【作者】 蒋少涌； 杨涛； 葛璐； 凌洪飞； 杨競红； 吴能友； 陈道华； 刘坚；

【Author】 JIANG Shaoyong~1) YANG Tao~1) GE Lu~1) LING Hongfei~1) YANG Jinghong~1) WU Nengyou~2) CHEN Daohua~1,2) LIU Jian~2) 1)State Key Laboratory for Mineral Deposits Research,Deportment of Earth Sciences,and Center for Marine Geochemistry Research.Nanjing University,Nanjing,Jiangsu,210093;2)Guangzhou Marine Geological Survey,Guangzhou,Guangdong,510760

【机构】 南京大学地球科学系成矿作用同家重点实验室南京大学海洋地球化学研究中心； 广州海洋地质调查局；

【摘要】 硫酸根离子(SO₄^2-)是海洋沉积物孔隙水中的重要组分之一。硫酸盐还原菌利用孔隙水中SO₄^2-作为氧化剂氧化沉积物中有机质或甲烷,造成孔隙水中SO₄^2-离子浓度降低,同时使溶解在孔隙水中CO₂的碳同位素组成降低。研究表明,在有天然气水合物出现的地区,强烈的甲烷缺氧氧化作用使孔隙水SO₄^2-浓度急剧下降,表现为海底沉积物中硫酸盐-甲烷界面（SMI）较浅。如布莱克海台区,SMI 界面为5.1～23.9m,界面附近溶解于孔隙水中CO₂的δ¹³C 值低达-39‰。笔者发现南海北部海区几个站位具有类似于布莱克海台区的较浅的SMI 界面（7.5～17.2m）和极低的δ¹³C 值（-29‰）,结合其他地质、地球物理和地球化学证据,推测这些站位处可能赋存有天然气水合物,值得开展进一步详查工作。更多还原

【Abstract】 Being an important constituent in pore water of marine sediments,sulfate（SO₄²）acts as an oxidation agent involved inorganic matter or methane oxidation reactions induced by microbial activity.These chemical reactions deplete sulfate within pore wa-ters of the sulfate reduction zone,and also decrease carbon isotopic compositions of dissolved CO₂.It is demonstrated that in gas hy-drate areas such as the Blake Ridge,the strong anaerobic methane oxidation reaction produces linear and steeper sulfate gradients withshallow SMI depths.In the Blake Ridge,the SMI depths are between 5.1m and 23.9m,with δ¹³C values as negative as-39‰.It is found that several sites in the South China Sea also show shallow SMI depths（7.5m～17.2m）and low δ¹³C values（-29‰,）,similar to characteristics of the Blake Ridge.Combined with other geological,geophysical and geochemical evidence,it is consideredthat these sites may have great potential for gas hydrate accumulation at depths and therefore deserve further detailed exploration.更多还原