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Authors
Affiliations
1 Department of Geology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata - 700 019, IN
2 Natural Resources Canada, Geol. Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, CA
3 Nepal Metal Company Limited, Gyantole, Gyaneshwor, Post Box 468, Kathmandu, NP
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 65, No 6 (2005), Pagination: 725-737
Abstract
The Ganesh Himal Zn-Pb deposit in central Nepal has been highly deformed and metamorphosed together with its host rocks. Pb isotope data for the deposit are interpreted to define an age of about 875 to 785 Ma, which is permissive of age equivalence to the upper Vindhyan Supergroup of the North-Central and northwestern Indian Shield. The slightly positive to slightly negative sulphur isotope values for the Ganesh Himal deposit are in accord with coeval seawater sulphate δ
34S values in the range +15 to +20 %, and thus with an age greater than about 650 Ma. Apparent equilibrium sulphur isotope fractionation temperatures for sulphide pairs are generally 500°C to 750°C, a range that agrees with Kyanite-Staurolite and Biotite-Staurolite assemblages.
The 875 to 785 Ma age for Ganesh Himal has been calculated on the basis of Pb isotope ratios and age data for other Neoproterozoic and Cambrian Sediment-Hosted deposits. These Ganesh Himal results and those for the Genekha deposit, Bhutan, help confirm the previously postulated widespread distribution of Vindhyan rocks in Himalayan metasedimentary belts. The available Pb isotope and age data for the Amjhor deposit, in Upper Vindhyan rocks in Bihar State, India, are suggestive but not confirmatory of a tentative condusion that the Ganesh Himal deposit is its age equivalent.
Keywords
Pb and S Isotopes, Zn-Pb Deposit, Genesis, Ganesh Himal Deposit, Central Nepal Himalaya.
