carbonatites vary in the narrow range of 0.70294-0.70305 and 0.70303-0.70307, respectively. Both types of carbonatites are characterised by a wide range of 143Nd/144Nd from 0.51226 to 0.51246. The age-corrected values of the εNd (T640Ma) for the rocks are 3.51-4.57. Their Sr–Nd isotopic signatures indicate that the source of carbonatites was isotopically heterogen and moderately depleted.

36

The studies have been carried out with the support of the RFFR (11-05-00324).

References

Pozharitskaya L.K. and Samoylov V.S. 1972. Petrology, mineralogy and geochemistry of Eastern Siberia, Moscow: Nauka, 267 p (in

Russian)

Yarmolyuk V.V., Kovalenko V.I., Sal’nikova E.B., Nikiforov A.V., Kotov A.B., Vladykin N.V. 2005.

Late Riphean rifting and breakup of Laurasia: data on geochronological studies of ultramafic alkaline

complexes in the southern framing of the Siberian craton, Doklady Earth Sciences, 404 (7), 1031-1037

Belov S.V. and Frolov A.A. 2011. To a problem of industrial uranium-content in carbonatite deposits,

Otechestvennaya geologiya, 4, 24-35

37

A new type of Carius tube for the determination of Re-Os and PGE in geological

samples

Liang Qi State Key Lab of Ore Deposit Geochemistry, Institute of Geochemistry, ChineseAcademy of Sciences, Guiyang, China, 550002

e-mail: qilianghku@hotmail.com

The technique of Carius tube and high-pressure asher (HPA-S) is commonly employed for quantification of platinum-group elements (PGEs) and Re-Os isotopes in geological samples. They have low procedural blanks relative to other techniques for digesting geological samples. Using this technique, Re and all PGEs are in their highest oxidation state with complete equilibration between spikes and samples.

Up to date, previously used Carius tubes, essentially similar in shape to that reported in Shirey and Walker (1995), include a main body and a narrow neck. The glass walls between the main body and the neck are usually inhomogeneous because the neck has a smaller internal diameter(about 6 mm), such that it is difficult to make an evenly thick glass wall. Such inhomogeneity can easily result in rupturing of the Carius tube. Moreover, the sealing of a Carius tube is difficult and requires high-pressure steel bottles of oxygen and propane and a welding torch. Well trained and experienced technicians are essential for the application of this technique. Carius tubes are difficult to clean and thus normally used only once. In addition, it is difficult to transfer samples into the Carius tube.

The quartz tube for HPA-S is sealed by covering a PTFE tape and a piece of glass with high external pressure of nitrogen. Although it is very convenient to seal the quartz tube and the tube can be used repeatedly, the equipment is costly. Acids may escape and erode the instrument if samples contain carbonate, sulphide, or organic matter that can generate additional gas during sample digestion. Thus, it is required to design an alternative technique, such that the glass tube can be easily sealed and reused to allow for routine analysis of Re and Os isotopes.

In this study, we report a new type of Carius tube for digesting geological samples. This technique does not require sealing glass tubes using a high-temperature welding torch. The newly designed glass tube consists of the main body, neck and head. The main body has a 3 mm thick glass wall and 200 ml volume, whereas the neck and head have a glass wall 4 mmin thickness. This new tube type can be used repeatedly and easily sealed with a glass lined-PTFE stopper. We demonstrate that with our design, a temperature of 220 oC can be reachedand that digestion is as efficient as with the traditional technique. This new type of Carius tube significantly simplifies the sealing procedure and reduces the cost in comparison with the traditional Carius tube and can be used for routine analysis of Re-Os and PGE in geological samples.

