Slicing the High Himalaya of Western Nepal and Tibet – Furthering our Understanding of Continental Collision and Extrusion (?)

Speaker: Mike Taylor
This talk will focus on the Himalayan-Tibetan orogen. The central Nepal-Himal is the archetypical example of a continent-continent collision and is well-explained by north-south shortening accommodated along the Main Frontal thrust that soles into the Main Himalayan thrust fault. However, the area of central Nepal only accounts for a small fraction of the Himalayan collision zone. To the west, convergence obliquity increases between the Indian subcontinent and Eurasia. Commensurate with this increase in convergence obliquity is an increase in the arc-parallel component of displacement accommodated along the newly discovered dextral Western Nepal fault system. This dextral fault system can be traced for approximately 300 km along-strike based on field observations and remote sensing, and connects the Himalayan thrust front with the Gurla Mandhata massif and dextral Karakoram fault in southwest Tibet. This structural relationship implies segmentation of the Himalayan thrust wedge forming a continental version of a “forearc sliver”. Furthermore, slip transfer from the Karakoram fault into and along the dextral Western Nepal fault system negates with the classic view that dextral faulting along the Karakoram fault and Indus-Yarlung suture zone facilitates the eastward extrusion of Tibetan crust.