Thermal Evolution of the Zanskar Shear Zone

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9418322 Harrison This project is to conduct 40Ar/39Ar analyses of a suite of samples already collected from the Zanskar shear zone in the Lhasa district of the central Himalayas in order to date the movement on this fault. The Zanskar shear zone is part of a major low-angle normal fault system known as the Southern Tibetan Detachment System that appears to span the entire length of the orogenic collision front. The timing of this remarkable feature is poorly constrained in the Zanskar region, although about 1000 km farther east the fault is known to have moved at 23-20 Ma. The project will measure 40Ar/39Ar on 16 separated minerals and determine detailed thermal histories, timing of fault initiation and slip-rate history. The results will provide needed insight on the origin and evolution of this extensional fault system and will help understand the tectonic evolution of other major compressional orogenic systems.