Field, Analytical, and Experimental Studies of Progressive Crustal Melting in the Himalaya

点击翻译按钮获取中文摘要

9814497HodgesThe metamorphic core region of the Himalaya displays spectacular exposures of leucogranites produced by partial melting of the continental crust. These melts were produced over a wide range of pressure and temperature conditions as the orogen evolved through Late Oligocene to Middle Miocene time. This research will capitalize on the opportunity presented by the Himalaya to better understand the process of orogenic anatexis in time and space. Over a three-year period, an integrated field, petrologic, and geochemical study of multiple generations of leucogranites in the Everest-Makalu region of eastern Nepal will be conducted. This project is unique, compared to previous studies of leucogranite petrogenesis, in that it features high-resolution geochronology designed to explore the rate and episodicity of the melting process. Since the successful dating of leucogranites relies on U-Th-Pb analyses of accessory minerals (zircon, monazite, xenotime, and uraninite), one key to understanding leucogranites is understanding the behavior of accessory minerals during the anatectic process. This requires direct and continual feedback between experimental studies and field/analytical studies of geologic examples. The experimental component of this proposal builds on current research by Watson and associates at the Rensselaer Polytechnic Institute by focusing on xenotime solubility in granitic melts.