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Babu, E. V. S. S. K.
- Chemistry of Eclogitic Garnets from Bahradih Kimberlite, Raipur District, Madhya Pradesh
Abstract Views :180 |
PDF Views:2
Authors
Affiliations
1 National Mineral Development Corporation Limited, Khanij Bhawan, Masab Tank, Hyderabad - 500 028, IN
2 Atomic Minerals Division, Begumpet, Hyderabad - 500 016, IN
1 National Mineral Development Corporation Limited, Khanij Bhawan, Masab Tank, Hyderabad - 500 028, IN
2 Atomic Minerals Division, Begumpet, Hyderabad - 500 016, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 56, No 4 (2000), Pagination: 425-430Abstract
Garnet concentrates from the Bahradih kimberlite pipe were analysed by electron microprobe and found to be mostly of the pyrope-almandine variety with significant amount of Na2O and a pyrope content in the range of 48.76-61.45%, almandine 30.82-41.97% and grossular 2.313-9.983%, indicating eclogitic paragenesis. Their Mg# ranges from 53.92 to 66.59. The presence of traces of Na and Ti in these garnets indicates that substitution of these elements into the garnet structure is feasible at high pressure. Five out of 50 garnets analysed from Bahmdih show Na2O = 0.07 wt.% which indicates that they are from the diamond stability field, as confirmed further by the recovery of diamonds from the pipe.Keywords
Kimberlite, Garnet, Pyrope, Almandine, Diamond, Raipur District, Madhya Pradesh.
- Occurrence of Palladian Melonite in Jaduguda Uranium Deposit, Singhbhum Shear Zone, Bihar
Abstract Views :192 |
PDF Views:2
Authors
Affiliations
1 Ore Dressing Section, Bhabha Atomic Research Centre, Begumpet, Hyderabad - 500 016, IN
2 Department of Earth Sciences, University of Cambridge, GB
1 Ore Dressing Section, Bhabha Atomic Research Centre, Begumpet, Hyderabad - 500 016, IN
2 Department of Earth Sciences, University of Cambridge, GB
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 51, No 6 (1998), Pagination: 759-760Abstract
Palladian melonite, containing upto 7% palladium is reported for the first time from the uranium ores, Jaduguda Mines.Keywords
Mineralogy, Palladian Melonite, Uranium, Singhbhum, Bihar.- Fossil Pigeonites and Exsolution Features in Pyroxenes from Ferrosyenites of South India
Abstract Views :168 |
PDF Views:2
Authors
Affiliations
1 Department of Geology, Osmania University, Hyderabad 500007, IN
1 Department of Geology, Osmania University, Hyderabad 500007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 41, No 4 (1993), Pagination: 351-359Abstract
Pigeonites are typically absent in slowly cooled plutonic rocks, and ortho-pyroxene is totally unkown in alkaline rocks. Ferrosyenites and ferrornonzosyenites of the Chimakurti (Andhra Pradesh) and Sivamalai (Tamil Nadu) areas in south India contain both ortho- and clino-pyroxenes exhibiting various exsolution and inversion textures. The present study on these textures demonstrates the rare presence of 'inverted pigeonites' suggesting very high initial crystallization temperatures for the host rocks and also offers unambiguous evidence for the sub-alkaline (tholeiitic) nature of the host rocks.Keywords
Inverted Pigeonite, Ortho- and Clino-Pyroxenes, Ferrosyenites.- Petromineragraphy and Mineral Chemistry of Bituminous Shale-Hosted Uranium Mineralisation at Sonrai, Lalitpur District, Uttar Pradesh
Abstract Views :211 |
PDF Views:2
Authors
Affiliations
1 Atomic Minerals Directorate for Exploration and Research, New Delhi, IN
2 Atomic Minerals Directorate for Exploration and Research, Jamshedpur, IN
3 Atomic Minerals Directorate for Exploration and Research, Hyderabad, IN
1 Atomic Minerals Directorate for Exploration and Research, New Delhi, IN
2 Atomic Minerals Directorate for Exploration and Research, Jamshedpur, IN
3 Atomic Minerals Directorate for Exploration and Research, Hyderabad, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 63, No 3 (2004), Pagination: 291-298Abstract