38

Crystallization process of zircon and fergusonite during hydrothermal alteration in Nechalacho REE deposit, Thor Lake, Canada

Mihoko Hoshino1, Yasushi Watanabe1, Hiroyasu Murakami1, Yoshiaki Kon1 and Maiko Tsunematsu1

1 Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology (AIST), Central 7, Higashi

1-1-1, Tsukuba, Ibaraki, 305-8567, Japan

Two drill holes that penetrated sub-horizontal REE ore units at the Nechalacho REE deposit in the Proterozoic Thor Lake syenite, Canada, were studied in order to clarify the mechanism of enrichment in high-field-strength elements (HFSE = Zr, Nb) and REE. Zircon is the most common REE mineral in the ore units, and occurs as five distinct types. Type-1 zircon occurs as discrete grains in phlogopite, and is chemically similar to igneous zircon. Type-2 zircon consists of a porous core enriched in heavy REE (HREE) and a rim enriched in light REE (LREE), Nb and F. Fluorine enrichment in the rim of type-2 zircon suggests that F was related to the HFSE-REE enrichment. The core of type-2 is regarded to be magmatic and the rim to be hydrothermal in origin. Type-3 zircon occurs as euhedral to anhedral crystals, which occur in complex intergrowths with REE fluorocarbonates. Type-3 has high REE, Nb and F contents. Type-4 zircon consists of a porous core and rim of similar chemical composition. This zircon is subhedral and rimmed by fergusonite. Type-5 zircon is characterized by smaller, porous and subhedral to anhedral crystals. The interstices between small zircon grains are filled by fergusonite. Type-4 and -5 compositions have low REE, Nb and F contents. Type-1 is only found in one unit, which is not strongly hydrothermally altered or mineralized. Type-2 and -3 grains mainly occur in shallow units, while type-4 and -5 crystals are found in deep units. The deep units exhibit high HFSE and REE contents and strongly altered mineral textures in comparison with the shallow units. Occurrences of these five types of zircon are different according to the depth and degree of the hydrothermal alteration by F- and CO2-rich solutions. These variations allow a model for the evolution of the zircon crystallization in the Nechalacho deposit to be developed, as described below.

(1) Type-1 zircon is formed in syenite;

(2) LREE-Nb-F-rich hydrothermal zircon formed around HREE-rich magmatic zircon

(type-2);

(3) Type-3 zircon crystallized through the F and CO2-rich hydrothermal alteration of type-2,

which formed the complex intergrowth with REE fluorocarbonates;

(4) The CO2-rich hydrothermal fluid corroded type-3, forming REE-Nb-poor zircon (type-4).

Niobium and REE were no longer stable in the zircon structure and crystallized as

fergusonite around the REE-Nb-leached zircon (type-4);

(5) Type-5 zircon is formed by more CO2-rich hydrothermal alteration of type-4, suggested

by the fact that type-4 and type-5 grains are often included in ankerite.

Type-3 to -5 zircons at the Nechalacho REE deposit were continuously formed by leaching and/or dissolution of type-2 in the presence of a F- and/or CO2-rich hydrothermal fluid. REE and Nb in the fluid were finally concentrated into fergusonite by way of REE-Nb-F-rich zircon in the hydrothermally altered units.

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Hydrothermal process in REE enrichment and fractionation

Martin Smith School of Environment and Technology, University of Brighton, U.K.

Many carbonatite and alkaline igneous rock-related deposits of the REE and other critical metals are dominated by the light REE (LREE- La-Nd), whilst much economic interest is focused on the middle to heavy REE (M-HREE). In many examples processes whereby deposits become enriched in progressively heavier REE are controlled by processes in aqueous and aqueous-carbonic hydrothermal fluids of either orthomagmatic or externally derived origin, or by supergene weathering processes. Mineral-REE partitioning can be influenced by temperature and pressure, the composition, structure and crystal chemistry of the mineral phase, the chemistry of the fluid in terms of both major elements and ligand availability and complexation, the kinetics of mineral growth, fractional crystallisation processes and sorption on to mineral surfaces.

