超基性岩的蛇纹石化作用生成大量无机成因的甲烷，为大洋海底形成甲烷水合物提供必要的气源，最近在Fram海峡超慢速扩张脊发现有蛇纹石化甲烷水合物的发育。马里亚纳海沟弧前海底发育规模巨大的蛇纹岩泥火山，其顶部海底渗漏进入水体的流体富含甲烷，温度和压力符合甲烷水合物形成的温压条件，蛇纹岩泥火山海域无机成因甲烷是否能形成水合物、潜力如何尚不清楚。本项目以马里亚纳蛇纹岩泥火山已有的深潜、大洋钻探计划和国际大洋发现计划钻探资料为基础，根据渗漏流体和蛇纹岩泥火山沉积物孔隙水的地球化学特征及海底温度、地温梯度与水深等，建立适合蛇纹岩泥火山形成甲烷水合物的热力学相平衡模型；以硫酸根等孔隙水地球化学等参数，反演甲烷的供给通量，建立蛇纹岩泥火山甲烷水合物生成的动力学模型，模拟甲烷水合物生成过程和分布状态，评价甲烷水合物的资源量潜力，为大洋蛇纹岩化形成的甲烷水合物调查和勘探提供理论基础。

Serpentinization of ultramafic rocks could generate large amounts of abiotic methane, which would provide necessary gases for methane hydrate formation under the seafloor. Numerous serpentine mud volcanoes in large size occurred in the forearc regions of Mariana trench. The seepage fluids are enriched in abiotic methane on the top of serpentine mud volcanoes, and the pressure and the temperature beneath the seafloor are thermodynamically in methane hydrate stabilization zone. However, little is known about whether methane hydrate could form at the Mariana serpentine mud volcanoes, and its occurrence and resources prospect is not clear. This proposal intends to establish thermodynamic equilibrium model for Mariana serpentine mud volcanoes based on the geochemistry of pore water and seepage fluids, and temperatures, geothermal gradient and water depths by ODP drilling and submersible survey. Methane flux and the oxidation rate of methane would be investigated by geochemical parameters of pore water, such as concentration of sulfate. The dynamic methane hydrate accumulation model at serpentine mud volcanoes would be established and used to simulate the generation of methane hydrate and its occurrence in subsurface. Finally, amount of gas hydrate resourcehs will be evaluated. This research would contribute to basal theoretical support for the investigation and exploration of methane hydrate in ocean seafloor.