Abstract:

Piston Site 14 is located in the central part of the Xisha Trough, northern slope of the South China Sea, whose geological background, gas source, temperature and pressure are preferential for gas hydrate, and some bottom simulation reflectors (BSRs) have been found. The thickness of sulfate reduction zone is about 25 meters, which indicates that gas hydrate perhaps occurs in the deeper part. A series of geochemical anomalies, including higher salinity from interstitial water, higher hydrocarbon gas concentrations and higher thermoluminescence values from sediments, have been detected at interval of 4-5 meters below sea floor at Site 14. The pore fluids with higher salinity and higher hydrocarbon, which related to gas hydrate, probably migrated into Site 14 along faults.

Key words: gas hydrate, geochemistry, pore fluids, the Xisha Trough