南海北部陆坡西部海域“海马”冷泉甲烷渗漏及其海底表征

2015年3月"海马"号遥控无人潜水器(ROV)在南海北部陆坡西部海域首次发现活动冷泉,并命名为"海马"冷泉,此后中国地质调查局广州海洋地质调查局先后组织了3个航次,对"海马"冷泉开展进一步勘查和研究。本次研究在综合分析4个航次调查数据的基础上,初步阐述"海马"冷泉的分布范围、地形地貌、生物群落、自生碳酸盐岩和流体活动等特征。总体而言,"海马"冷泉区地势平缓,气体渗漏现象非常发育,是以CH4为主要气体渗漏形成的活动冷泉区,且气体渗漏活动具有时空迁移性。气体碳同位素组成表明,海马冷泉区的CH4为混合成因气,且以微生物成因为主;"海马"冷泉区发育有多种类型的化能自养冷泉生物群落,冷泉区种类丰富,目前已报道了多个冷泉生物新种。这些发现为研究南海北部陆坡西部海域天然气水合物分解及其环境效应、冷泉生物生命起源与演化和南海与印度洋及太平洋物种迁移贯通等科学问题提供重要依据。

Seafloor geology and geochemistry characteristic of methane seepage of the “Haima” cold seep,northwestern slope of the South China Sea

In March 2015,a newly active cold seep was discovered using the "Haima" remotely operated vehicle(ROV) in the northwestern slope of the South China Sea(SCS);three additional cruises were organized to further investigate the "Haima" cold seep after it was discovered.Based on the data obtained during the four expeditions,we preliminarily studied the distribution,seafloor topography,biological community,authigenic carbonate rocks,and fluid activities of the cold seep.In general,the terrain of the "Haima" cold seep area is a flat,wildly developing the gas seepage structure,which is an active cold seep area mainly formed by time-space migrated methane leakage.The carbon isotope composition of methane shows that the methane in the "Haima" cold seep is characterized by mixed,mainly microbial genetics.There are many types of chemoautotrophic cold seep communities in the "Haima" cold seep area and many new species have been reported.These findings provide an important basis for the study of natural gas hydrate decomposition and its environmental effects,the origin and evolution of cold seep biological life,as well as species migration between the SCS and the Indian Ocean and the Pacific Ocean.