The oxidation state, and sulfur and Cu contents of arc magmas: implications for metallogeny

Thus, three components, [S], [H2O], and fO2 work together throughout subduction and arc magmatic processes to transport chalcophile and siderophile metals from the mantle into the upper crust, where they may be concentrated by hydrothermal processes to form ore deposits. These processes are far from 100% efficient, and metals (especially highly siderophile elements such as Au and PGE) may be left behind at various stages of the passage of arc magmas through the lithosphere, where they may form potentially metalliferous source rocks for partial melts and subsequent magmatic-hydrothermal ore deposits generated during later tectonomagmatic events.