冀中坳陷束鹿凹陷横向调节带成因分析

Origin of the transverse accommodation zone of the Shulu subbasin in the Jizhong depression

束鹿凹陷是冀中坳陷西南部的一个典型的伸展单断凹陷,构造格局简单,存在北东向伸展断裂系统和北西向横向调节带。通过凹陷演化史以及钻井资料分析,探讨横向调节带形成机制和形成时期,提出Ⅰ级调节带形成于凹陷强烈伸展期,Ⅱ级调节带形成于凹陷弱伸展时期。研究认为,边界断裂不均匀伸展和基底古隆起控制Ⅰ级横向调节带的形成,岩性组合差异是Ⅱ级横向调节带形成的引发机制,控洼断层的侧列状交替发育是构造Ⅱ级横向调节带形成的动力机制。

The Shulu subbasin lying in the southwestern part of the Jizhong depression is a typical singledownfaulted subbasin in an extensional system. Its structure is simple with a NE extensional fault system and a NW-trending transverse accommodation zone. Based on the evolutionary history and drilling well data of the subbasin, this paper discusses the mechanism and time of formation of this transverse accommodation zone and proposes that the first-order accommodation zone formed in a stage of strong extension of the subbasin, while the second-order accommodation zone formed in a stage of weak extension of the subbasin. The formation of the first-order transverse accommodation zone is controlled by inhomogeneous extension of the boundary fault and basement uplift, the deference in lithologic association is the trigger mechanism of the second-order transverse accommodation zone, and the alternating development of en-echelon faults that control the subbasin is the dynamic mechanism of formation of the second-order transverse accommodation zone.