Bituminous shale of the Sonrai Formation of the Bijawar Group hosts uranium mineralisation in Sonrai, Lalitpur dist., U.P. Mineragraphy of radioactive mineral phases viz. pitchblende and U-Si complex indicate that the pitchblende, apparently the first formed uranium phase, occurs as dispersed phase in the bitumen. Multistage remobilisation of uranium due to thermal gradient provided by basic and acid magmatic activity have resulted in the concentration of pitchblende along the fractures. EMP based mineral chemistry of pitchblende has shown negligible amount of Th02 and small amounts of RE203(0.78 to 0.90%) indicating its low-temperature formation. Chemistry of U-Si complex, a precursor phase of coffinite-like phase, suggests its formation from U-Zr-Y-REE-P-rich and Th-depleted hydrothermal fluid. High variability of PbO content in pitchblende and U-Si complex and resultant large range in their chemical ages suggest high degree of mobility and remobilization of Pb. Pyrite and chalcopyrite besides bitumen, are indicative of reducing environment necessary for the precipitation of pitchblende. Three major episodes of U-mineralisation based on the chemical ages of pitchblende (within bitumen: 413 Ma and as fracture fill: 51 Ma) and U-Si complex (1 to 13 Ma) have been inferred from this area.Keywords
Petromineragraphy, Mineral Chemistry, Pitchblende, Uranium Mineralisation, Sonrai, Uttar Pradesh.- REE Geochemistry of the Uranium Phases in Syn-Magmatic and Hydrothermal-Type U-Mineralisation: Two Case Histories from India
Abstract Views :188 |
PDF Views:2
Authors
Affiliations
1 Department of Atomic Energy, Begumpet, Hyderabad - 500 016, IN
2 National Geophysical Research Institute, Hyderabad - 500 007, IN
1 Department of Atomic Energy, Begumpet, Hyderabad - 500 016, IN
2 National Geophysical Research Institute, Hyderabad - 500 007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 62, No 1 (2003), Pagination: 23-35Abstract
Rare Earth Elements (REE) geochemistry of uranium-bearing phases from two genetically different types of uranium mineralisation is presented here. These include the syn-magmatic type, hosted by part of the Suryamalai or Sankari granite in the Kullampatti area, Tamil Nadu and hydrothermal vein type, hosted by both basement granitoid and its overlying Shahabad Limestone in the Bhima basin at Gogi, Karnataka. The study is based on the Electron Microprobe (EMP) analysis of selected REEs from different U-bearing phases, viz., uraninite, its pseudomorphic altered product of gummite, pitchblende and coffinite. Those hosted by granite, compared to that in limestone, have higher contents of XREE. Those in syn-magmatic type contain HREE>LREE and vice-versa in hydrothermal type. The former pattern is reflected in the co-existing Y- and HREE-bearing multiple oxides of fergusonite, samarskite and betafite. Furthermore, U-bearing organic matter and smectite-illite clay at Gogi contain higher contents of LREE. Pitchblende in both granite and limestone shows perceptible positive Ce-anomaly whereas the coffinite in limestone shows negative Ce-anomaly.In the plot of EREE vs. chondrite-normalised LREE/HREE, except for those in the granite-hosted syn-magmatic type, the rest of U-phases as well as uraninite from other types (taken from literature) define a trend of positive correlation. The minimum-end of the ZREE is represented by the unconformity-type of Collins Bay, Canada and Pine Creek deposits, Australia, and the maximum-end of SREE by hydrothermal vein type in the granite at Gogi. The syn-magmatic granite-hosted uraninite from Kullampatti, Rossing and Faraday plot close to each other, but away from the main positive trend toward a higher EREE.
In simple oxides of uranium, LREE, MREE and HREE, appear to co-exist or substitute, respectively, for Ca, Th and U, as indicated by the corresponding increasing trends. During post-magmatic alteration of uraninite to gummite and samarskite to betafite, there is a notable depletion of especially the HREE. During coffinitisation of pitchblende or replacement of coffinite by pitchblende, there is a similar depletion, especially the LREE in the former and the MREE in the latter.
