Oil & Gas Geology ›› 2019, Vol. 40 ›› Issue (4): 864-874.doi: 10.11743/ogg20190415

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Late Miocene to Quaternary sequence architecture and unidirectionally-migrating channels in the northeastern continental slope, Pearl River Mouth Basin

Jiang Jing1,2, Zhang Zhongtao3, Li Hao2, Luo Yi1, Tian Hongxun2, Liu Hanyao2   

  1. 1. China Ocean Mineral Resources R & D Association, Beijing 100860, China;
    2. School of Ocean Sciences, China University of Geosciences(Beijing), Beijing 100083, China;
    3. Shenzhen Branch of CNOOC Ltd., Shenzhen, Guangdong 518000, China
  • Received:2018-10-14 Revised:2019-01-16 Online:2019-08-28 Published:2019-06-01

Abstract: Based on the integrated analysis of 3D and 2D seismic, well-logging and paleontological data, two second-order sequences(CS1 and CS2), eight third-order sequences(S1-S8), as well as three main depositional systems(unidirectio-nally-migrating channels in continental slope, shelf margin clinoforms, and shelf-edge deltas) have been recognized in the northeastern shelf edge of the Pearl River Mouth Basin.From outer shelf to lower slope, four types of continental slope channels can be identified:(1) the partly confined outer-shelf unidirectionally migrating composite channels;(2) the broad and shallow outer-shelf to shelf-break erosional composite channels that are unconfined or partly confined;(3) the confined and deeply incised unidirectionally migrating slope channels with vertical and lateral accretion;(4) the U-shaped and unconfined or partly confined vertical accretional composite channels in lower slope.In addition, in view of characteristic variations of sequence boundary, sequence architecture, and depositional system, two types of compositional models of the system tracts have been concluded:(1) the one mainly composed of widespread shelf-margin unidirectio-nally-migrating channels in the Yuehai and Wanshan Formations, which are quite different from the EXXON sequence model;(2) the one that consists dominantly of the Quaternary high-angle shelf margin clinoforms and slope channels.The sequence architecture and depositional evolution in the continental slope in the study area are controlled by a combination of different factors, such as sea level change, tectonism, subsidence rate, and sediment supply.

Key words: unidirectionally-migrating channel, shelf margin clinoform, shelf margin delta, sedimentary system, systems tract, sequence, Pearl River Mouth Basin

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