Convergent orogens worldwide share some common characteristics in their evolution: all result in crustal shortening, leading to thickened crust and isostatically-driven surface uplift. As higher elevations are reached (4–5 km), mountain ranges often undergo crustal extension, even as crustal shortening continues on the flanks of the mountain range (e.g., Dewey, 1988; Molnar and Lyon-Caen, 1988). The transition from shortening to extension is important to understand because it is a record of how forces are evolving within and outside the orogen.

This study investigates a region in the western Himalaya that provides a rare opportunity to investigate this transition from shortening to extension, as well as the magnitude of these processes, the depths at which they operate and their duration. In this talk Dr.Murphy will first review existing tectonic models and then describe several lines of evidence that point to an event in the late Miocene during which there was a dramatic inversion of the topography in southwestern Tibet. This inversion was most likely driven by outward radial expansion and coeval arc-parallel extension of the orogen. These observations were used to derive an internally consistent kinematic model for the Himalayan orogen since the Early Miocene. Dr. Murphy will share his experiences while conducting the field research and discuss the efforts required to obtain funding.

Zada basin in western Tibet near the China-India border (Latitude 31 degrees North, Longitude 79 degrees East).

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