Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

K. K. Pandey ¹, K. S. Mishra ¹, U. K. Pandey ², P. V. Ramesh Babu ²

Affiliations
1 Atomic Minerals Directorate for Exploration & Research, CR, Nagpur - 440001, IN
2 Atomic Minerals Directorate for Exploration & Research, Hyderabad - 500016, IN

Abstract

Whole-Rock isochron dating of granite gneiss, hosting rare element-Bearing pegmatites from Jharsuguda district, Orissa defines an isochron age of 2762±±200Ma with initial ⁸⁷Sr/⁸⁶Sr ratio of 0.7082 ± 0.0027 (MSWD = 36.8). High ⁸⁷Sr/⁸⁶Sr ratio indicates involvement of crustal source for its formation. Petrography of the granitoids characterizes them as 'hornblende granite gneiss'. The ASI of the granite gneiss reveals its meta-Aluminous nature. It is a significant host to the zoned and complex type of 'Rare Elements-Bearing Pegmatites' , containing columbite-Tantalite (oxide of Nb + Ta) and beryl. Based on the whole-Rock isochron data, the granite gneiss of the Jharsuguda area can be equated with the Bamra and Tamparkola granite and phase III of the Singhbhum granite. Further, it postdates the Bonai and Kaptipada granite but is older to the Nilgiri and Ramapahari granite, with all these forming part of the Singhbhum North Orissa Craton.

Keywords

Rb-Sr Geochronology, Granite Gneiss, Rare Metals, Jharsuguda, Orissa.

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K. S. Mishra ¹, P. Jagadeesan ¹, K. K. Pandey ¹, V. P. Saxena ², R. M. Sinha ²

Affiliations
1 AMD, CR, Nagpur - 440 001, IN
2 AMD, Hyderabad-500 016, IN

Abstract

Rare earth element (REE) geochemistry of uranium bearing columbite-tantalite and multiple Nb-Ta oxide phases from the Pandikimal-Jangapara pegmatites, Jharsuguda district, Orissa have been studied and evaluated columbite-tantalite from these areas contain low ∑REE (100-1000 ppm) with LREE/HREE_CN<0.5 and minor amounts of uranium (0.3-0.6 % U₃O₈). Multiple oxide phases (yttrotantalite, samarskite, microlite and fergusonite) contain elevated amounts of U (10-11 % U₃O₈) and REE (19-28 %) with HREE>LREE. Plot of ∑REE vs. Chondrite-Normalised LREE/HREE shows positive correlation in 'U' rich multiple oxides compared to those from columbite tantalites which tend to show a negative correlation. The LREE/HREE ratio is 0.24 with negative Eu anomaly (Eu/Eu = 0.1) indicating evolved nature of these pegmatites.

Keywords

Rare Earth Element (REE), Columbite-Tantalite, U-Bearmg Multiple Oxide Phases, Pandikimal, Orissa.

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