Mountain building in the Nepal Himalaya: Thermal and kinematic model from 20 My to present

We describe a model of crustal deformation and thermal structure across the Nepal Himalaya over the last 20Myr. The model assumes that, throughout this period, shortening across the range has been entirely taken up by slip along a single thrust fault, the Main Himalayan Thrust (MHT) Fault, and that the growth of the Himalayan wedge has resulted from the development of a duplex at mid-crustal scale. We show that this process explains the inverse thermal gradient documented throughout the Lesser Himalaya, the discontinuity of peak metamorphic temperatures across the MCT, as well as the age gradient of exhumation across the range. This study shows that the Himalayan range has primarily grown by underplating through the development of a mid-crustal duplex straddling the brittle-ductile transition on the MHT.