Pressure-temperature Estimates of the Basic Granulites and Conditions of Metamorphism in Sargur Terrain, Southern Karnataka and Adjoining Areas

Abstract

Chemistry of co-existing mineral pairs of opx-cpx ; opx-gt and cpx-gt from several metabasic rocks consisting of two pyroxene assemblages and recrystallised ultramafics from Hullahalli and Dodkanya of Sargur terrain and Sathyamangalam, along with data taken from recent literature are utilized to estimate the Pressure-Temperature conditions of metamorphism. Temperature estimates are around 767±50°C and average pressures of 8-9 kbs indicate the peak of metamorphism which operated in the Sargur terrain. This suggests a crustal thickness of 30-35 krn, which was attained prior to the onset of granulite facies metamorphism.