Decoupling of inorganic and organic carbon during slab mantle devolatilisation

Bouilhol, P.; Debret, B.; Inglis, E.C.; Warembourg, M.; Grocolas, T.; Rigaudier, T.; Villeneuve, J.; Burton, K.W.

Abstract

Serpentinites are an important sink for both inorganic and organic carbon, and their behavior during subduction is thought to play a fundamental role in the global cycling of carbon. Here we show that fluid-derived veins are preserved within the Zermatt-Saas ultra-high pressure serpentinites providing key evidence for carbonate mobility during serpentinite devolatilisation. We show through the O, C, and Sr isotope analyses of vein minerals and the host serpentinites that about 90% of the meta-serpentinite inorganic carbon is remobilized during slab devolatilisation. In contrast, graphite-like carbonaceous compounds remain trapped within the host rock as inclusions within metamorphic olivine while the bulk elemental and isotope composition of organic carbon remains relatively unchanged during the subduction process. This shows a decoupling behavior of carbon during serpentinite dehydration in subduction zones. This process will therefore facilitate the transfer of inorganic carbon to the mantle wedge and the preferential slab sequestration of organic carbon en route to the deep mantle.

Citation

Bouilhol, P., Debret, B., Inglis, E., Warembourg, M., Grocolas, T., Rigaudier, T., …Burton, K. (2022). Decoupling of inorganic and organic carbon during slab mantle devolatilisation. Nature Communications, 13(1), Article 308. https://doi.org/10.1038/s41467-022-27970-0

• Journal Article Type: Article
• Acceptance Date: Dec 10, 2021
• Online Publication Date: Jan 14, 2022
• Publication Date: 2022
• Deposit Date: Feb 18, 2022
• Publicly Available Date: Feb 18, 2022
• Journal: Nature Communications
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• Volume: 13
• Issue: 1
• Article Number: 308
• DOI: https://doi.org/10.1038/s41467-022-27970-0