Time and place of progressive regional metamorphism: a study from the Precambrian of eastern India

Abstract

Structural and metamorphic studies around Ghatsila in the Precambrian terrain of eastern India show a remarkable accord between the structural surfaces and the metamorphic isograds, with the higher and lower grade rocks occurring respectively at deeper and shallower tectonic and stratigraphic levels. Higher grade minerals developing after lower grade ones prove that the regionally metamorphosed series is progressive in time, and the broad contemporaneity between the folding movement and the formation of index minerals points to a genetic relation between folding and metamorphism. The possible cause of regional metamorphism has been suggested.