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天然气水合物是一种未来新型能源 ,赋存于低温高压环境下的海洋沉积物中 ,但也可形成于大陆永久冻土带中。天然气水合物资源量巨大 ,具有经济和环境上的研究意义。近年来 ,国际上己对天然气水合物的产况、分布和形成机理开展了大量研究 ,但国内这方面的工作还刚刚开展。对中国南海的调查表明该区存在天然气水合物赋存的有利地质条件、温压条件和富含有机质的沉积条件。在南海的许多海区还发现了指示天然气水合物存在的地震标志 (BSR)。介绍了在南海天然气水合物勘查中的地球化学异常标志。这些地球化学异常的产生可能与天然气水合物的形成或分解过程有关。研究内容包括沉积物中气体含量 (主要为甲烷和乙烷 ) ,甲烷的碳同位素 ,孔隙水中阴离子 (Cl- 、SO2 - 4等 )、阳离子 (Ca2 + 、Mg2 + 、Ba2 + 、Sr2 + ,B3+ 和NH+ 4等 )浓度和δ18O ,δD ,δ11B ,及87Sr/ 86 Sr等同位素组成 ,此外还对海底沉积物的热释光特征和紫外、可见、近红外反射光谱特征开展了探索性研究。通过进一步加强理论和实验研究 ,结合地球物理和地球化学资料 ,在不远的将来将会在南海发现和圈定天然气水合物矿藏。
Gas hydrate is a new type of energy source that can be found in marine sediments under the condition of low temperature and high pressure, but also formed in the permafrost zone of the mainland. Gas hydrate resources huge, with economic and environmental research significance. In recent years, a great deal of research has been done on the production, distribution and formation mechanism of natural gas hydrate in the world. However, the work in this field in China has just started. A survey of the South China Sea shows that there are favorable geological conditions, temperature and pressure conditions and organic-rich sedimentary conditions for gas hydrate occurrence in this area. In many areas of the South China Sea, seismic markers (BSRs) indicating the presence of gas hydrates have also been found. The geochemical anomalies in the exploration of gas hydrate in the South China Sea are introduced. The occurrence of these geochemical anomalies may be related to the process of gas hydrate formation or decomposition. The main contents of the study include the gas content in sediments (mainly methane and ethane), the carbon isotopes of methane, the anions in pore water (Cl-, SO2-4, etc.), the cations (Ca2 +, Mg2 +, Ba2 +, Sr2 +, B3 + And NH 4 +), isotopic compositions of δ18O, δD, δ11B and 87Sr / 86 Sr. In addition, the thermoluminescence characteristics of seafloor sediments and the characteristics of UV, visible and NIR reflectance spectroscopy have also been explored. By further strengthening theoretical and experimental research, combined with geophysical and geochemical data, gas hydrate deposits will be discovered and delineated in the South China Sea in the near future.