Abstract

This seminar will address the significance of crustal melting during prograde metamorphism, and its place within the complex causal chain of events that ensues during a continental collision: Does melting drive the tectonics, or do the tectonics cause melting? One way to answer this question is to focus on the location of Miocene granite outcrops found within the Himalayas, and attempt to determine their origin; this can be done using a wide range of evidence, including Nd isotopes in garnets, which allow very accurate dating of their decompression paths, and Hf-O isotopic data in zircons. Additionally, models describing dehydration & decompression melting in the crust, and the rheological consequences of crustal anatexis, can be constructed. Proceeding to ground such models in geochemical observations, one can attempt the further study of regional-scale dynamics during a continental collision in an integrated framework that considers both the brittle and ductile behaviours of rock, as well as the transitions between these two schemes. Finally, the roles of channel flow, the monsoon, and erosion across the Himalayas shall also be considered.