南海北部陆坡天然气水合物的沉积物孔隙水地球化学研究进展

孔隙水地球化学异常是天然气水合物勘探的重要工具之一，南海北部陆坡地区拥有良好的天然气水合物成藏潜力，孔隙水地球化学异常在南海的天然气水合物勘探中发挥了重要作用。其中与水合物直接相关的氯离子含量异常被用于识别神狐及东沙海域钻探区的水合物层和计算水合物饱和度。除直接指标外，浅表层沉积物中的硫酸盐含量及其他与早期成岩作用有关的地球化学异常作为间接指标可用于水合物的找矿预测，研究者们通过对硫酸盐还原过程的判别、硫酸盐甲烷接触界面的计算等方面对南海北部陆坡不同海域的沉积物甲烷通量进行了评估，预测出水合物可能的成藏区域。其他如碘含量、氧化还原敏感元素、氯同位素、地球化学模型等新的地球化学指标和计算机手段也被应用于南海北部陆坡区水合物成藏研究并取得了不错的成效。

PORE WATER GEOCHEMISTRY OF THE GAS HYDRATE BEARING ZONE ON NORTHERN SLOPE OF THE SOUTH CHINA SEA

Geochemical anomalies of pore water may serve as important tracers in gas hydrate (GH) exploration. Anomaly in pore water salinity is a direct proxy for GH occurrence and can be further used for calculation of saturation for GH in sediments. Meanwhile, sulfate contents in shallow sediments, as well as other early-diagenesis-related chemical anomalies are widely employed to prospect for GH. In the investigation of the northern slope of the South China Sea, a land of great potential in GH accumulation, geochemical anomalies of pore water have played an important role. Recognition of GH zone, as well as calculation of GH saturation in sediments of the Shenhu and Dongsha areas were performed based on Cl- abundances. identification of reduction process, calculation of sulfate-methane interface are integrated to estimate the methane flux in this region and further delineated areas with high GH potential. Besides, iodine abundance, redox-sensitive elements, Cl isotopes, geochemical modeling also work as promising tools in gas hydrate prospecting.