- Petrography, Mineral Chemistry and Geothermobarometry of the Inukurti Anorthosite Complex and Associated Rocks from the Nellore Schist Belt, Andhra Pradesh
Abstract Views :193 |
PDF Views:2
Authors
Affiliations
1 Department of Geology, Osmania University, Hyderabad - 500 007, IN
2 Present address National Geophysical Research Institute, Uppal Road, Hyderabad - 500 007, IN
1 Department of Geology, Osmania University, Hyderabad - 500 007, IN
2 Present address National Geophysical Research Institute, Uppal Road, Hyderabad - 500 007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 62, No 4 (2003), Pagination: 413-428Abstract
The Inukurti Anorthosite Complex (IAC) forms a small elliptical dome (15 x 10 km) within the Archaean metamorphosed volcano-sedimentary sequences of the Nellore Schist Belt (NSB) The IAC comprises dominantly of anorthositic rocks, which are cut by mafic sills and dykes, volumetncally insignificant lenses and bands of dionte occur along its periphery All the rocks are deformed and metamorphosed under amphibohte-facies conditions but exhibit relict magmatic textures despite metamorphic recrystallisation and deformation The minerals from anorthosites diontes and amphibohtes exhibit compositional characteristics distinct to each groupGarnet-hornblende plagioclase-quartz equilibria from the IAC indicate a narrow range of metamorphic equilibration temperature between 644 and 570 °C, but a broad range of pressure between 76 and 27 kbar Geothermobarometry on zoned garnet porphyroblasts indicates that the rocks of the IAC were subjected to decompression of the order of about 5 kbar from 76 to 27 kbar related to rapid exhumation
Keywords
Anorthosite, Dionte Amphibohte, Geothermobarometry, Amphibohte facies, Inukurti Complex, Nellore schist belt, Andhra Pradesh.- Ree Geochemistry of the Uranium Phases in S YN-Magmatic and Hydrothermal-Type U-Mineralisation: Two Case Histories from India
Abstract Views :170 |
PDF Views:166
Authors
Affiliations
1 Flat B-203, Block-B, United Avenue Apts., South End, 7-1-29, Ameerpet, Hyderabad - 500 016, IN
2 3-27, Kavalipuram, (via) Velpur-Tanuku - 534 222, West Godavari District, Andhra Pradesh, IN
1 Flat B-203, Block-B, United Avenue Apts., South End, 7-1-29, Ameerpet, Hyderabad - 500 016, IN
2 3-27, Kavalipuram, (via) Velpur-Tanuku - 534 222, West Godavari District, Andhra Pradesh, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 62, No 4 (2003), Pagination: 516-516Abstract
No Abstract.Full Text
- X-Ray Powder Diffractometry and Electron Microprobe Study of Partially Disordered Wodginites from Challanpara Pegmatite, Bastar District, Chattisgarh
Abstract Views :205 |
PDF Views:2
Authors
Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Begumpet, Hyderabad - 500 016, IN
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Begumpet, Hyderabad - 500 016, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 59, No 3 (2002), Pagination: 201-212Abstract
The wodginite group of minerals occur in the Challanpara pegmatite, Bastar District, Chattisgarh. Nearly pure wodginite fractions were obtained by heavy liquid and electromagnetic separation. The mineral fractions havc been studied by X-ray powder diffractometiy and electron-microprobe analysis. Challanpara wodginite deviates from ideal formula MnSnTa208, or ABC2O8 by extensive substitutions at the B site. The Challanpara wodginites also host small hut significant amounts of Zr, W and traces of U. X-ray diffraction study indicates that these wodginites show partial cation disorder.. Upon heating the samples to ∼950°C, cell parameters such as interaxial angle P and cell volume showed notable changes suggesting partial ordering of the crystal structure. 'The calculated index of order (Δ) varies in a narrow range from 0.40 to 0.41 suggesting that the examined phases are "partially disordered wodginites".Keywords
Wodginite, Pegmatite, X-Ray diffraction, Electron microprobe, Challanpara, Bastar, Chattisgarh.- Uranium Mineralisation in the Neoproterozoic Bhima Basin at Gogi and near Ukinal: an Ore Petrological Study
Abstract Views :216 |
PDF Views:2
Authors
Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Hyderabad - 500 01 6, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Bangalore - 560 072, IN
