Program > Browse abstracts by speaker > Wang Yu

Subduction transports significant amounts of carbonates into the reduced, Fe0-bearing sublithospheric mantle (>250 km), leading to heterogeneous mantle redox states and sublithospheric diamond formation beneath cratons. To elucidate the driving force of mantle redox variation, we performed reaction experiments between carbonatite melt and Fe0-bearing peridotite at 9-21 GPa under varying redox conditions. Comparing our results with sublithospheric diamond inclusions, we find that majorite and ferropericlase inclusions from the Amazonia Craton reflect a predominantly reduced, non-plume mantle environment, while majorites from the Kaapvaal Craton indicate a fully oxidized plume setting. In non-plume environments, carbonatite melts released from subducting slabs are progressively consumed until fully frozen into reduced, inactive carbon. Attachment of these reduced materials to the cratonic keel further enhances craton stability. In plume environments, carbonatite melts surpass the redox buffering capacity of Fe0, leading to a fully oxidized, CO2-rich melt-bearing mantle. Impregnation of these melts into the lithosphere weakens the cratonic keel, resulting in lithosphere delamination, surface uplift and widespread volcanism.