Oil & Gas Geology ›› 2015, Vol. 36 ›› Issue (1): 51-60.doi: 10.11743/ogg20150107

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Characteristics and origins of structural deformation in the Paleogene in the Western Sag of Liaohe Depression, Bohai Bay Basin

Yu Fusheng1,2, Dong Yuexia3, Tong Hengmao1, Xiong Lianqiao2, Long Xian2   

  1. 1. State Key Lab of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China;
    2. College of Earth Sciences, China University of Petroleum, Beijing 102249, China;
    3. Research Institute of Exploration and Development, PetroChina Jidong Oilfield Company, Tangshan, Hebei 063004, China
  • Received:2014-06-20 Revised:2014-10-20 Online:2015-02-08 Published:2015-02-11

Abstract:

Research on structural evolution and dynamic processes in the Western Sag of Liaohe Depression is significant to not only oil and gas exploration, but also analysis of the evolution of Bohai Bay Basin and Tanlu Fault.According to seismic interpretation, analysis of the relationship between fault system, deposition thickness and the characteristics of fault intensity, it was concluded that the Western Sag of Liaohe Depression underwent two-phase deformation superimposition in the Paleogene.The early Eocene extensional phase including an initial fault depression stage (Es4) and a strong fault depression stage (Es3) resulted in the NE-SW-trending major normal faults and half-graben filled by the fourth and the third member of Shahejie Formation.The later Oligocene strike-slip phase during Dongying Formation caused the right-lateral strike-slip of the pre-existed basement faults and the formation of new normal fault arrays in NEE-SWW orientation.A structure style with transtension subsidence in the south part and transpression erosion in the north part formed during this stages owing to strike-slip displacement.The transition from extensional deformation to strike-slip deformation occurred during Es1-2.Regional field analyses and sand box simulation results show that the Eocene extensional fault system was controlled by back-arc extension stress, which was triggered by subduction roll-back of the oceanic Pacific Plate from the Asian Continent.And the Oligocene strike-slip fault system was controlled by dextral displacement of Tanlu Fault, caused by the collision of Indian-Australian Plate with the Eurasian Plate.

Key words: extensional structure, strike-slip structure, sand-box model, structural deformation, Western Sag of Liaohe Depression, Bohai Bay Basin

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