Carbonation of subduction-zone serpentinite (high-pressure ophicarbonate; Ligurian Western Alps) and implications for the deep carbon cycling

- Serpentinite plays a pivotal role in the deep subduction-zone carbon cycle.
- In dehydrating at 2 GPa-550 °C, it supplies H2O to carbonate rocks, enhancing decarbonation and release of CO2.
- Back-reaction of serpentinite with the COH-fluid promotes carbonation and C sequestration.
- This could result in retention of ∼0.5 to ∼5 Mt C/yr in slab and mantle wedge serpentinite.