Experimental Investigations of Melting Processes in the Subcontinental Mantle

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GroveEAR-0073766The research will investigate the processes that lead to the generation of magmas in the earth's upper mantle. The methods of experimental petrology will be used and melting experiments will be performed at elevated temperature (1200 - 1700 oC) and pressure (2 - 5 GPa) under anhydrous and H2O-undersaturated conditions. Samples used for the experiments will be metasomatized mantle analog compositions and natural basalt compositions. Two types of experiments will be performed. The first set of experiments will produce melts saturated with mantle minerals (olivine, orthopyroxene, clinopyroxene and garnet) and the variation in composition of the melt will be used to develop predictive analytic models for the conditions of melt generation in the subcontinental mantle. The second set of experiments will use selected naturally occurring basaltic magmas from a range of continental tectonic settings (the Tibetan Plateau, Sierra Nevada and Mexican back arc) and will determine the conditions of melt generation in these settings. From these results models will be developed that evaluate the controls of pressure, temperature, H2O and variations in mantle bulk composition on mantle melting reactions. The experiments and models will provide constraints on the processes of stabilization of sub-continental lithosphere, mantle flow and melting beneath continents and the influence of the flux of volatiles through the mantle.