This presentation will take the example of the Bayan Obo Fe-REE-Nb deposit in order to examine the role of hydrothermal processes in the fractionation of the REE. The Bayan Obo Fe-REE-Nb deposit is the world’s largest economic REE deposit with reserves suggested to be in the range 600Mt iron oxides and in excess of 100Mt REE oxide at approximately 6wt. % REE2O3. The origin of the deposit is controversial with hypotheses including primary carbonatitic magmatic mineralisation through to hydrothermal mineralisation associated with ‘subduction derived fluids’. A full interpretation, integrating field and textural characteristics, geochemical evidence, geochronology and isotopic data is consistent with a multistage origin involving the metamorphism and subsequent hydrothermal modification during Caledonian times of an initial Proterozoic, carbonatite-related, hydrothermal REE accumulation. Textural studies show repeated episodes of overprinting REE mineralisation, but with consistent isotopic characteristics, suggesting repeated remobilisation of a single source. Niobium mineralisation, however, occurs overprinting foliation and in cross-cutting, undeformed, vein and vug space. This suggests a second, post deformation, phase of HFSE mineralisation, possibly related to additional input of fluid related to alkaline magmas. The chemistry of alteration phases also strongly indicates 1 phases of fenite-like alteration in the ore deposits.

Throughout the REE mineral paragenesis at Bayan Obo the REE patterns vary in a systematic manner. The properties of fluid inclusions also vary with paragenesis, indicating changing fluid conditions during the deposits formation. In early disseminated monazite and in the main stage banded ores, the chondrite normalised La/Nd ratio varies from 3 to 7, whilst vein-hosted bastnäsite and monazite show ratios in the range;4.8 to 5.8. The La-rich portion of this trend (La/Nd.4) is inferred to correlate with higher T and highX(CO2) in the hydrothermal fluid. Minerals with lower La/Nd ratios are inferred to have formed from dominantly aqueous solutions. This correlation is interpreted as arising from the greater retention of neutral species in low dielectric constant, CO2-rich fluids, relative to the dominantly aqueous fluids. At high T, high ligand number complexes of La are predicted to be more strongly associated than for the other REE, leading to the observed fractionation. The REE contents of Nb phases show similar variations, although in the banded ores aeschynite shows significant zonation in the content of the REE, Y, and Th. This is inferred to relate to buffering of halogen acid species to low levels by dissolution and fluoritisation of calcite, and the preferential precipitation of

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LREE from solution due to low mineral solubility products compared to the HREE.

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Postorogenic carbonatites and their significance for rare-metal exploration and geodynamic analysis

Anton R. Chakhmouradian Department of Geological Sciences, University of Manitoba, 125 Dysart Road, Winnipeg, Manitoba, Canada

Carbonatites are an extremely rare group of igneous rocks that have lately been “in the spotlight” owing to their enrichment in rare-earth elements (REE), the staple ingredient of many innovative and green technologies. Mineral exploration programs targeting these rocks routinely use geochemical criteria such as abundances of certain trace elements in bedrock, weathering profile and vegetation to discriminate between carbonatites and modally similar non-igneous rocks (e.g., hydrothermal carbonate veins, skarns and marbles). The recognition that carbonatitic magmas are a potent agent of mantle metasomatism, not restricted to a single tectonic setting, led to renewed interest in geochemistry of these magmas and its relation to mantle processes and tectonics. For example, interaction between carbonatitic melts and mantle rocks has been invoked to explain the unusual geochemical characteristics of certain silicate magmas from arc, back-arc, intracontinental rift and oceanic island settings. It has been increasingly recognized that carbonatites have multiple origins, which is reflected in their geochemical characteristics. However, these relations have not been systematically studied to date. In fact, a singleaverage composition based on a limited dataset has been used routinely for the identification of the possible products of carbonatitic magmatism or metasomatism. Our understanding of these economically important rocks lags significantly behind the progress made in other areas of igneous petrology (e.g., granitic and basaltic magmatism).

There were several attempts to systematize the geochemistry of carbonatites, notably by Samoilov (1984), Nelson et al. (1988), Woolley and Kempe (1989), and Rass (1998). These studies revealed a number of important geochemical characteristics that can be used to identify carbonatites and their associated mineral deposits. However, these studies had some significant shortcomings that limit their applicability for either academic or industrial purposes. A new representative dataset(~850 analyses of calcio-, magnesio- and ferrocarbonatites from 180 localities worldwide, excluding those of uncertain tectonic affinity) was used to distinguish two major types of continental carbonatites: (1) those emplaced in rifts and other extensional structures developed in cratons or ancient orogenic belts, and (2) those emplaced in postorogenic settings. In both cases, the most common and best-studied rock type is calcite carbonatite (over 60% of the data).

