Petrology and geochemistry of amphibolites in and around Yenkur village, Khammam district, Andhra Pradesh, India

An area of about 140 sq.km around Yenkur village in Khammam district of Andhra Pradesh, India consisting of diverse metamorphic rocks ranging from amphibolites to granulite facies of metamorphism has been mapped on 2 cms to 1 km scale.

Petrographic work has been carried out for 60 sections of amphibolitic rocks. The anorthite content of plagioclase is An35-45 in hornblende schists and An39-48 in amphibolites. In amphibolites, almandine garnet is quite abundant.

Six rock samples of hornblende schists, 30 of amphibolites, have been chemically analyzed for major elements and 20 samples of amphibolites for trace elements have been analyzed. Petrochemical calculations including Niggli values and CIPW norms have been carried out. Two co-ordinate and three coordinate diagrams based on these calculations have been constructed to decipher the petrogenesis of amphibolites.