Fatty-acids and their δ^(13)C characteristics of seep carbonates from the northern continental slope of Gulf of Mexico  

作　　者：GUAN HongXiang FENG Dong WU NengYou CHEN DuoFu ROBERTS H H WU DaiDai 

机构地区：[1]CAS Key Laboratory of Marginal Sea Geology, State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China [2]CAS Key Lab of Renewable Energy and Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China [3]Graduate University of Chinese Academy of Sciences, Beijing 100049, China [4]Coastal Studies Institute, Louisiana State University, Baton Rouge, LA 70803, USA

出　　处：《Chinese Science Bulletin》2010年第8期730-735,共6页

基　　金：supported by the National Basic Research Program of China (Grant No.2009CB219508);National Natural Science Foundation of China (Grant Nos.40725011 and U0733003);the State Key Laboratory of Organic Geochemistry (Grant No.OGL-200811);Knowledge Innovation Program of Chinese Academy of Sciences (Grant No.KGCX2-YW-805)

摘　　要：Here we reported the fatty-acids and their δ13 C values in seep carbonates collected from Green Canyon lease block 185 (GC 185;Sample GC-F) at upper continental slope (water depth:～540 m),and Alaminos Canyon lease block 645 (GC 645;Sample AC-E) at lower continental slope (water depth:～2200 m) of the Gulf of Mexico.More than thirty kinds of fatty acids were detected in both samples.These fatty acids are maximized at C 16.There is a clear even-over-odd carbon number predominance in carbon number range.The fatty acids are mainly composed of n-fatty acids,iso-/anteiso-fatty acids and terminally branched odd-numbered fatty acids (iso/anteiso).The low δ13 C values (-39.99‰ to -32.36‰) of n-C 12:0,n-C 13:0,i-C 14:0 and n-C 14:0 suggest that they may relate to the chemosynthetic communities at seep sites.The unsaturated fatty acids n-C 18:2 and C 18:1 △9 have the same δ13 C values,they may originate from the Beggiatoa/Thioploca.Unlike other fatty acids,the terminally branched fatty acids (iso/anteiso) show lower δ13 C values (as low as -63.95‰) suggesting a possible relationship to sulfate reducing bacteria,which is common during anaerobic oxidation of methane at seep sites.Here we reported the fatty-acids and their δ^13C values in seep carbonates collected from Green Canyon lease block 185 （GC 185; Sample GC-F） at upper continental slope （water depth： -540 m）, and Alaminos Canyon lease block 645 （GC 645; Sample AC-E） at lower continental slope （water depth： -2200 m） of the Gulf of Mexico. More than thirty kinds of fatty acids were detected in both samples. These fatty acids are maximized at C16. There is a clear even-over-odd carbon number predominance in carbon number range. The fatty acids are mainly composed of n-fatty acids, iso-/anteiso-fatty acids and terminally branched odd-numbered fatty acids （isolanteiso）. The low δ^13C values （-39.99‰ to -32.36‰） of n-C12：0, n-C13：0, i-C14：0 and n-C14：0 suggest that they may relate to the chemosynthetic communities at seep sites. The unsaturated fatty acids n-C18：2 and C18：1A9 have the same δ^13C values, they may originate from the Beggiatoa/Thioploca. Unlike other fatty acids, the terminally branched fatty acids （iso/anteiso） show lower δ^13C values （as low as -63.95%0） suggesting a possible relationship to sulfate reducing bacteria, which is common during anaerobic oxidation of methane at seep sites.

关 键 词：脂肪酸含量 碳酸盐岩 大陆坡 氨基酸 C值 墨西哥湾 渗透 国际标准化组织 

分 类 号：P618.130.2[天文地球—矿床学] TS225.24[天文地球—地质学]