Arc magmas oxidized by water dissociation and hydrogen incorporation in orthopyroxene

Elevated H2O concentrations and oxygen fugacities are two fundamental properties that distinguish magmas formed in subduction zones from new crust generated at mid-ocean ridges. However, the mechanism of magma oxidation and how it relates to the increase in H2O remain unclear. In this study, we used infrared spectroscopy of mantle wedge orthopyroxene to trace the temporal and spatial evolution of oxygen fugacity during the transport of hydrous...