Initiation of the Himalayan Orogen as an Early Paleozoic Thin-skinned Thrust Belt

Research by many workers in various regions of the Himalaya, combined with our recent geologic and geochronologic studies in Nepal, indicate that fundamental aspects of the Himalayan orogen originated in an early Paleozoic thrust belt and are unrelated to Tertiary India-Asia collision. Manifestations of early Paleozoic tectonism include ductile deformation, regional moderate-to highgrade metamorphism, large-scale southvergent thrusting, crustal thickening and the generation of granitic crustal melts, uplift and erosion of garnet-grade rocks, and accumulation of thick sequences of synorogenic strata. Determining the relative contributions of early Paleozoic versus Tertiary tectonism constitutes a significant challenge in understanding the Himalayan orogen.