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

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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