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K. S. Mishra ¹, K. R. Gupta ¹, A. K. Bagchi ¹, Singh Jagmer ²

Affiliations
1 Atomic Minerals Division, Jamshedpur-831 002, IN
2 Atomic Minerals Division, Hyderabad-500 016, IN

Abstract

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.

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A. V. Subrahmanyam ¹, K. K. Sinha ², A. K. Bagchi ¹

Affiliations
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

Abstract

No Abstract.

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A. Chaki ¹, D. Bhattacharya ², J. S. Rao ³, A. K. Chaturvedi ³, A. K. Bagchi ³

Affiliations
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

Abstract

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&#177144 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&#17786 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.

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Minati Roy ¹, A. K. Bagchi ², E. V. S. S. K. Babu ³, Brindaban Mishra ¹, P. Krishnamurthy ³

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

Abstract

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.

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Shailendra Kumar ¹, Anjan Chaki ¹, A. K. Bagchi ¹

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Jamshedpur-831002, IN

Abstract

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.

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A. Panneerselvam ¹, J. S. Rao ², A. Chaki ¹, A. K. Bagchi ²

Affiliations
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

Abstract

Uranium mineralisation has been discovered recently in quartzites near village Kuladera, 15 km ESE of Bamra, Sambalpur district, Orissa. The radioactive quartzites are occurring at the base of the metasedimentary sequence, which is unconformably resting over the unclassified granitoiddgneisses of late Archaean age. Two mineralized quartzite bands, separated by a basic body of epidioritelamphibolite, have been identified. The samples radiometrically assayed 0.018 to 0.15% U₃O₈ and are free of thorium. The uranium minerals identified are uraninite, gummite, torbernite and U-Ti complex. The other mineral phases contributing to the radioactivity are metamict allanite, zircon, anatase, limonite, epidote and goethite. The samples also analysed higher concentration of Ti, V, Cr, Zr, Cu, Mo, Pb and Ag. As the uranium mineralisation is at the unconformity between the Proterozoic metasediments and basement crystallines, it opens up a new and promising potential target area in this part of Orissa for uranium exploration.

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