Relationships Between Cenozoic Extension And Strike-slip Of Raoyang Sag In Jizhong Depression

Raoyang sag in which have various extensional and strike-slip faults of different scales and types is one of the most important oil-forming sags in Jizhong depression.This paper takes geometry,kinematics and dynamics of extensional and strike-slip faults in Raoyang sags as research objects by analyzing the regional geology background,three dimensional seismic data,structural top surface data and logging data.According to the geology background and the characteristics of three dimensional seismic data,the size and the type of extensional and strike-slip faults in Raoyang sags are redefined.The formation and evolutionary process are restored and the distribution of extension faults are figured out by calculating fault throw,extension throw,extension rate and using the method of balanced cross section.Finally,the extensional and strike-slip faulting mechanism is discussed with the combination of structural physical modeling,deep and shallow geological responses,regional dynamics background.The conclusions can be stated as follows: Strike of NNE and NE Maxi,Hejian,Liulu,Wuyi,Gaoyang-Boye faults are the major boundary faults of Raoyang sags.Affected by these faults,many low grade normal faults are developed at the same time.Strike-slip faults in the zone are symbiotic with the extensional faults which appear in the terminal and a limited area of strike-slip tectonic belt,producing many structural styles.In Paleocene to Eocene when the Kongdian Formation was deposited(E1-2k)to Eocene when the Fourth Member of the Shahejie Formation was deposited(E2s4),the intensity of fault activity has the characteristics of strong in the south and weak in the north.Eocene when the Third Member of the Shahejie Formation was deposited(E2s3)is the major period of the development of the boundary normal faults.After Eocene when the Dongying Formation was deposited(E3d),strike sliping is obvious in the whole sag and strike slip effect of the eastern area is stronger than the western.Since the Cenozoic,the whole sag is affected by the extension and strike slip,but the effect of extention or strike slip is different.In E1-2k to Eocene when the Second Member of the Shahejie Formation was deposited(E2s2),Raoyang sag experienced stronger extension than that of strike slip and the action between them is the shifted.In Eocene when the First Member of the Shahejie Formation was deposited(E3s1)to Neogene,strike slip action is stronger than extensional action.Structural physical modeling results show that en-échelon arrangement of faults can also exist in the extensional environment and the stress field in early Paleogene is mainly dominated by the extensional action.The asthenosphere mantle's upwelling results in the Moho uplift,which produced the metamorphic core complex and the formation of eastern edge of Taihang detachment faults.Jizhong-Tangyin rift system and Baxian-Shulu-Handan strike slip structural zone in Jizhong depression are closely related to the extensional and strike slip action of Raoyang sag.The subduction of the Pacific plate,converging between India and Eurasia plate are the major power resources of extension and strike silp.