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Hyderabad - 500 01 6, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Bangalore - 560 072, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 59, No 4 (2002), Pagination: 299-321Abstract
Uranium mineralisation in the Neoproterozoic Bhima basin todate has been found near Ukinal and at Gogi. U-mineralised phosphatic horizon near Ukinal includes the lithounits of phosphatic micritic limestonelchert and siliceous, calcareous phosphorite, some of which are manganiferous and glauconite-bearing. Uranium in these phosphatic rocks, correlatable with P2O5content (r>0.9), occurs mostly in collophanc and is difficult to extract. This mineralisation is sedimentary-diagenetic.Mineralisation at Gogi is more promising. This occurs within the major E-W trending Gogi-Kurlagere fault, near to its intersection with a NE-SW trending fault and is hosted by both brecciated, siliceous limestone and deformed basement rock represented by low-Ca biotite granite-granodiorite. Over 80% of the mineralisation at Gogi occurs as veins, veinlets and fracture-fills, composed of coffinite, lesser pitchblende, accessory U-Ti-Si complex (only in granitoid), associated intimately with reductants like sulphides and organic matter, and also clays (illite, smectite). Pitchblende is of two generations, both replaced by and replacing coffinite, and these two U-minerals, in turn, arc replaced by U-Ti-Si complex. The U-minerals occurring in limestone are Th-poor and are characterised by variable contents of U, Pb, Si and lanthanides (LREE>HREE), and as compared to those in granitoid are marked by higher contents of U, Pb, Fe and lower contents of Si and lanthanides. Amongst the sulphides, pyrite is predominant and occurs in three modes, viz., coarse euhedral-subhedral, framboidal and reticulate. The rest comprise marcasitc, chalcopyrite and galena in accessory to minor amount. These sulphides carry notable contents of Co, Ni, Se As, Ag and Au, with enrichment of Ag, Co, Ni in chalcopyrite followed by pyrite (more in framboidal type), Se in galena and Au more in sulphides from the granitoid. These high-value metals can be recovered as by-products during extraction of U. The organic n~atteris heterogenous and contains U, Si, Ca, Al, Pb and Fe, with the one rich in U is also high in the other elements. Radioactive clay contains U, P and REE. Both radioactive organic matter and clay are almost free of Th and Zr, with LREE>HREE. Paragenetically, the uranium minerals were formed later than the sulphides and organic matter. U-mineralisation at Gogi is poly-phase and poly-metallic, hydrothermal vein type with an Eh of -0.2 to -0.3V, pH of 7 to 8, and temperature of <200°C. The controls for this U-mineralisation are: (a) fertile granitoid as source, (b) structurally weak and permeable zones of faults, folds, brittle-ductile deformation and unconformity, along basin margin, (c) presence of strong reductants of organic matter and sulphides, (d) impervious and reactive cover rock of limestone and (e) dyke activity in the basement which may have acted as heat source and created necessary geothermal gradient for remobilisation and precipitation of U. These can be taken as guides for U-exploration in similar geologic set-up.
Keywords
U-Mineralisation, Hydrothermal, Neoproterozoic, Bhima Basin, Gogi, Ukinal, Karnataka.- Discrete Selenide Phases from the Uraniferous Mahadek Sandstones of Domiasiat and Wahkyn South, West Khasi Hills District, Meghalaya
Abstract Views :202 |
PDF Views:171
Authors
Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy 'Begumpet, Hyderabad - 500 016, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Shillong, Meghalaya, IN
3 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Tatanagar, Jamshedpur, IN
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy 'Begumpet, Hyderabad - 500 016, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Shillong, Meghalaya, IN
3 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Tatanagar, Jamshedpur, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 59, No 6 (2002), Pagination: 571-574Abstract
