Subduction fluxes through geologic time

Geochemical models have convincingly demonstrated that sediment and altered oceanic crust must be recycled into the mantle through subduction zones. These ‘subduction factories’ use these components, along with molten mantle, to create arc magmas. The ‘residue’ from this process is recycled into the mantle and has a modified chemical and mineralogical composition. The altered oceanic crust input function in the current plate tectonic cycle seems to be relatively constant in composition, but the chemical compositions of the sediment fluxes into subduction zones vary widely and control many of the end-member compositions of arc magmas. They must also control the compositions of fluids and gases derived from these magmas and ultimately ore-deposition and atmospheric fluxes associated with arc volcanoes.