藏南羊应中新世火山区温室气体的释放通量与成因

Fluxes and origin of greenhouse gases emitting from Cenozoic volcanic fields at continental subduction zone have become an important but open issue. As an unique geological unit at the convergent boundary between the Indian and Asian plates, the Tibetan Plateau is now emitting huge amount of greenhouse gases to the atmosphere. This proposal will focus on the fluxes of greenhouse gases released by Yangying volcanic field (YVF) in southern Tibet, aiming to quantitatively estimate scale of greenhouses (soil micro-seepage and bubbling gases) of the YVF, which could provide the scientific basic data for geological carbon budget of Cenozoic volcanic fields at continental subduction zone and also for the international climate negotiation of our country in future. Origin and evolution of the volcanic gases will be investigated by combination of geochemical characteristics of volcanic gases and volcanic rocks. Furthermore, the relationship between release of greenhouse gases of the YVF and northward subduction of the Indian continental lithosphere will also be discussed.

大陆俯冲带新生代火山区温室气体的释放特征、规模及其成因机制已经成为当今学术界悬而未决的重要研究课题。作为地球上独一无二的地质单元，青藏高原是印度-亚洲大陆俯冲带的重要组成部分，目前正在向大气圈释放巨量的温室气体。本项目拟选择藏南羊应中新世火山区开展土壤微渗漏和温泉温室气体释放通量的测量与估算工作，为大陆俯冲带新生代火山区温室气体释放规模提供基础数据，同时也为我国的国际气候谈判博弈提供地质源碳排放的科学依据。结合气体地球化学与岩石地球化学方法，探讨羊应火山气体的来源与演化机制及其对印度大陆北向俯冲动力学过程的指示意义。

项目实施期间，所有研究计划均顺利执行并完成。通过广泛而深入的地质调查，成功引入国际上本领域目前最先进的技术方法，对羊应火山地热区开展详细的温室气体释放通量测量(土壤微渗漏CO2平均释放通量为99gm-2d-1，每年向大气释放的CO2总量为5.4×104吨)。通过气体和岩石地球化学相结合开展模拟计算，羊应火山地热区的气体是印度大陆板块俯冲引起的富集地幔楔熔融发生演化的产物，而其释放的碳，主要来源于拉萨地壳的沉积碳酸盐岩。并将该研究方法其进一步推广到谷露-亚东的其它14个水热活动区，获得了重要的碳排放数据和温泉逸出气体样品，为探讨大陆俯冲带碳排放成因提供研究资料。现有调查研究结果表明，我国藏南新生代火山地热区具有释放温室气体的巨大潜力。作为全球独一无二的大陆俯冲带，青藏高原是我国重要的地质碳排放源，其碳排放规模与成因值得继续进行系统而深入的专门研究。