9317105 Ayers This research will involve experiments that identify the factors which determine HFSE mobility in the mantle beneath island arcs, specifically during metasomatism of the source region of island arc basalts by slab-derived fluids. The mobility of HFSE in hydrothermal systems depends on the stability of HFSE host minerals and their solubility in the aqueous fluid phase. Hydrothermal phase equilibria experiments at 1.5-2.5 GPa and 800-1100oC at known oxygen fugacities will allow identification of stable HFSE hosts in a peridotite (mantle wedge) and a basalt (subducted slab) composition doped with Ti and Zr. Single-crystal aqueous solubility experiments of HFSE host minerals made as a function of P, T, and fluid composition will identify conditions that promote HFSE mobility.
