Study On Development And Evolution Characteristics Of The Strike-slip Structure In Kendong Area

Kendong area is located in the transition region between Jiyang depression and Bozhong depression,which is also neighboring the Bohai part of Tan-Lu Fault Zone in the east and develops obvious strike-slip structure.Based on the latest 3-D seismic data,well and log data and considering the various methods of fault identification and typical characteristics of strikeslip structure,identify and analyze the strike-slip structure to clear its geometric characteristics after the faults interpretation work.Reference for the fault activity analysis,balanced-section restoration and extensional proportion analysis recovery the evolution process of the strike-slip structure in Cenozoic.Though the above work,study how the strike-slip faults control the development and evolution of structure in Kendong area.There are NNE,NE,EW trending faults in Kendong area.The NE,EW trending faults are mainly extensional fault.The NNE trending faults are strike-slip faults which is divided into two types.According to the tectonic deformation features of the strike-slip faults on surface and profiles,the strike-slip type can be divided into strong,medium intensity and weak,three strikeslip types.Among these types,the strong developments continuous principal displacement zone with more secondary faults;the medium intensity developments discontinuous principal displacement zone with less secondary faults;the weak only developments secondary faults which distribute in the form of en-echelon on surface.All of three types development a main steep fault which cut deep stratigraphic and Negative flower structure except the weak.The strong has obvious self-structure difference in space.Besides,the relationship between strikeslip faults and extensional faults can be divided into cutting transformation and inheritance transformation according to the tectonic deformation features.In Kendong area the right-lateral strike-slip shearing of the strike-slip fault activated at Ed deposition period in the Oligocene.And it activated later and stretched weaker compare with the extensional faults in vertical direction.All of the strike-slip faults have different right-lateral strike slip displacement,Kendong fault in east is the largest,the Kendong-2 fault in central area is the least,Kendong-3 fault in the southeast is medium.During the Paleocene to Eocene in the Cenozoic,Kendong area was mainly in uplift-erosion period,there was no evidence of the strike slip faults activated.The later Oligocene the strike slip faults activated intensively which developed continuous principal displacement faults and had cut the pre-existing extensional faults.Subsequently,the principal displacement faults became discontinuous and instead of secondary faults that distributed in the form en-echelon because of the activity intensity the strike slip faults became weak in the Miocene.Therefore,the Cenozoic evolution of the strike slip faults have passed through two evolutionary stages,including strong strike-slip shearing stage(Ed)and weak strike-slip shearing stage(Neogene).The reform of the extensional faults mainly in first stage.The strike slip faults is the main control of the tectonic development and evolution of Kendong area.It influences the formation of the present fault system which has the obvious region-related features through the reform of the extensional faults,and activated intensively at Ed deposition period in the Paleogene that caused the tectonic subsidence from the Oligocene to now which cause the stepladder-like tectonic framework of Kendong area that the height obviously decrease from the southeast to northwest.