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在现代冷泉体系中,甲烷缺氧氧化(AOM)是海洋沉积物中甲烷消耗的主要途径.AOM以微生物,即甲烷氧化古细菌和硫酸盐还原细菌为媒介氧化甲烷,并还原硫酸根,同时促进冷泉碳酸盐岩的形成.东沙海区冷泉碳酸盐岩中的生物标志化合物为烃类和醚类异戊二烯.与东沙海区不同的是,神狐海区同时存在甲烷缺氧氧化古细菌相关和硫酸盐还原细菌相关的两大类生物标志化合物.在样品中发现了3种AOM标志化合物:含双植烷链的甘油醚(archaeol)、非类异戊二烯结构的二烷基甘油醚(DAGE1f)和单环二植基甘油二醚(单环MDGD).这些化合物具有强烈亏损的δ13C值(δ13C值在-15‰~-104‰之间),明显低于一般海相沉积物中脂类的δ13C值,充分表明其生物成因的甲烷来源.神狐海区烟囱状的冷泉碳酸盐岩同时反映了该海区曾经发生过持续的富甲烷流体的喷流活动,推测天然气水合物的分解可能是该海区烃类活动的一个重要原因.
In modern cold-spring systems, methane anaerobic oxidation (AOM) is a major source of methane depletion in marine sediments, and AOM oxidizes methane and reduces sulfate with the help of microorganisms, archaeal methanotrophs and sulfate-reducing bacteria, The formation of cold spring carbonate rocks.The biomarker compounds in cold spring carbonate rocks in Dongshahai area are hydrocarbons and isoprenoids.Different from Dongsha sea area, Two major classes of biomarker compounds associated with sulfate-reducing bacteria were identified in the samples: Three AOM-labeled compounds were found in the sample: archaeol with a double phytane chain, dialkylglycerol with a non-isoprenoid structure (DAGE1f) and monocyclic di-glycerin diethylether (monocyclic MDGD). These compounds have strongly depleted δ13C values (δ13C values between -15 ‰ and -104 ‰), which are significantly lower than those of typical marine sediments The δ13C values of lipids fully indicate the biogenic origin of methane. The chimney-like cold spring carbonate rocks in Shenhu sea area also reflect the continuous jet flow of methane-rich fluid in the sea area, suggesting that the decomposition of natural gas hydrate It may be that Sea area hydrocarbon activity is an important reason.