Earth Science Frontiers ›› 2023, Vol. 30 ›› Issue (4): 196-208.DOI: 10.13745/j.esf.sf.2022.10.20

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Spatio-temporal relationship between two kinds of deep-water sedimentation on the Ying-Qiong slope, South China Sea

WANG Hairong1,2(), YU Chengqian1,2, FAN Tailiang1,2, CHAI Jingchao3, WANG Hongyu1,2, GAO Hongfang4   

  1. 1. School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China
    2. Key Laboratory of Strategy Evaluation for Shale Gas of Ministry of Land and Resources, China University of Geosciences (Beijing), Beijing 100083, China
    3. The Exploration Enterprise Department of Qinghai Oilfield Company, Dunhuang 736202, China
    4. Guangzhou Marine Geological Survey, Guangzhou 510098, China
  • Received:2022-08-05 Revised:2022-09-06 Online:2023-07-25 Published:2023-07-07


Large amounts of oil and gas are discovered in recent years in the Yingqiong slope deep-water area, northwestern South China Sea, demonstrating the region’s high potential for oil and gas exploration and production. Deep-water sedimentation is often controlled by various mechanisms including gravity flow and contour current. Where and when these mechanisms operate and interact, and to what extent they affect or control sedimentary patterns, can result in different understandings of the regional sedimentary facies distribution due to spatio-temporal variability of hydrodynamic properties. This in turn can complicate the determination of sand body type and distribution and thus hinder gas and oil exploration and development in the region. Based on the seismic facies and stratigraphic superimposed pattern presented by the seismic data, this paper confirms the existence of two types of Miocene sedimentary systems on the Yingqiong slope: gravity (flow) and contour current sedimentary systems. These two systems are adjacent to each other sequentially in time and space, with the former superimposing over the latter in a stepwise pattern prograding towards the slope while the latter exhibiting a retrograde pattern. The boundary between the two systems indicates a special, diachronic “facies transition” interface, and, accordingly, the spatio-temporal relationship between the two distinct sedimentary processes (gravity flow and contour current) is restored. The stepwise progradation-retrogradation relationship between the two sedimentary systems can be attributed to three factors: the abundant supply of clastic materials from a multi-directional Middle-Miocene source system; the resulting strong gravity flow activity; and contour currents induced by deep-water circulation in the South China Sea. The magnitude of gravity flow largely controls the distribution range of the contour current sedimentary system, leading to a spatio-temporal stepwise progradation-retrogradational pattern.

Key words: the South China Sea, Yingqiong slope, deep-water, gravity flow, contour current

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