Experimental Geochemical Studies of Solid-Melt Mass Transport Processes Beneath Mid-Ocean Ridges

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9731506 Grove This work will involve experimental studies aimed at understanding the conditions and time scales of mantle melting processes beneath active ocean spreading centers. The experiments will determine diffusion rates of rare earth, high field strength and large-ion lithophile elements in garnet and high-Ca clinopyroxene at elevated pressure (1 to 3 GPa) and temperature (1250oC - 1500oC) conditions. These are the conditions relevant for mantle melting beneath mid-ocean ridges. The results of the experiments will be used to estimate the time scales and styles of melt generation processes. To infer the nature of the melting processes we will analyze the element abundances in the products of melting (mid-ocean ridge basalts) and the solid residues left behind after melt extraction (abyssal peridotites). The experimental results and the element abundances in the natural samples will then be used as input to models of melt production. The primary unknown in these melting models is the solid state diffusion rates for the elements, which will be provided by the experiments.