Historically, carbonatites related to orogenic processes (type 2) were not studied in as much detail as type 1, and in some cases, were simply overlooked due to their obscured exposure and superficial similarity to deformed metasedimentary rocks. Our recent and ongoing work in Manitoba and elsewhere in the world indicates that postorogenic carbonatites are emplaced in collision zones and active margins of continental plates shortly after the cessation of synorogenic granitic magmatism. Their mantle sources are distinct from those that produce anorogenic carbonatites, and their ascent is controlled by extensional structures related to orogenic processes. Postorogenic carbonatites are commonly associated with clinopyroxenites (grading to glimmerites), feldspathoid syenites (typically, K-rich) and oversaturated syenites of shoshonitic affinity. Type-2 carbonatites are notably different from their type-1

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counterparts in showing much lower abundances of high-field-strength elements (HFSE), but overall higher levels of REE, Sr and Ba. These rocks also differ in some trace-element ratios. The most probable source of postorogenic carbonatites is depleted mantle metasomatized by subduction-derived fluids depleted in HFSE, but enriched in light carbon.

The generally higher levels of REE in postorogenic carbonatites make them an attractive exploration target. However, prospecting for these rocks and their correct identification is complicated by the fact that their primary igneous texture is commonly erased to give way to a metamorphic texture that is a complex product of plastic flow, grain deformation, comminution, syn-deformational mineral reactions, post-deformational recovery, and hydrothermal reworking. These processes have profound implications for both grassroots exploration and resource evaluation. Another practically important aspect of carbonatites emplaced in tectonically active areas is subsolidus remobilization of REE that leads to changes in the distribution of these elements among the primary and secondary hosts, and fractionation within the REE series.

References

Nelson, D.R., Chivas, A.R., Chappell, B.V. and McCulloch, M.T. (1988) Geochemical and isotopic systematic in carbonatites and

implications for the evolution of ocean-island sources. Geochim. Cosmochim. Acta, 52, 1-17.

Rass, I.T. (1998) Geochemical features of carbonatite indicative of the composition, evolution, and differentiation of their mantle magmas.

Geochem. Int., 36, 107-116.

Samoilov, V.S. (1984) Geochemistry of Carbonatites. Nauka, Moscow (in Russ.).

Woolley, A.R. and Kempe, D.R.C. (1989) Carbonatites: nomenclature, average chemical compositions, and element distribution. In:

Carbonatites: Genesis and Evolution (K. Bell, Ed.). Unwin Hyman, London, 1-14.0

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Some Economic Factors to Consider in Mining and Processing Rare Earths

Clint Cox Anchor House, Chicago, United States of America

There are the most important economic factors to consider when mining and processing rare earths: 1. Mining Bringing rare earth elements (REE) to the market begins with mining. Costs for mining can vary widely depending on infrastructure (including roads, power, workforce, water and climate), land use issues affecting local stakeholders, grade and tonnage (which can be affected by recovery rates and elemental distribution), and by-product production. 2. Mineralogy The processing and economics for monazite, xenotime, bastnaesite, loparite, and ion adsorption clays are well-known, but many of the minerals currently being evaluated for mining have no proven economically competitive methodology for extraction. The elemental distribution, grain size, and mineral type (such as phosphate, silicate, oxide, and carbonate) of each rare earth mineral must be assessed. 3. Processing Much of the cost in getting rare earths to the market is in the processing. Beneficiation, cracking, solvent extraction, and pilot plant operations are critical for understanding potential problems and solutions in processing, as well as streamlining each step. 4. Radioactivity Handling radioactivity in the mining and production of rare earths is critical, and issues such as worker exposure, transportation, and proper disposal of radioactive waste can be very expensive, and must be handled with community relations at the forefront of planning. 5. Marketing When marketing a rare earth project it is crucial to use realistic modeling. When modeling prices realized for rare earth products sold, historic pricing – both high and low – as far back as 10 years should be used. Also, it is important to make sure that the project will be making product that matches current market standards for the prices given. Pilot plant data, including recovery rates, should be included. Historical reagent costs should also be considered. 6. Rare Earth Product The final rare earth product must be an item of commerce that is desired by the market. This means that a given project must know that its products are either as good or better than current offerings in the market, or, if not, to know what discount should be applied. It must also be qualified by customers (a process that can take a year), and appropriate offtake agreements should be put in place. 7. Funding All projects need various amounts of funding. It should be kept in mind that costs and the market are constantly changing, and almost all projects go over budget.

