【摘要】 辽河西部凹陷位于渤海湾盆地东北部,其古近纪构造演化与成因机制研究不仅对油气勘探具有指导作用,同时对深入分析渤海湾盆地和郯庐断裂带的成因演化也具有启示意义。通过三维地震资料系统解释和编图、同沉积断裂系统与沉积厚度关系分析、断层活动强度统计等方面研究,认为辽河西部凹陷在古近纪经历了早期伸展和晚期走滑两期变形叠加过程。早期伸展变形发生在始新世,包括初始断陷期(Es4)和强烈断陷期(Es3)两个阶段,形成北东向主干断层及东断西超的半地堑世组合,控制北东向沉积中心的展布;晚期走滑变形发生在渐新世东营期,使先存北东走向基底断层发生右旋走滑位移,并诱导盖层形成近东西向新生正断层组合,从而形成南部张扭沉降、北部压扭隆升的构造格局。Es1-2期是从伸展变形向走滑变形发展的过渡时期,构造活动微弱。区域构造应力场分析和沙箱实验证明,始新世北东向伸展断裂系统受太平洋板块俯冲产生的北西-南东向弧后拉张作用控制,而渐新世走滑断裂系统则受郯庐断裂右旋走滑作用控制,动因来源于印度-澳大利亚板块向欧亚板块俯冲作用产生的远程效应。更多还原

【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.更多还原