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Geoscience ›› 2010, Vol. 24 ›› Issue (3): 424-432.

• Water Resource and Environment • Previous Articles     Next Articles

Influence on Gas Hydrates Formation Produced by Volcanic Activity  on Northern South China Sea Slope

LUAN Xi wu1 , ZHANG Liang 1,2 ,YUE Bao jing 1,2   

  1. 1.Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao,Shandong266071,China;2. Graduate University, Chinese Academy of Sciences, Beijing100049,China
  • Online:2010-06-21 Published:2010-08-17

Abstract:

There are volcanoes developed on the northern South China Sea slope. The influence on gas hydrates formation produced by those volcanic activities is the key problem which should be considered first before field exploration conducted. Based on seismic line interpretation and geological thermal model calculation, this paper concluded that the thickness of gas hydrates stability zone would be influenced by magma intrusion. The shallower the magma intrusion depth is, the bigger the influence to the thickness of the gas hydrates stability zone is, but the shorter the thickness of gas hydrates stability zone recover period time is. When volcanic eruption occurred on the seafloor, the gas hydrate stability zone would be destroyed totally at first, however, it would also recovered after a shortest period of time as comparing to the case of magma intrusion. As to the case of magma intrusion depth of 6 km, the total recover time for the gas hydrates stability zone is about 1Ma. There had been volcanic activities during both Dongsha movement and Liuhua movement. Up to now the influences on gas hydrates stability zone produced by those volcanic activities during those two tectonic movements have been disappeared. Finer sediment grain and lower porosity usually developed on slope area are unfavorable factors for the formation of gas hydrates. As the volcanic activity can both enlarge the sediment porosity and accelerate the migration and accumulation of methane in the slope environment, it can help for the formation of gas hydrates on the slope environment. On the other hand, the higher temperature introduced by magma intrusion will help for the formation of gas hydrates by stimulating the activity of methanogens and producing more methane. The volcanic mountain area of northern South China Sea slope is the favorable target area for gas hydrates exploration.

Key words: northern South China Sea slope, volcanic activity;gas hydrates;formation;influence

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