The oxidation state of Fe in basalts from the Mariana subduction system

Arc basalts are more oxidized than mid ocean ridge basalts (MORB), but whether this oxidized signature arises from differentiation processes in the Earth's crust or inherited from the mantle source is unresolved. I present major and trace element, S and Cl concentrations, volatile concentrations and Fe3+/TFe ratios measured on basaltic glasses from the Mariana subduction system in order to test between these hypotheses. The data are used to understand the relationship between subduction and the generation of oxidized magmas, as well as the implications that this relationship has for the mantle in other tectonic settings.