俯冲板片的脱碳机制及通量估算:问题与进展SCIEI北大核心CSCD

地球98%以上的碳赋存在地球深部地幔和地核中。地球深部储库(地幔和地核)中的碳以各类岩浆作用释放到地表,而地球表层系统(大气圈、水圈、生物圈)中的碳又可以伴随板块俯冲作用进入地球深部地幔。然而俯冲过程中不同的脱碳机制会将俯冲板片中部分乃至全部碳带出板片,而后经由岛弧岩浆作用、流体扩散作用等途径返回地表。因此,板片俯冲过程中的脱碳机制及其通量深刻地影响了地质时间尺度中地表系统的二氧化碳浓度,进而改变地球的宜居性。本文总结了目前主流观点认可的五种俯冲板片脱碳机制:变质反应脱碳、流体溶解脱碳、熔融脱碳、底辟脱碳和氧化还原脱碳。另一方面,目前对于俯冲板片各种脱碳机制对应的脱碳效率还有很大的争议,因此本文进一步梳理了板片俯冲过程中不同脱碳机制相关的通量估算的研究进展与存在的问题,建议将来综合多种方法对比研究俯冲带碳循环问题,以期在俯冲带深部碳循环过程和通量方面取得突破性进展。

Carbon releasing mechanisms and flux estimation in subducting slabs:Problems and progress

More than 98% of the global carbon is stored in the Earth''s mantle and the core. The carbon in the Earth''s interior could release to the surface by various magmatism, while the carbon on the surface can enter the Earth''s interior along with the subduction of plates. Subducting slabs cannot carry all the stored carbon into the deep Earth. Different decarbonization mechanisms will release carbon out of the slabs during the subducting process. The carbon releasing mechanism and the flux in the subduction zones have profound impacts on the concentration of CO₂ in the Earth''s surface system which could change the habitability of the Earth. Here we summarized five decarbonization mechanisms: metamorphic decarbonization, carbonate dissolution, carbonate melting, sediments diapirism, and redox reaction. On the other hand, the carbon releasing fluxes in the subduction zones are still controversial at present. Therefore, we also reviewed the research progress and the problems for decarbonization mechanism and their flux estimation in the subduction zones to inspire new research methods to make a breakthrough of the deep carbon cycle in subduction zones in the future.