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

O. Van Breemen ¹, D. R. Bowes ², C. C. Bhattacharjee ³, P. K. Chowdhary ³

Affiliations
1 Geological Survey of Canada, Ottawa, Canada KIA OE8, CA
2 Department of Geology, University of Glasgow, Glasgow G12 8QQ, Scotland, GB
3 Department of Geological Sciences, Gauhati University, Guwahati 781014, Assam, IN

Abstract

A granite that cuts the basement gneiss complex yields a five point errorchron giving an age of 647 ± 122 Ma. Uniform Rb-Sr isotopic ratios on the scale of a small quarry (c. 20 m) permit calculation of a maximum age of 850 Ma. Muscovite books from a second of three sets of pegmatite veins to cut the granite yield an Rb-Sr age of 505 ± 5 Ma. Both whole-rock and mineral age data are interpreted as representing times of crystallization and are in the time range of Pan-African activity known from, other fragments of Gondwanaland.

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