Tectonic Evolution of the Yan ③ Fault Zone and Its Trap-controlling Effect on Yancheng Sag,Subei Basin
The Yan ③ fault zone is located in the Yancheng Sag of Subei Basin,and it underwent multiple per-iods of extension-strike-slip tectonic activities in the fault zone or its surrounding areas,controlling the temporal and spatial validity of the traps.In order to elucidate the influence of these tectonic traps on the differential ac-cumulation of oil and gas,it is necessary to clarify the evolution of the Yan ③ fault zones in different periods and understand the controls of the tectonic deformation on the traps.In this study,we used the high-precision 3D seismic data of Yancheng Sag to analyze the geometric morphology and kinematic characteristics of the main faults and surrounding secondary faults.Meanwhile,we use the back-stripping technique to quantitatively re-store the growth of fault segmentation.A paleotectonic map was used to analyze the deformation laws of the tec-tonic belts at each stage,and analyze the tectonic evolution at each stage and their controls.The results show that the Yan ③ fault zone has undergone three major stages of evolutions.(1)During the sedimentation period of Taizhou-Funing Formation(K2t-E1f4),the NW extension controlled the isolated growth of the western Yan ③normal faults,and the two faults in the eastern section connected softly.At this stage,the fault has no clear controls on the depression,and the trap development is very weak.(2)At the end of Funing Period(E1f4)with the short-term compression-torsion occurring rapidly,it resulted in the reactivity of the Yan ③ faults and forming a series of NW trending conjugate shear faults,and a series of traps formed along the salt fault zone.(3)During the Danan-Yancheng period(E2d-Ny),the SN extension was strong to the east and weak to the west,controlling the reactivity of the Yan ③ fault zone in the east,and meanwhile the tectonic activity adjusted the trap.In general,the overall tectonic activity intensity differs from the'high intensity in the early period and weak in the late period,and high intensity in the east and low intensity in the west'.Meanwhile,with the tec-tonic stress field constantly changing,the tectonic amplitude and area of the traps have been gradually decreased,and the structure has been gradually shifted to the SW direction.
Yancheng SagYan ③ fault zonerestoration of paleo-structuretrap-controlling effecttectonic evolution
国家科技期刊平台
NSTL
万方数据
维普
