Subduction-Related Hydration and Sulfur Metasomatism in the Mariana forearc mantle wedge:.
 
Hydration and serpentinization of the mantle wedge during subduction in the Mariana forearc has resulted in protrusion of serpentintite seamounts at the surface (Fig 1).  At these sites, serpentite formed at depth is exposed at the surface and fluids derived from the subducting slab, some 30 km below, vent from these seamounts.  Study of the sulfide and oxide mineralogy and the contents and isotopic compositions of sulfur in the serpentinites will help constrain the conditions of serpentinization at depth, and provide important data to understand fluxes of slufr from the slab to arc volcanics (e.g., Alt et al., 1993).