Rd. Raju et al., SULFUR ISOTOPIC STUDY ON THE VEIN-TYPE BARYTE FROM VEMULA IN THE VEMPALLE FORMATION OF CUDDAPAH BASIN, ANDHRA-PRADESH, Journal of the Geological Society of India, 49(6), 1997, pp. 693-697
Baryte at Vemula near to the southwestern margin of Cudapah Basin occu
rs as a vein-type deposit discordant to both the carbonate rocks of Ve
mpalle formation and its intrusive dolerite. S-isotopic data on the ba
ryte have a range of delta(34)S(CDT), between +16.2 parts per thousand
and +23.3 parts per thousand whereas the coexisting chalcopyrite has
a restricted range between +10.9 parts per thousand and +11.4 parts pe
r thousand. The average value of delta(34)S of Vemula baryte (+20.8 pa
rts per thousand) differs much from that of magmatic rocks (0 parts pe
r thousand to +2.5 parts per thousand), metamorphic rocks (+3 parts pe
r thousand) and sediments of continental margins, platform areas and g
eosynclines (-12.5 parts per thousand -17.1 parts per thousand), but i
s similar to that of sea water (+20 parts per thousand) which appears
to be the source for sulphur. The narrow range of delta(34)S of baryte
and chalcopyrite points to a uniform source with their sulphur possib
ly derived from sea water sulphate by bacteriogenic reduction.