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Introduction of the TESCAN Company and Product Line

The aim of this report is to introduce the company TESCAN to a wider audience. The first part of the report will focus on the company's background, staff, history and its present state, and the second part will cover TESCAN's product line. At the end of the report, TESCAN's important customers and users of TESCAN devices are listed. TESCAN was established in 1991. Its headquarters and production facilities are located in the city of Brno in the Czech Republic. The company's core business activities include research, development, manufacturing and worldwide supply of scanning electron microscopes and related products. Scanning electron microscopes, high resolution Schottky FE-SEMs, focused ion beam SEMs, signal detecting devices, SEM accessories and more, all belong to TESCAN's product range. The Czech Republic has a rich scientific tradition and the city of Brno has a long tradition in electron microscopy. As the second largest city in the Czech Republic, it is an industrial and commercial centre of Central Europe and several large trade fairs are held there annually. It is also a centre of culture and education. There are 6 universities with 27 departments and 120,000 students, and also containing 15 institutes of the Czech Academy of Science. Electron microscopy has a 70 years tradition in Brno. The first TEM was assembled at the Technical University of Brno in the 1940's. Tesla Brno introduced its first commercial TEM in 1953. In 1956 the Institute of Scientific Instruments of the Academy of Science of the Czech Republic was founded and Tesla BS-242 TEM was awarded a gold medal at World Exhibition held in Brussels in 1958. TESCAN was founded in 1991 by former engineers and managers of Tesla Brno and its SEM division. The company introduced its first fully PC-controlled SEM PROXIMA in 1996. In 1999 the VEGA SEM was introduced and won gold medal on 43rd International Engineering Fair in 2001. In 2003 TESCAN patented its Low Vacuum Secondary Electron Detector and in 2007 introduced the world's first live stereoscopic SEM imaging technology. From 2009 to 2011, TESCAN took part in a joint project within the Seventh Framework Programme of the European Union: FIBLYS – a Multifunctional Analytically Focused Ion Beam Tool for Nanotechnology. In 2010 and 2012 Jaroslav Klima - the general manager of TESCAN was named Entrepreneur of the Year in the South Moravian Region and he was also named 'Technology Entrepreneur of the Year 2011' in the Czech Republic. Nowadays, TESCAN has modern manufacturing facilities and modern clean laboratories; its premises have an area of 4500 m2 in total. The staff working at TESCAN are highly qualified and well-educated – 56% received university education, 9% are PhD degree holders. The company is divided into 5 divisions: Brno Division, Sales Division, Finance Division, TESCAN USA, Inc. and TESCAN CHINA, Ltd. Its worldwide network of distributors and subsidiaries deliver SEMs all around the world. The most important products are VEGA3 SEM, MIRA3 FEG-SEM, VELA3 FIB-SEM, LYRA3 FIB-FESEM, InduSEM, FERA3 plasma FIB FESEM, EasyProbe and TIMA. All SEMs are equipped with up-to-date technologies, such as Wide Field OpticsTM design, In-Flight Beam TracingTM, Beam Deceleration Technology or In-Beam Detectors.

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TIMA – TESCAN Integrated Mineral Analyzer: New approach for rapid evaluation of critical elements ore samples

Elemental distribution maps in 1 minute!

(HFSE-REE mineralsin carbonatites of Dashigou deposit, China)

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TIMA – TESCAN Integrated Mineral Analyzer: New approach for rapid evaluation of

critical elements ore samples