The structure and stratigraphy of SE Zanskar, Ladakh Himalaya

A field study of over 4 km thickness of Cambro-Ordovician to Cretaceous sediments deposited on the passive margin of northern India has provided significant new data on the thickness, age and depositional environments of these deposits. The first detailed structural map of the Phuctal area and a regional map of Eastern Zanskar are presented, together with sequentially restored structural cross sections. An imbricate thrust duplex and a lateral ramp stack, which formed in the Phuctal area during SW-directed thrust propagation, were later deformed by NE-directed structures probably produced during gravitational collapse of the thrust stack. Collapse occurred along the previously documented Zanskar shear zone, and also by reactivation of the basal detachment of the Zangla nappe. This dorsal collapse of the orogen was probably related to an increase in uplift rate during the Neogene, and may have coincided with the initiation of the Main Boundary Thrust farther south.