Glycerol ether biomarkers and their carbon isotopic compositions in a cold seep carbonate chimney from the Shenhu area, northern South China Sea  

作　　者：GE Lu JIANG ShaoYong YANG Tao YANG JingHong WU NengYou ZHANG GuangXue LIU Jian 

机构地区：[1]State Key Laboratory for Mineral Deposits Research and Center for Marine Geochemistry Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, China [2]Guangzhou Marine Geologwal Survey, Guangzhou 510760, China

出　　处：《Chinese Science Bulletin》2011年第16期1700-1707,共8页

基　　金：supported by the National Natural Science Foundation of China (40773029, 40903002 and 40772073);the National Basic Research Program of China (2009- CB219506)

摘　　要：At modern cold seeps,the anaerobic oxidation of methane(AOM)is the dominant pathway for methane consumption in marine sediments.AOM,which is mediated by a consortium of methane oxidizing archaea and sulfate reducing bacteria,is proposed to be responsible for authigenic carbonate formation.A methane-derived carbonate chimney was collected from the Shenhu area, northern South China Sea.The membrane lipids and their very low carbon isotopic compositions(?115‰to?104‰)in the Shenhu chimney suggest the presence of an AOM process.Three specific archaeal and bacterial biomarkers were detected,including Ar,DAGE 1f,and monocyclic MDGD.Their strongly depleted??13C values(?115‰to?104‰),which are lower than those of the normal marine lipids in sediments,reveal biogenic methane as their origin.The carbonate deposits exhibiting a chimney structure indicate that a vigorous methane-rich fluid expulsion may have occurred at the seafloor.We propose that the decomposition of gas hydrates at depth is the likely cause of seepage and cold seep carbonate formation in the Shenhu area.At modem cold seeps, the anaerobic oxidation of methane （AOM） is the dominant pathway for methane consumption in marine sediments. AOM, which is mediated by a consortium of methane oxidizing archaea and sulfate reducing bacteria, is proposed to be responsible for authigenic carbonate formation. A methane-derived carbonate chimney was collected from the Shenhu area, not^hem South China Sea. The membrane lipids and their very low carbon isotopic compositions （-115%o to -104%o） in the Shenhu chimney suggest the presence of an AOM process. Three specific archaeal and bacterial biomarkers were detected, including Ar, DAGE If, and monocyclic MDGD. Their strongly depleted δ13C values （-115‰ to -104‰）, which are lower than those of the normal marine lipids in sediments, reveal biogenic methane as their origin. The carbonate deposits exhibiting a chimney structure indicate that a vigorous methane-rich fluid expulsion may have occurred at the seafloor. We propose that the decomposition of gas hydrates at depth is the likely cause of seepage and cold seep carbonate formation in the Shenhu area.

关 键 词：碳同位素组成 生物标志物 自生碳酸盐 烟囱结构 中国南海 冷泉 南海北部 甘油醚 

分 类 号：P597[天文地球—地球化学]