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<p>Subduction zones, linking the surface and deep carbon reservoirs, significantly affect the Earth’s long-term climate change and habitability. The subducting slabs undergo decarbonation with increasing pressure and temperature, during which partial carbon mobilizes out of the slab and returns to the surface by arc volcanism or degassing, while the residual carbon continues to descend to greater depths in the mantle. The estimated carbon influx at subduction zones depends strongly on the calculation model, with contributions from sediments ranging from 15 to 60 Mt C/yr, altered ocean basalts from 18 to 61 Mt C/yr, and serpentinized perdotites from 1.3 to 36 Mt C/yr. The carbon influx varies in space and time. Carbon removal from subducting slab occurs through metamorphic reactions, carbonate dissolution, diapirism, hydrocarbon formation and melting. Among these decarbonation mechanisms, diapirism and slab meting play a decisive role in dictating the depth at which surface carbonates can subduct. Specifically, diapirism may restrict sedimentary carbonates at shallow depths (&lt;200 km), while slab melting exhausts all carbonates from the altered ocean crust near transition zones (410–660 km). Consequently, a mechanism enabling surface carbonates to reach the lower mantle, <i>i.e.</i>, ultra-deep carbon cycle, is required to be in accordance with observations by natural samples.</p>

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Carbon Input and Output at Subduction Zones: Review and Prospect

  • 期刊论文

  • 发表日期：

    2025年5月8日

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  • Wei Chen,
  • Guoliang Zhang

摘要

Subduction zones, linking the surface and deep carbon reservoirs, significantly affect the Earth’s long-term climate change and habitability. The subducting slabs undergo decarbonation with increasing pressure and temperature, during which partial carbon mobilizes out of the slab and returns to the surface by arc volcanism or degassing, while the residual carbon continues to descend to greater depths in the mantle. The estimated carbon influx at subduction zones depends strongly on the calculation model, with contributions from sediments ranging from 15 to 60 Mt C/yr, altered ocean basalts from 18 to 61 Mt C/yr, and serpentinized perdotites from 1.3 to 36 Mt C/yr. The carbon influx varies in space and time. Carbon removal from subducting slab occurs through metamorphic reactions, carbonate dissolution, diapirism, hydrocarbon formation and melting. Among these decarbonation mechanisms, diapirism and slab meting play a decisive role in dictating the depth at which surface carbonates can subduct. Specifically, diapirism may restrict sedimentary carbonates at shallow depths (<200 km), while slab melting exhausts all carbonates from the altered ocean crust near transition zones (410–660 km). Consequently, a mechanism enabling surface carbonates to reach the lower mantle, i.e., ultra-deep carbon cycle, is required to be in accordance with observations by natural samples.