[SGC49-11] Highly siderophile element mobility during serpentinization of forearc mantle peridotite
Keywords:highly sideophile element, mantle peridotite, serpentinization
Here we investigated uplifted mantle section of Timor-Tanimbar ophiolite in eastern Indonesia as a best example to characterize serpentinization in mantle wedge, since geological occurrence suggests this Miocene-aged ophiolite extends neighboring pre-emplaced forearc marginal basins. We performed whole-rock concentration analyses of major, trace and highly siderophile elements (HSEs) for extremely fresh peridotites and strongly altered serpentinites exposed in Moa island. Our results demonstrate that element mobility associated with infiltration of slab-derived fluids into peridotites in the mantle wedge are characterized by broad correlations between uptake of fluid mobile elements (e.g. Sr, Pb, LREE) and release of HSEs (up to 95%), which could be controlled by degree of fluid-peridotite reactions under oxidizing conditions. This result suggests that oxygen fugacities play an important roles on HSE mobility associated with sulfide breakdown, and serpentinization in different tectonic settings should be considered separately.