The High Himalaya

Abstract

Age of the Main Central Thrust, at different places, obtained by different methods is described. Litho-tectonic subdivisions are mentioned along with magmatic events. Both Vaikrita and Munsiari rocks represent two distinct rock assemblages and both have undergone pre-Himalayan metamorphism. A model is proposed to explain the occurrence of younger Vaikrita rocks on the thrust hanging wall and older Munsiari rocks in footwall of the Vaikrita thrust. The model is based on reactivation of early rift related normal fault as thrust fault. Details of structural features along the Satluj valley are described primarily to explain the interference between Karcham oblique fault ramp and two generations of folds. Change in orientation of early and superposed folds in vicinity of Vaikrita thrust is illustrated. Field evidence suggests that after locking of the Vaikrita thrust, the maximum extension has taken place along the strike of the thrust. Different models proposed for structural evolution of the High Himalaya are reviewed.