地球深部脱碳过程研究评述  

Outgassing processes of carbon in deep Earth:A review

作　　者：李卓骐 许成[1,2] 韦春婉 LI Zhuoqi;XU Cheng;WEI Chunwan(Ministry of Education Key Laboratory of Orogenic Belts and Crustal Evolution,School of Earth and Space Sciences,Peking University,Beijing 100871,China;Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources by the Province and Ministry,College of Earth Sciences,Guilin University of Technology,Guilin 541006,China)

机构地区：[1]北京大学地球与空间科学学院造山带与地壳演化教育部重点实验室,北京100871 [2]桂林理工大学地球科学学院有色金属矿产勘查与资源高效利用省部共建协同创新中心,广西桂林541006

出　　处：《地学前缘》2024年第6期304-319,共16页Earth Science Frontiers

基　　金：国家自然科学基金项目(92162219);广西自然科学基金项目(Guike AB22035045)。

摘　　要：地球深部是一个巨大的碳库,含有地球98%以上的碳。在上地幔顶部,碳的主要存在形式是碳酸盐与CO_(2)。在一定的温度和压力条件下,它们可以降低地幔岩的固相线,参与地幔熔融过程,形成含碳的硅酸盐熔体或者碳酸盐熔体。含碳的熔流体是岩石圈地幔中碳迁移的重要形式,也是地球深源碳向地表释放的直接载体。碳酸盐熔体与碳酸盐化硅酸盐熔体在地幔中迁移、上侵过程中可能与橄榄岩发生反应,熔体分解并释放出CO_(2)。在地壳阶段,除了火山作用导致的脱气外,含碳熔体在上侵的过程中,减压导致熔体中CO_(2)溶解度降低,或者熔体与地壳岩石之间的脱碳反应也是CO_(2)释放的重要途径。地表碳可以随板块俯冲等作用进入地球深部,该过程与深源碳释放构成的深部碳循环过程是影响地球历史大气中碳含量与气候变化的重要因素。在现代冷板块俯冲过程中,碳释放的主要形式是俯冲板片释放的流体对板片中碳的溶解和迁移,大部分的俯冲碳能够进入地球深度。深部脱碳过程的复杂性使当前对地史时期深部碳释放的途径与对应的通量仍有争议,对不同脱碳作用的综合研究是进一步厘清地史时期碳释放的重要依据。因此,本文系统地总结了深部碳循环过程中不同脱碳作用与其识别标志,并以华北克拉通东缘中生代脱碳过程为例,探讨了深源碳释放对于古环境变化的指示意义。The Earth’s deep interior is a massive carbon reservoir,containing more than 98%of the Earth’s carbon.In the uppermost mantle,carbon primarily exists as carbonates and CO_(2).Under certain temperature and pressure conditions,they can lower the solidus of mantle rocks,participating in mantle melting processes and forming carbon-bearing silicate or carbonate melts.Carbon-bearing melts are an important form of carbon migration in the lithospheric mantle and are the direct carrier of deep-sourced carbon release to the surface.During the migration and upwelling of carbonate melts and carbonated silicate melts in the mantle,they may react with olivine,causing melt decomposition and releasing CO_(2).In the crustal stage,in addition to degassing caused by volcanic activity,during the upwelling of carbon-bearing melts,pressure reduction leads to a decrease in the solubility of CO_(2)in the melt,or decarbonation reactions between the melt and crustal rocks are also important pathways for CO_(2)release.Surface carbon can enter the Earth’s deep interior through plate subduction and other processes.This process,together with the release of deep-sourced carbon,constitutes a deep carbon cycle that significantly influences the carbon content in the Earth’s historical atmosphere and climate change.In modern cold plate subduction,the main form of carbon release is the dissolution and migration of carbon in the slab by fluids released from the subducting slab,and most of the subducted carbon can enter the deep Earth.The complexity of deep decarbonation processes makes the pathways and corresponding fluxes of deep carbon release during geological history still controversial.Comprehensive research on different decarbonation processes is an important basis for further clarifying carbon release during geological history.Therefore,this paper systematically summarizes the different decarbonation processes and their identification markers in the deep carbon cycle,and takes the Mesozoic decarbonation process in the eastern margin o

关 键 词：脱碳 地球深部 地幔去气 地壳去气 俯冲带脱碳 

分 类 号：P542.5[天文地球—构造地质学] P595[天文地球—地质学]