Marine Geology

Seabed pockmark formation associated with mud diapir development and fluid activities in the Yinggehai Basin of the South China Sea

  • DI Peng-fei ,
  • HUANG Hua-gu ,
  • HUANG Bao-jia ,
  • HE Jia-xiong ,
  • CHEN Duo-fu
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  • 1.Key Laboratory of Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301 China; 2.Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, China 510640; 3. China National Offshore Oil Corporation Ltd., Zhanjiang 524057, China

Received date: 2011-08-30

  Revised date: 2012-01-10

  Online published: 2013-02-06

Abstract

Pockmarks, as a sign of gas and fluid seepage on the seafloor, are widely distributed around the center depression and Yingdong Slope area of the Yinggehai Basin. The area of a single pockmark may range from 24×26 to 5×8 m2, its depth may be between 0.5 and 6.7 m, and its shape is approximately circular or elliptical, with a few of them being long strips. The largest one is 300×580 m2, and its depth is 117 m. The pockmark formation correlates with the multiple-stage activity of mud diapirs and the upward migration and eruption of free gases and fluids from the gas reservoir. The pockmarks are usually accompanied with the formation of mud volcano. Paleo-pockmarks (the buried pockmarks) have been discovered along seismic profiles, which indicates that the free gas and the fluid eruption took place in a historical period. The two times of pockmark activity in an identical seepage channel show that the upward intrusion of mud diapir took place intermittently. According to the depth of pockmarks, it is estimated that a 16- to 94-m-thick free gas layer upward venting in the deep gas reservoir is needed to form a 0.5- to 6.7-m-deep pockmark in the Yinggehai Basin.

Cite this article

DI Peng-fei , HUANG Hua-gu , HUANG Bao-jia , HE Jia-xiong , CHEN Duo-fu . Seabed pockmark formation associated with mud diapir development and fluid activities in the Yinggehai Basin of the South China Sea[J]. Journal of Tropical Oceanography, 2012 , 31(5) : 26 -36 . DOI: 10.11978/j.issn.1009-5470.2012.05.005

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