于哲,邓义楠,陈晨,等. 海洋沉积物微量元素地球化学特征对天然气水合物勘探的指示意义[J]. 海洋地质与第四纪地质,2022,42(1): 111-122. DOI: 10.16562/j.cnki.0256-1492.2021040101
引用本文: 于哲,邓义楠,陈晨,等. 海洋沉积物微量元素地球化学特征对天然气水合物勘探的指示意义[J]. 海洋地质与第四纪地质,2022,42(1): 111-122. DOI: 10.16562/j.cnki.0256-1492.2021040101
YU Zhe,DENG Yinan,CHEN Chen,et al. Trace elements geochemistry of marine sediments and its implications for gas hydrate exploration [J]. Marine Geology & Quaternary Geology,2022,42(1):111-122. DOI: 10.16562/j.cnki.0256-1492.2021040101
Citation: YU Zhe,DENG Yinan,CHEN Chen,et al. Trace elements geochemistry of marine sediments and its implications for gas hydrate exploration [J]. Marine Geology & Quaternary Geology,2022,42(1):111-122. DOI: 10.16562/j.cnki.0256-1492.2021040101

海洋沉积物微量元素地球化学特征对天然气水合物勘探的指示意义

Trace elements geochemistry of marine sediments and its implications for gas hydrate exploration

  • 摘要: 天然气水合物与资源和全球环境变化等重大科学问题密切相关。前期关于甲烷渗漏区地球化学特征的研究主要集中于浅表层沉积物(<20 m),而浅层沉积物(>20 m)地球化学特征知之甚少。为探讨海洋浅层沉积物微量元素特征与天然气水合物勘探的相关关系,对南海神狐海域沉积物进行了4个站位的钻探取样,分析了样品主、微量元素和有机碳地球化学特征,并采用氧化还原状态以及Mo与TOC相关关系的分析方法进行探讨。结果显示,沉积物主量元素特征主要受到陆源碎屑物质输入的主导,与天然气水合物富集无明显关系。水合物赋存段及附近沉积物中Ba和Mo元素高度富集,存在明显的“Ba峰”和“Mo峰”,主要是由于天然气水合物分解释放大量甲烷产生的硫化环境所导致。因此,沉积物中的Ba和Mo富集特征可作为识别可能存在天然气水合物分布的重要地球化学指标。

     

    Abstract: Gas hydrate is closely related to some major scientific issues such as energy supply and global environmental changes, and has become one of the hotspots of the world. Previous studies of the geochemical characteristics of methane seepage areas were mainly focused on shallow sediments, while the geochemical characteristics of deep sediments are ignored to certain extent. In order to explore the relationship between gas hydrate and the characteristics of trace elements in deeper sediments, 4 holes have been drilled and sampled at the Shenhu area of the South China Sea. Main, trace elements and organic carbon geochemical characteristics of the samples are analyzed and the oxidation-reduction state and their correlation with Mo and TOC discussed. The results suggest that the major elements in the sediments mainly come from terrigenous clastic material input, without obvious relationship with the process of gas hydrate enrichment. In the area rich in natural gas hydrate, Ba and Mo elements are always highly enriched showing obvious "Ba peaks" and "Mo peaks" owing to the sulfidation environment caused by the decomposition of natural gas hydrates. Therefore, the enrichment of Ba and Mo in the sediments can be used as important geochemical indicators to possible presence of gas hydrate accumulation.

     

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