Oil & Gas Geology ›› 2018, Vol. 39 ›› Issue (5): 1037-1047.doi: 10.11743/ogg20180517

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Geologic architecture and tectonic evolution of Xushui Sag,Bohai Bay Basin

Shan Shuaiqiang1, Zhang Yuying1, Zhang Ruifeng2   

  1. 1. School of Energy Resources, China University of Geosciences(Beijing), Beijing 100083, China;
    2. Huabei Oilfield Company Ltd., PetroChina, Renqiu, Hebei 062552, China
  • Received:2018-05-15 Revised:2018-07-16 Online:2018-10-28 Published:2018-09-06

Abstract: The Xushui Sag,located in the western Bohai Bay Basin,is separated from the Taihang Mountain uplift by the Taihang Mountain piedmont fault to its west.In order to improve the understanding of the formation of the sag and facilitate petroleum exploration in the region,we systematically studied the geologic architecture of Xushui Sag through the drilling and seismic data.Characteristics of the major faults in the study area were revealed based on fine interpretation of the seismic profiles within the sag.The post-Paleogene tectonic evolution process of Xushui Sag was reconstructed via the balanced cross-section technique.The results show that there are two regional unconformities in the Cenozoic in the Xu-shui Sag,one being at the base of the Paleogene and the other being at the base of the Neogene.According to these two unconformities,three tectonic layers,namely the basement,the Paleogene and the Neogene-Quaternary layers,are subdivided.The structural framework of the study area with faults occurring in its west and north and overlapping occurring in its east and south,is controlled by the NE-trending Taihang Mountain piedmont fault and the NWW-trending Laishui fault.This study demonstrates that the post-Cenozoic tectonic evolution of the study area can be divided into four stages:intense rifting stage,continuous rifting stage,transitional stage from rifting to depression and depression stage.Rifting in the Xushui Sag,characterized by episodic activities,began to grow in the Early Paleocene and proceeded until the Late Oligocene.

Key words: geologic architecture, tectonic layer, tectonic evolution, Taihang Mountain piedmont fault, Jizhong Depression, Bohai Bay Basin

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