Occurrences of discrete selenide phases in the geological environment are rather rare and are confined to a few sulphide deposits and sandstone-type uranium deposits such as those of the Colorado plateau, USA. The occurrence of discrete selenide phases viz., clausthalite (PbSe), ferroselite (FeSe2) and Co-penroseite (CoNiCuSe2) are reported for the first time from the Uraniferous Mahadek sandstones of Domiasiat and Wahkyn South, West Khasi Hills District, Meghalaya. The selenide phases are associated with pyritiferous organic matter, pitchblende and other ore minerals such as marcasite and sphalerite.Full Text
- Chemistry of Eclogitic Garnets from Bahradih Kimberlite, Raipur District, Madhya Pradesh
Abstract Views :184 |
PDF Views:155
Authors
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 57, No 2 (2001), Pagination: 189-189Abstract
No Abstract.Full Text
- REE-HFSE Distribution/Partitioning Between Garnetiferous Restites and TTG from Nademavinapura Area, Western Dharwar Craton
Abstract Views :248 |
PDF Views:0
Authors
S. N. Charan
1,
E. V. S. S. K. Babu
1,
S. M. Naqvi
1,
J. G. Rana Prathap
1,
M. Ram Mohan
1,
D. Srinivasa Sarma
1
Affiliations
1 National Geophysical Research Institute (Council of Scientific and Industrial Research), Hyderabad - 500 606, IN
1 National Geophysical Research Institute (Council of Scientific and Industrial Research), Hyderabad - 500 606, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 73, No 3 (2009), Pagination: 371-378Abstract
The major part of the Peninsular Gneiss in Dharwar craton is made up of Trondjhemite-Tonalite-Granodiorite (TTG) emplaced at different periods ranging from 3.60 to 2.50 Ga. The sodic-silicic magma precursors of these rocks have geochemical features characteristic of partial melting of hydrated basalt. In these TTGs, enclaves of amphibolites (± garnet) are abundant. These restites are considered to be the residue of a basaltic crust after its partial melting. A detailed study of these (residue) enclaves reveals textures formed due to the process of partial melting. Major, trace and REE analysis of these residue enclaves and the melt TTGs and microprobe analysis of the coexisting minerals show partitioning of REE and HFSE between the precursor melt of TTGs and the upper amphibolite facies residues. Formation of garnetiferous amphibolites with biotite, Cpx and plagioclase consequent to melting, has squeezed the original MORB type of basaltic crust and given rise to the TTGs, depleted in Y, Yb, K2O, MgO, FeO, TiO2 and enriched in La, Th, U, Zr and Hf. Coevally during the process of melting, the hydrated basalt was depleted in Na2O, Al2O3, LREE, Th, U and enriched in K2O, MgO, Nb, Ti, Yb, Y, Sc, Ni, Cr and Co. Mineral chemistry of co-existing garnet-biotite and amphiboleplagioclase in these amphibolitic (restite) enclaves indicates an average temperature of 700 ± 50 °C and pressure of 5 ± 1 Kbar. These data are inferred to indicate that during the garnet stability field metamorphism, effective fractionation of HREE and HFSE has taken place between the restites having Fe-Mg silicates, ilmenites and the extracted melt generated from the MORB type of hydrated basalt. These results are strongly substantiated by the reported melting experiments on hydrated basalts.Keywords
Fractionation, HFSE, REE, TTG, Restite, Dharwar Craton.References
- BHASKAR RAO, Y.J., GRIFFIN, W.L., KETCHUM, J., PEARSON, N.J., BEYER, E. and REILLY, S.Y. (2008) An outline of juvenile crust formation and recycling history in the Archaean Western Dharwar Craton from Zircon in-situ U-Pb dating and Hf isotopic composition. (Abstract, Goldschmidt Conference, 2008).
- DRUMMOND, M.S., DEFANT, M.J. and KEPEZHINSKAS, P.K. (1996) Petrogenesis of slab-derived trondhjemite-tonalite-dacite/ adakite magmas. Trans. Royal Soc. Edinburgh, Earth Sci., v.87, pp.205-215.
- JAYANANDA, M. and PEUCAT, J.-J. (1996) Geochronological framework of Southern India. In: M. Santosh and M. Yoshida (Eds.), The Archaean and Proterozoic terrains of Southern India within East Gondwana. Gondwana Res. Group Mem., No.3, pp.53-73.
- KEMP, A.I.S. and HAWKESWORTH, C.J. (2003) Granitic perspectives on the generation and secular evolution of the continental crust. In: R.L. Rudnick (Ed.), The Crust: Treatise on Geochemistry. Elsevier-Pergamon, Oxford, v.3, pp.349-410.
- KERRICH, R. and POLAT, A. (2006) Archaean greenstone-tonalite duality: Thermochemical mantle convection models or plate tectonics in the early Earth global dynamics? Tectonophysics, v.415, pp.141-165.
