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Geochemical Indications of Possible Gas Hydrates in the Northeastern South China Sea
Author(s) -
Zhengquan LU,
Bihao WU,
Youhai ZHU,
Zuji QIANG,
Zaimin WANG,
Fuyuan ZHANG
Publication year - 2006
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.2006.tb00277.x
Subject(s) - clathrate hydrate , methane , geology , sediment , thermoluminescence , natural gas , mineralogy , hydrate , geochemistry , hydrology (agriculture) , geomorphology , chemistry , irradiation , physics , geotechnical engineering , organic chemistry , nuclear physics
Gas hydrate, mainly composed of hydrocarbon gas and water, is considered to be a clean energy in the 21st century. Many indicators such as BSRs (Bottom‐Simulating Reflections), which are thought to be related to gas hydrate, are found in the South China Sea (SCS) in recent years. The northeastern part of the SCS is taken as one of the most potentials in the area by many scientists. It is situated in the conjunction of the northern divergent continental margin and the eastern convergent island margin, whose geological settings are much preferable for gas hydrate to occur. Through this study, brightness temperature anomalies recorded by satellite‐based thermal infrared remotely sensed images before or within the imminent earthquake, the high content of hydrocarbon gas acid‐degassed from subsurface sediment and the high radioactive thermoluminescence value of subsurface sediment were found in the region. Sometimes brightness temperature anomalies alone exist in the surrounding of the Dongsha Islands. The highest content of hydrocarbon gas amounts to 393 μL methane per kilogram sediment and the highest radioactive thermoluminescence value is 31752 unit; their geometric averages are 60,5 μL/kg and 2688.9 unit respectively. What is more inspiring is that there are three sites where the methane contents are up to 243, 268 and 359 μL/kg and their radioactive thermoluminescence values are 8430, 9537 and 20826 unit respectively. These three locations are just in the vicinity of one of the highest confident BSRs identified by predecessors. Meanwhile, the anomalies are generally coincident with other results such as headspace gas anomaly in the sediment and chloride anomaly in the interstitial water in the site 1146 of Leg 184. The above‐mentioned anomalies are most possibly to indicate the occurrence of gas hydrate in the northeastern SCS.