2025-05-22 中国科学院 (CAS)
Schematic illustration showing the role of slab carbonatite melts on mantle redox states, sublithospheric diamond formation, and craton evolution under nonplume and plume scenarios. (Image by Prof. XU Yigang’s group)
＜関連情報＞
- https://english.cas.cn/newsroom/research_news/earth/202505/t20250520_1044104.shtml
- https://www.science.org/doi/10.1126/sciadv.adu4985
深く沈み込んだ炭素によって引き起こされるマントル酸化還元状態の変動 Variable mantle redox states driven by deeply subducted carbon
Mingdi Gao, Yu Wang, Stephen F. Foley, and Yi-Gang Xu
Science Advances Published:21 May 2025
DOI:https://doi.org/10.1126/sciadv.adu4985
Abstract
Slab subduction transports carbonates into the reduced, metallic iron (Fe0)–bearing sublithospheric mantle (>250 kilometers), leading to heterogeneous mantle redox states and sublithospheric diamond formation beneath cratons. To elucidate the drivers of mantle redox variation, we performed mixed reaction experiments between carbonatite melt and Fe0-bearing peridotite at 9 to 21 gigapascals 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, nonplume mantle environment, while majorites from the Kaapvaal Craton indicate a fully oxidized plume setting. In nonplume environments, carbonatite melts are progressively consumed until fully frozen as reduced carbon. Attachment of these materials to the cratonic keel further enhances craton stability. In plume environments, carbonatite melts surpass the redox buffering capacity of Fe0, leading to an 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.