- NAQVI, S.M., SRINIVASA SARMA, D., SAWKAR, R.H., RAM MOHAN, M. and RANA PRATHAP, J.G. (2008) Role of adakitic magmatism and subduction in gold endowment of Dharwar Neoarhaean greenstone belts, India. Jour. Geol. Soc. India, v.71(6), pp.875-888.
- PEUCAT, J-J., MAHABALESWAR, B. and JAYANANDA, M. (1993) Age of younger tonalitic magmatism and granulite metamorphism in the amphibolite-granulite transition zone of Krishnagiri area and comparison with the older gneiss from Gorur-Hassan area. Jour. Met. Geol., v.11 pp.879-888.
- RADHAKRISHNA, T., KRISHNENDU, N.R. and BALASUBRAMANIAN, G. (2007) Mafic dyke magmatism around the Cuddapah Basin: Age constraints, petrological characteristics and geochemical inference for a possible magma chamber on the southwestern margin of the Basin, Jour. Geol.Soc. India, v.70, pp.194-206.
- RAPP, R.P., SHIMIZU, N., NORMAN, M.D. and APPLEGATE, G.S. (1999) Reaction between slab-derived melts and peridotite in the mantle wedge: experimental constraints at 3.8 GPa. Chem. Geol., v.160, pp.335-356.
- RUDNICK, R.L. and GAO, S. (2003) The composition of the continental crust. In: R.L. Rudnick (Ed.),The Crust: Treatise on Geochemistry. Elsevier-Pergamon, Oxford, v.3, pp.1-64.
- SAMSONOV, A.V., BOGINA, M.M., BIBIKOVA, E.V., PETROVA, A.YU. and SHCHIPANSKY, A.A. (2005) The relationship between adakitic, calc-alkaline volcanic rocks and TTGs: implications for the tectonic setting of the Karelian greenstone belts, Baltic Shield. Lithos, v.79, pp.83-106.
- SUN, S.-S. and MCDONOUGH, W.F. (1989) Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In: A.D. Saunders and M.J. Norry (Eds.), Magmatism in the ocean basins. Geol. Soc. London Spec. Publ., no.42, pp.313-345.
- TAYLOR, S.R. and MCLENNAN, S.M. (1985) The continental crust: Its composition. Blackwell Scientific Publishers, Oxford, 312p.
- XIONG, X.L., XIA, B., XU, J.F., NIU, H.C. and XIAO, W.S. (2006) Na depletion in modern adakites via melt/rock reaction within the sub-arc mantle. Chem. Geol., v.229, pp.273-292.
- Compositional Study of Spinels from Wajrakarur Pipe-10 (Anumpalle), Ananthapur District and its Significance in Diamond Prospectivity
Abstract Views :164 |
PDF Views:3
Authors
Affiliations
1 National Mineral Development Corporation Ltd., Khanij Bhawan, Masab Tank, Hyderabad - 500 028, IN
2 Department of Earth Sciences. University of Cambridge, Cambridge CB2 3EQ, GB
3 Applied Geochemistry Department, Osmania University, Hyderabad - 500 007, IN
1 National Mineral Development Corporation Ltd., Khanij Bhawan, Masab Tank, Hyderabad - 500 028, IN
2 Department of Earth Sciences. University of Cambridge, Cambridge CB2 3EQ, GB
3 Applied Geochemistry Department, Osmania University, Hyderabad - 500 007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 52, No 6 (1998), Pagination: 677-682Abstract
Geological Survey of India had recently discovered Wajrakarur pipe-10 and spinels from this pipe were analysed. Q-cluster analysis of these spinels based on Cr2O3, Al2O3, TiO2 and MgO contents indicate the presence of S1, S3, S4, S5 and S10 groups. S1 group spinels are supposed to be cogenetic with diamond i.e., stable in the mantle within the P-T regime under which diamonds are known experimentally to form. The Cr/(Cr+Al) vs Fe/(Fe+Mg) plot also show that a few spinels are from the field of diamond inclusion chromites. This study suggests probable diamondiferous nature of the Anumpalle pipe.Keywords
Geochemistry, Mineral Chemistry, Kimberlites, Diamond, Spinel, Andhra Pradesh.- Cluster Analysis and Nickel Thermometry of Garnet Xenocrysts from Majhgawan Diamondiferous Pipe, Panna District, Madhya Pradesh
Abstract Views :187 |
PDF Views:2
Authors
Affiliations
1 Natl. Min. Dev. Corp. Ltd., Khanij Bhawan, Masab Tank, Hyderabad - 500 028, IN
2 Applied Geochemistry Department, Osmania University, Hyderabad-500 007, IN
3 Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, GB
1 Natl. Min. Dev. Corp. Ltd., Khanij Bhawan, Masab Tank, Hyderabad - 500 028, IN
2 Applied Geochemistry Department, Osmania University, Hyderabad-500 007, IN
