Oil & Gas Geology ›› 2019, Vol. 40 ›› Issue (1): 123-132.doi: 10.11743/ogg20190112

• Petroleum Geology • Previous Articles     Next Articles

Forebulge migration since the Mid-Miocene in the southern South China Sea: evidences from the Beikang Basin

Wang Longzhang1, Yao Yongjian2, Zhang Li2, Zhou Jiangyu1, XuXing2, Xiao Jiaojing1, Shen Ao1, Xu Qiao1   

  1. 1. Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geosciences(Wuhan), Wuhan, Hubei 430074, China;
    2. Guangzhou Marine Geological Survey, Guangzhou, Guangdong 510760, China
  • Received:2018-09-13 Revised:2018-10-08 Online:2019-02-28 Published:2018-12-08

Abstract:

The 2D seismic data were used to discuss the migration of the Beikang forebulge in the southern South China Sea and its impact on trap formation.The strata overlying the Early Miocene Unconformity(EMU),a regional unconformity,could be simply categorized as draping and horizontal layer series in the Nansha sea area.The draping layer series overlie the EMU directly,show parallel seismic reflection characters of continuous thin layers and thicken southeastward,suggesting suspended sediments.While the horizontal layer series were deposited synchronously in structural lows and continuously onlapped and overlay the draping strata formed early.They are mixed thick sedimentary layers of turbidites and suspended sediments featuring discontinuous or weak seismic reflection.Judged by the migration of onlap reflection termination and thickening of the draping strata,the forebulge has migrated southeastward during its uplifting since the Mid-Miocene,indicating a process of intense flexure and equilibrium rebound occurring at the thinned continental crust in the Nansha sea area.The forebulge migration has caused the formation of a host of buried hills,with the draping and horizontal series of strata serving as favorable seals,which in turn will be conducive to the formation of traps.

Key words: forebulge migration, draping layer series, horizontal layer series, buried-hill trap, Late Cenozoic, foreland basin, Beikang Basin

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