Mobilization of isotopically heavy sulfur during serpentinite subduction.

Primitive arc magmas are more oxidized and enriched in sulfur-34 (S) compared to mid-ocean ridge basalts. These findings have been linked to the addition of slab-derived volatiles, particularly sulfate, to arc magmas. However, the oxidation state of sulfur in slab fluids and the mechanisms of sulfur transfer in the slab remain inconclusive.