The Structural Development And Evolution Of Huagou Sub-sag And Lizezhen Sub-sag

Huagou sub-sag and Lizezhen sub-sag are on the west side of Dongying sag,and they can be considered as transition zone between Dongying sag and Huimin sag.The surrounding sub-sag have several special characteristics,such as small area,shallow depth and slow sedimentation.This paper,through the construction interpretation of three-dimensional seismic data,combined with logging data,static characteristics for Huagou sub-sag and Lizezhen sub-sag fault system conducted a meticulous depiction,defined the spreading regularity of fault system.Through the vertical activity analysis and balanced-section technique,this paper studied the evolution of structure formation and clarified the period of evolution in Huagou sub-sag and Lizezhen sub-sag of Cenozoic era.Combining with regional tectonic background,this paper analyzed the separation mechanism,to make sure the feature of separation zone and the formation time,reason,mechanism of Huagou sub-sag and Lizezhen sub-sag.Huagou sub-sag has huagou fault and two secondary fracture zone,Lizezhen sub-sag has linnan fault and three secondary fracture zone.The main faults locate in the north of the sub-sag and have a east-west direction.The faults of Huagou sub-sag and Lizezhen sub-sag mainly have tension tectonic style.In different geological periods,there is obvious differences between the intensity of the faults activities.Faults began to form in Ek^Es₄ depositional period,and the activity rate of faults was the most in Es₃^Es₂ depositional period,and then showed a weakening trend,all the faults movement almost stopped in Ng depositional period.According to the analys is of fault activity,balanced section and plate tectonic background,the Huagou sub-sag and Lizezhen sub-sag depression evolutionary process can be divided into four periods:?1?Ek^Es₄ depositional period,sub-sag controlling faults appeared and the sub-sag began to form;?2?Es₃^Es₂ depositional period,the research area was mainly controlled by trending stretching stress,resulting in strong fracturing;?3?Es₁^Ed depositional period,the fracture of sub-sag became weak;?4?From the Ng depositional period,extension of the basin was reduced,Huagou sub-sag and Lizezhen sub-sag were in the depression stage.The main settlement reason of Huagou sub-sag and Lizezhen sub-sag in Cenozoic era is shallow earth crust tension which was controlled by Asthenosphere effluence.But because of the edge attenuation of main faults,Huagou sub-sag and Lizezhen sub-sag had a small settlement thickness.The separation zone of Huagou sub-sag and Dongying sag are hua 30fault,gaoqing fault and bottom split structure,and the separation zone of Lizezhen sub-sag and Dongying sag are lindong fault,gaoqing fault and Pingfangwang structure.