莱州湾凹陷同沉积断层活动性综合评价

Comprehensive evaluation of synsedimentary fault activity in Laizhouwan Sag

同沉积断层是伸展盆地最基本的地质构造形式,控制着凹陷的平面展布、构造形态、沉积充填以及油气赋存。通过对同沉积断层定量评价方法的适用性及优缺点分析,选取古落差法、滑距分析法和活动速率法对莱州湾地区莱北1号断层、莱南1号断层和莱南2号断层三条典型的同沉积主干断层开展定量评价。结果表明,时间上,三条断层活动性均表现为早强晚弱的特点,其中活动最强烈时期为沙河街组三段沉积时期;空间上,莱北1号断层和莱南1号断层活动由中部向两端迁移,莱南2号断层由东部向中部迁移,其中莱北1号断层活动性最强。

Synsedimentary faults are the most basic geological structural form in extensional basins,which control the plane distribution,structural form,sedimentary filling and hydrocarbon occurrence of sags.The quantitative evaluation of synsedimentary faults mainly includes the growth index method and paleo-drop method based on the thickness of the two sides of the fault,the slip distance analysis method and the displacement-length relationship analysis method based on the fault displacement distance,and the fault activity rate based method.There are three types of activity rate method and sliding rate method.In this paper,the three typical synsedimentary trunk faults,Laibei 1,Lainan 1 and Lainan 2 in the Laizhouwan area are comprehensively evaluated by paleo-drop method,slip analysis method and activity rate method,and the activity time of the three faults is found.Both are characterized by early strength and late weakness,and the most intense period of activity was the sedimentary period of the third member of the Shahejie Formation;spatially,the activity of the Laibei 1 and Lainan 1 faults migrated from the middle to the two ends,and the Lainan 2 The fault migrated from the east to the middle,among which Laibei No.1 is the most active.