3 Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, GB
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 52, No 3 (1998), Pagination: 273-278Abstract
Based on the Q-Cluster analysis of 536 garnet grains, the garnets of Majhgawan are classified as Group 1, Group 2, Group 9, Group 10 and Group 11. Group 10 garnets have very high MgO (21.2%) and moderate to high Cr2O3 (9.5%), combined with low CaO. MgO shows negative correlation with CaO and FeO and this cluster contains a large number of garnet inclusions in diamonds. The major element chemistry of these garnets confirm that they are moderately subcalcic and have high Crcontent with a well-defined Ca-Cr trend. Around twenty percent of garnets show harzburgitic trend indicating low to moderate grade of the pipe. Nickel thermometry has indicated a well-defined geotherm between 1150° - 1400°C and corresponds approximately to a slightly elevated 42 m W/m2 conductive model. Garnets with temperature > 1150°C probably were derived from diamond stability field. Based on Ni-thennometry (using only lower cut-off) omega value is calculated (<30) which suggests an average grade upto 15 ctpht for Majhgawan pipe.Keywords
Cluster Analysis, Geothermometry, Garnet, Diamond, Madhya Pradesh.- Nature of Suspended Particles in Hydrothermal Plume at 3°40'N Carlsberg Ridge:A Comparison with Deep Oceanic Suspended Matter
Abstract Views :184 |
PDF Views:110
Authors
Affiliations
1 CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004, IN
2 CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, IN
3 ESSO-National Centre for Antarctic and Ocean Research, Vasco da Gama, Goa 403 804, IN
1 CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004, IN
2 CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, IN
3 ESSO-National Centre for Antarctic and Ocean Research, Vasco da Gama, Goa 403 804, IN
Source
Current Science, Vol 112, No 01 (2017), Pagination: 139-146Abstract
Suspended matter from hydrothermal plume at 3°40'N Carlsberg Ridge was studied for microtexture and geochemistry. Characteristics of these plume particles were compared with deep-oceanic particulates from different depths. Compared to fine, deep-oceanic suspended matter (≤2.0 μm), some particles in the plume were larger (≥20 μm) and had irregular shape and surface. These plume particles were mostly composed of Fe-oxides and silicates. Bulk composition showed that plume particles were relatively enriched with Fe, P, Mn, rare earth elements (except Ce) and U, but had other trace element concentration analogous to that found in deep-oceanic suspended matter. Efficient scavenging of elements from hydrothermal fluid and sea water makes geochemistry of plume particulates different from common oceanic particles.Keywords
Deep-Oceanic Particulates, Geochemistry, Hydrothermal Plume, Micro-Texture, Suspended Particulate Matter.Full Text
- Precambrian Geodynamics
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Authors
Affiliations
1 CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, IN
2 Indian Institute of Science Education and Research, Kolkata, Mohanpur, Nadia 741 246, IN
1 CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, IN
2 Indian Institute of Science Education and Research, Kolkata, Mohanpur, Nadia 741 246, IN
Source
Current Science, Vol 118, No 1 (2020), Pagination: 15-17Abstract
Understanding the geodynamic processes that underpin the formation of continents is fundamental to decoding the complex evolutionary history of the Earth and the terrestrial planets. In the Phanerozoic Eon, the paradigm of plate tectonics and Wilson-cycle processes not only constitutes a robust and unifying mechanism to explain the orogenic processes of crust formation, recycling and preservation, but also the complex interactions among the solid earth, biosphere, hydrosphere and atmosphere relevant to evolution of life and climate. However, there is yet no consensus on a global geodynamic framework for the Hadean and Archean Eons.Full Text