Tectonics of the Central crystallines of Western Himalaya

Abstract

The crystalline sheet of the Higher Himalaya, referred to as the Central Crystallines, is a continuous lithotectonic unit which can be traced from the River Kali of eastern Kumaun in the east to Sankoo in the Suru River valley of Kashmir in the west. The principal lithostratigraphic units of this zone are pelites, psammites, gneisses, amphibolites, migmatites and leucocratic granites. The rocks of this zone show progressive regional metamorphism of normal as well as reverse types, the metamorphic grade ranging from chlorite to sillimanite zone. The Main Central Thrust, which demarcates the southern boundary of the Central Crystallines, has brought the crystalline rocks to rest over the sediments of Deoban Group in Kumaun and Garhwal and over the Outer Crystallines (=Chail-Jutogh Nappe) in Himachal Pradesh. The evidence obtained from metamorphism, deformation and radiometric dating indicate that the Central Crystallines is an old Precambrian basement which has been reactivated during Caledonian and Alpine orogenic movements.