海底蛇纹岩泥火山及其流体活动和自养生物群发育于俯冲带弧前海底，因其与无机成因甲烷、地球生命起源和深海环境等重大科学问题有关，而受到越来越多的关注。马里亚纳海沟弧前蛇纹岩泥火山是现代海底的实例，古代的记录在全球多处被发现，但我国尚未见报导。前人在中国台湾东部利吉混杂岩中发现有大量具有沉积特征的蛇纹岩角砾碎屑岩，其中普遍发育有δ13C值极低的碳酸盐岩脉(δ13C低达-54.5‰ VPDB)，但其成因至今还没有定论。本申请项目拟对利吉混杂岩中蛇纹岩角砾碎屑岩及其伴生碳酸盐岩脉开展野外地质和室内岩石学与地球化学研究，确定蛇纹岩角砾碎屑岩的地质和地球化学特征、脉状碳酸盐岩形成的流体特征及碳源，寻找蛇纹岩泥火山海底流体渗漏形成的自生沉积和自养生物化石，回答蛇纹岩角砾碎屑岩是否由海底蛇纹岩泥火山作用形成、伴生碳酸盐岩脉是否与蛇纹岩化过程中无机成因甲烷的微生物氧化有关等关键科学问题。

Serpentinite mud volcanoes at seafloor with associated fluid seepage activities and chemosynthetic biocommunity, occurring in forearc regions of subduction zones, are increasingly getting focused owing to their close relationships with abiogenic methane, the origin of life on Earth, and deep ocean environment. The typical modern active examples at seafloor are Mariana forearc serpentinite mud volcanoes. Their ancient counterparts have been found in many places around the world. However, there are no such reports in China. Numerous serpentinite breccias with sedimentatary characteristics occurred in the forearc Lichi Mélange of eastern Taiwan, China. Carbonates usually occurred as veins in these serpentinites have extremely negative values of δ13C (as low as -54.5‰ VPDB). But, their formation mechanisms are unknown at present. This proposal intends to study the geology, petrography and geochemistry of serpentinite breccias and associated carbonate veins occurred in the Lichi Mélange, to constrain the characteristics of the serpentinite breccias and the parent fluids and the carbon sources of the carbonate veins. Authigenic deposits of fluid seepage and chemosynthetic biocommunity fossils would be investigated, as well. Finally, this proposal will answer the key scientific questions that whether the serpentinite breccias are originated from serpentinite mud volcanoes, and whether the carbonate veins are related to the anaerobic microbial oxidation of abiogenic methane formed during serpentinization.