Preliminary Petrological Studies of Basement Rocks, Thar Coal Basin, Thar Parkar District, Sindh, Pakistan

The basement rocks encountered in exploratory boreholes drilled for exploration and evaluation of coal deposits in thar parkar district, sindh pakistan have formed the basis for present studies. the basement complex was penetrated through eighteen boreholes at drill depth range from 112 to 279 meters. these rocks were identified in field as pink and grey granites.. the basement rocks are of igneous as well as metamorphic origin. the igneous rocks identified petrographically are alkali-feldspar granite, granodiorite, rhyolite, rhyodacite and aplite while that of metamorphic origin is plagioclase hornblende gneiss. these rocks are termed as thar granitoids. the chemical data plotted in various binary and ternary diagrams suggests that the thar granitoids are (1) in general peraluminous in nature (2) restricted to psuedoternary minimum at moderate water pressure.