The South Tibetan Detachment System, Himalayan Orogen: Extension Contemporaneous With and Parallel to Shortening in a Collisional Mountain Belt

Six transects mapped across the boundary between the Tibetan sedimentary sequence and the underlying Greater Himalayan metamorphic sequence in southern Tibet demonstrate that a series of gently north-dipping normal faults, the South Tibetan detachment system, separates these two rocks sequences. Down-to-the-north movement on the detachments was Miocene to perhaps Pliocene in age and contemporaneous with structurally lower south-vergent thrusting within the Himalayan orogen to the south; thus, shortening and extension were contemporaneous and parallel at two different levels within the Himalayan and south Tibetan crust. Mapping during this study indicates that the South Tibetan detachment system continues for at least...