The Karimnagar Granulite Terrane-A New Sapphirine Bearing Granulite Province, South India

A new terrane of granulite facies rocks-the Karimnagar granulite terrane (KGT) is identified. The KGT is ∼ 150 km x 20 km extending along NW-SE in the Karimnagar, Warangal and Khammam districts of Andhra Pradesh along the southern flank of the Godavari graben which separates the Dharwar and Bastar Cratons. The KGT is interesting because of its location far outside the known charnockitic region of south India. The important rock types in the KGT include : hypersthene granite (charnockite), two pyroxene granulite, calc-granulite and sapphirine bearing pelitic rocks. The association of sapphirine with orthopyroxene and cordierite in the pelitic rocks indicates metamorphism at pressures of ∼ 7 Kbar and temperatures of ∼ 750°C.

It is suggested that the KGT is a remnant of an Archaean supracrustal-granite association which underwent granulite grade metamorphism at ∼ 2.5 Ga ago. This ancient orogenic belt appears to have been exhumed during the early Proterozoic.