Fluid Inclusion Studies and Sulphur and Strontium Isotope Geochemistry of Vein Barites of Velugumetla, Khammam District, Andhra Pradesh

The Velugumetla barite deposit, Khammarn district is studied for fluid inclusions, sulphur and strontium isotopes The inclustons that are random in distnbution and varying in size from 15-30 μ are classed as primary and the inclusions le ss than 15 μ in size and having linear trails as secondary Heating runs of the primary and secondary inclusions show peaks at 235° C to 245 °C(T_h) and 130°C to 140°C respectively Both the primary and secondary biphase liquid rich(L+V) inclusions hornogenized by the disappearance of the vapour phase The composition of fluid has been surmised as H₂O+NaCl+KCl The salinity was calculated as 12 7 wt% NaCI eqv The minimun depth of precipitation of barite was estimated to be 300 m and the density calculated as 0 94g/cm³ with a fluid pressure of 31 2 bars The fluid inclusion data of barite veins of vein bantes of Velugumetla, Khammarn district and other vein deposits of the Cuddapah Basin are correlatabte in terms of composition, salinity, density, pressure depth of entrapment and temperature of homogenization.

The δ³⁴S values for barite varies between +23 5 to+25 6 %O and pyrite has values between -0 9 to + 1 9 %O in case of the barite pyrite pairs that were studied from six different localities of the Cuddapah Basin and Khammam The δ<sup34 S values of the vein barite deposits of the Cuddapah Basin and Khammam area similar to the contemporaneous sea water The strontium isotope (⁸⁷Sr/⁸⁶Sr)ratios) show wide variation 0 705 to 0 722 for the vein barites of Cuddapah Basin and Kharnmam and indicates significant contribution of radiogenic Sr from older continental crust.