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

G. S. Sharma ¹, R. K. Purohit ¹, Minati Roy ¹, B. Sengupta ¹, Jagmer Singh ²

Affiliations
1 Atomic Minerals Division, Department of Atomic Energy, New Delhi-110066, IN
2 Atomic Minerals Division, Department of Atomic Energy, Hyderabad-500016, IN

Abstract

Radioactive alkali feldspar granite (alaskite) occurs as dykes within the Proterozoic granite gneiss around Dhanota. Samples have assayed 0.011 to 0.16% U₃O₈ and 0.005 to 0.16% ThO₂. Yttrium values range from 250 to 800 ppm. Uranothorite occurs in association with zircon, xenotime, magnetite, hematite, sphene and goethite. The U-Th-Y mineralisation in alaskites of Dhanota is disseminated syn-magmatic intrusive type.

Keywords

Economic Geology, Geochemistry, Petrography, Alaskite Dyke, Xenotime, Uranothorite, Dhanota, Haryana.

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A. N. Basu ¹, G. S. Sharma ¹, H. M. Varma ¹, R. Dhana Raju ¹, N. K. Dougall ¹, N. V. Raju ¹

Affiliations
1 Atomic Minerals Division, Department of Atomic Energy, Hyderabad 500016, IN

Abstract

At Maturigiri and Dhurkantagiri, mineralised coarse-grained quartz syenite bodies (up to 10 x 2 m) occur as intrusives along the NNW-SSE trending joints in the gneissic country rock. Mineralogically. the quartz syenite is characterised by over 50% K-feld-spar, lesser plagioclase, quartz, mica, garnet and chlorite, together with accessory uraninite, monazite, molybdenite and pyrite. Uraninite occurs as euhedral to subhedral inclusions and mineralisation is syngenetic. Two types of monazite, Th-poor and Th-rich, are present. Molybdenite occurs as veins along fractures and appears to be of late hydrothermal origin. The mineralogical and textural features suggest that quartz syenite was formed from a residual melt of granitic magma of crustal origin.

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D. Bhattacharya ¹, G. B. Joshi ¹, G. S. Sharma ², D. B. Sen ³

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, New Delhi-110066, IN
2 Atomic Minerals Directorate for Exploration and Research, Jaipur -302030, IN
3 Atomic Minerals Directorate for Exploration and Research, 313/4, Sector-56, Rail Vihar, Gurgaon, Haryana, IN

Abstract

Surface indications of uranium mineralisation associated with ferruginised brecciated rocks is traceable, intermittently, over a strike length of 25 km, exposed along the Jamual -Markundi Fault (JMF), at the tectonic contact of Neo- to Meso-Proterozoic Vindhyan Supergroup and Paleo-Proterozoic Mahakoshal Group between Gurdah and Mohariya, Sonbhadra and Sidhi districts of U.P. and M.P. respectively. Preliminary investigations reveal uranium (U₃O_g) content upto 610 ppm with little or no ThO₂. Uranium occurs in adsorbed state in the ferruginised groundmass of brecciated rock and probably related to hydrothermal activity. This is the first reported uranium occurrence from this unconformity related geological set up in the Son valley.

Keywords

Uranium mineralisation, Unconformity, Jamual-Markundi fault, Son-valley, U.P., M.P.

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