Serpentinites are hydrated (< 13 wt%) olivine-rich ultramafic rocks, and are abundant on the sea floor, in mantle wedges, and along major strike-slip faults. Serpentinites are particularly abundant in oceanic plates formed at slow spreading ridges, and are over 25 % of exposed ocean floor. They incorporate sea water and fluid-mobile elements and transport them from ridges to subduction zones. In subduction zones, the mechanically weak and "slippery" serpentinites facilitate the subduction of the incoming plate by lowering the friction between two plates, and form an aseismic zone. Serpentinites also form in mantle wedges, as the result of water released from slabs. These serpentinites are buoyant compared to anhydrous rocks, and commonly protrude to the surface along major strike-slip faults, and diapirs, such as the Mariana serpeninite diapirs.


Serpentinites are stable under a wide variety of settings including the upper mantle. This results in them acting as an important storage of water and fluid-mobile elements (FME) in the mantle. Eventual dehydration of serpentinites releases them to the hot interior of mantle wedge, triggering the arc volcanism. Thus, serpentinites play a major role in the recycling of elements from the surface to the mantle, and back to the surface via arc volcanoes.