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Authors
Affiliations
1 Institute of Geology of Ore Deposits (IGEM) Academy of Sciences, 35, Staromonetnii Street, Moscow, USSR, RU
2 Chitradurga Copper Co., IN
3 Mineralogical Inst., University of Mysore, Manasa Gangotri, Mysore 6, IN
4 Dept. of Geology, University of Delhi, Delhi 7, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 21, No 3 (1980), Pagination: 107-116
Abstract
The isotope composition of leads from ore deposits in general reflects the age of ore mineralisation and its genetical features. Two examples have been given to illustrate a direct connection of ore lead isotope composition with the source ore. Calculations of the model age from lead isotope data form the basis for genetic reconstructions of Precambrian deposits. Radical improvement in the accuracy of mass spectrometric isotope lead analysis has made possible the employment of two-stage and in some cases more complicated models for genetic reconstructions. The Penehanga Bay lead-zinc deposit and gold-silver deposits of South Dakota have been studied using high accuracy mass spectrometer. Both the deposits show that ore formation took place one to two billion years after craton formation, and lead present in ores originated at least from two different Sources.
Keeping this background of experience, fifteen galena samples from five sulphide and gold-sulphide deposits of the Indian Shield have been selected and determination of lead isotope composition has been carried out by the Soviet authors in the USSR using recently developed M.I.1320 Mass Spectrometer. The isotopic ratios of galena from Ingaldhal copper deposit are the most primitive among the analysed ores of the Indian Shield. The results of lead isotopic determination have been interpreted in terms of the general theory of 'plumbotectonics '.
