| 海洋沉积物孔隙水硫酸盐浓度和碳同位素对天然气水合物的指示 |
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| 引用本文：蒋少涌,杨涛,葛璐,凌洪飞,杨競红,吴能友,陈道华,刘坚.2005.海洋沉积物孔隙水硫酸盐浓度和碳同位素对天然气水合物的指示[J].地球学报,26(z1):190-191. |
| DOI：10.3975/cagsb.2005.s1.60 |
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| 中文摘要:硫酸根离子（SO42－）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SO42－作为氧化剂氧化沉积物中有机质或甲烷，造成孔隙水中SO42－离子浓度降代，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SO42－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，界面附近深解于孔隙水中CO2的δ13C值低达－39％。笔者发现南海北京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。 |
| 中文关键词:硫酸盐浓度梯度 碳同位素 孔隙水 天然气水合物 |
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| Sulfate Concentrations and Carbon Isotopic Compositions as Indicators of Marine Gas Hydrates |
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| Abstract:Beiing an important constituent in pore water of marine sediments, sulfate （SO42－） acts as an oxidation agent involved in organic matter or methane oxidation reactions induced by microbial activity. These chemical reactions deplete sulfate within pore waters of the sulfate reduction zone, and also decrease carbon isotopic compositions of dissolved CO2. It is demonstrated that in gas hydrate areas such as the Blake Ridge, the strong andaerobic methane oxidation reaction produces linear and steeper sulfate gradients with shallow SMI depths. In the Blake Ridge, the SMI depths are between 5.1 m 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 considered that these sites may have great potential for gas hydrate accumulation at depths and therefore deserve furthe detailed exploration. |
| keywords:sulfate gradients carbon isotopes pore water gas hydrate |
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