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Bagchi, A. K.
- Proterozoic Iron Oxide (Cu-Ni-U-REE) Type Mineralisation in the Environs of Dalma Volcanics, West Singhbhum District, Bihar. A New Horizon for Exploration of Polymetallic Ores
Authors
1 Atomic Minerals Division, Jamshedpur-831 002, IN
2 Atomic Minerals Division, Hyderabad-500 016, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 54, No 5 (1999), Pagination: 491-494Abstract
Significant uranium geochemical anomalies associated with Cu, Ni, REE, Au indicative of favourable Iron oxide breccia type of mineralisation has been located along a sympathetic faulted zone close to the main fault along the northern contact of Dalma volcanic range. The assemblages of the rocks found north of Dalma volcanics viz., carbon phyllite, carbonaceous quartzite, calc-arenite and cherty quartzite are indicative of typical marine environment of lower to middle Proterozoic age traceable for about 10 km over a 3-7 km wide zone. The mineralisation represented by iron oxide breccia is confined to a major structural zone parallel to a regional strike fault and is cut across by transverse faults. Significant anomalous concentration of U3O8 (140-770 ppm), Cu (173-498 ppm), Ni (148-1566 ppm), Au (<0.25 to 1.6 ppm), Ag (1.2 to 4.29 ppm) and REE (Y 131 to 607 ppm, La <50 to 993 ppm, Ce 41 to 91 ppm) points to its economic potentiality. The geological characteristics and tectonic set-up are akin to the major iron oxide (Fe-Cu-Ni/U-REE-Au) type of deposits reported elsewhere in the world. Investigation on the economic potentiality of the mineralisation is under progress.Keywords
Economic Geology, Polymetallic Mineralisation, Dalma Metavolcanics, Iron Oxide Breccia, Singhbhum Craton, Bihar.- A Note on Petrography and Chemistry of Microgranular Enclaves and Granitoids around Talbahat, Lalitpur District, Uttar Pradesh
Authors
1 Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad - 500 016, IN
2 Atomic Minerals Directorate for Exploration and Research, Nongmynsong, PO Assam Rifles, Shillong-793 001, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 65, No 1 (2005), Pagination: 92-96Abstract
No Abstract.- Geochronology of the Granitoids of the Kunjar Area, Sundergarh District, Orissa: Implications to the Regional Stratigraphy
Authors
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy Bangalore - 560 072, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy NewDelhi - 110 066, IN
3 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy Hyderabad 500 016, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 65, No 4 (2005), Pagination: 428-440Abstract
Rb-Sr isotopic data for the Tamparkola granite, northwest of Bonaigarh, and Bamra granite, southeast of Barnra, Sundergarh district, Orissa have yielded similar ages of 2746𫏸 Ma and 2738±28 Ma, respectively. Small granite exposures intruding the Iron Ore Group in the southern part of Tamparkola granite, have also indicated similar Whole Rock Rb-Sr age of 2867䕺 Ma. These may be correlated with the Bonai granite. Significant crustal component was involved in the generation of these granites, as indicated by high initial Sr ratio, and their emplacement probably marks a major terminal cratonisation event in northwestern part of the Singhbhum-North Orissa Craton.
Ths study does not support the view that the Tamparkola Granite is equivalent to the Itrna/Ekma granites that are intrusive into the Gangpur Group. These age results call for a revision of the stratigraphy of the Bonai-Gangpur tract, in that the Darjing Group unconformably overlies both the Bonai granite and Tamparkola granite, with the Mesoproterozoic Kunjar sedimentary sequence representing the youngest of the regional succession.
Keywords
Rb-Sr isotopics, granites, stratigraphy, Kunjar basin, Darjing Group, Gangpur Group, Sundergarh District, Orissa.- Petromineragraphy and Mineral Chemistry of Bituminous Shale-Hosted Uranium Mineralisation at Sonrai, Lalitpur District, Uttar Pradesh
Authors
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.- Geochemistry of the Granites from Jharsuguda District, Orissa: Implications for Rare Metal Mineralisation
Authors
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Jamshedpur-831002, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 57, No 6 (2001), Pagination: 539-544Abstract
Jharsuguda Granite is intruded by several pegmatitic bodies, including rare metal bearing ones hosting columbite-tantalite and beryl. Geochemically, it is a silica-rich, metaluminous to peraluminous and potassic granite enriched in trace elements such as Rb, Nb, Zr, Y, Ga and Th, and depleted in Ba, Sr and Ti resulting in high Rb/Sr, Rb/Ba and Ga/Al ratios. The petromineraiogical and geochemical characters indicate Jharsuguda Granite as an A-type, within plate granite (WPG), emplaced around 650°-700°C at an assumed pressure of 5 kb. The granite has characteristics similar to niobium-yttrium-fluorine (NYF) bearing, A-type fertile granites.Keywords
Granitic pegmatites, Rare Metals, Jharsuguda, Orissa.- Note on the Uranium Mineralisation in the Quartzites of Kuladera Area, Sambalpur District, Orissa
Authors
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Bangalore - 560 072, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Hyderabad - 500 016, IN