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.