FLUID INCLUSION CHARACTERIZATION OF AURIFEROUS QUARTZ VEINS OF BANSPAL BLOCK, KEONJHAR DISTRICT, ODISHA, EASTERN INDIA

Abstract

Fluid inclusions are small volume of paleofliiid that were trapped within crystals during initial growth from oIution or during localized crystallization along fractures at some later time. The minerals suitable for study of fluid inclusions are quartz, calcite, fluorite, topaz etc. Among them quartz offers the best chance of success because of its widespread geological occurrence, transparency and tendency to trap relatively large inclusions. Though fluid inclusions represent minuscule fraction of the fluid that was present, yet careful study of them can yield valuable information about that fluid. Fluid inclusion studies give an idea about fluid composition, ptocesSeS, ptessure, temperature and ore forming conditions of lode gold deposits. Studies of fluid inclusions from the vein deposits of Banspal block provided valuable information on the physico—chemical conditions of the ore fluid during mineralization.The area around Banspal block occupied by basaltic volcanic rock of Dhanjori Group (Malangtoli lava). In this area occurrence of gold found in the quartz vein. Gold is mainly associated within the crystal lattice of sulphide minerals like Pyrite, Arsenopyrite, Chalcopyrite From petrographic study it is observed that both primary and secondary biphase inclusions rich in liquid are present. 22 primary inclusions has been selected for thermometric analysis. Mainly four types of primary inclusions were identified such as I-120-rich, CO2. rich, CO2-1-120 and 1-120- salt inclusions. 1-120- Rich inclusions are homogenised between + 160.5 to +2400 C. CO2-Il2O mixed inclusions hornogenised mainly into liquid phase and temperature varies from +240 to > 2950 C. The mineralizing fluids have relatively low salinity (4-10wt% NaCL eq.), consistent density of CO2 (0.5- 0.8 0/cm3)