东濮凹陷长垣断层的生长特征与半地堑演化

GROWING CHARACTERISTICS OF CHANGYUAN FAULT AND HALF-GRABEN EVOLUTION IN DONGPU DEPRESSION

通过分析长垣断层不同地质时期垂直位移分布特征 ,反演了长垣断层的生长过程 ,发现长垣断层是由南北两个断层段逐渐生长连接形成的 ,不同地质时期长垣断层表现出不同的生长特征。沙四期长垣断层表现为两个独立的断层段 ,沙三期断层段连接起来 ,但各断层段仍表现出独立正断层的位移分布特征 ,即断层段中央附近垂直位移最大 ,向两端逐渐减小 ,断层段分别控制半地堑 ,它们连接处表现出断层位移亏损特征 ,并在其近旁发育横向突起 ,起到分隔半地堑的作用。沙二 -东营期断层段连锁形成统一的断层系统 ,沉降中心向长垣断层中央迁移 ,横向突起沉降 ,长垣断层上盘形成统一的半地堑。

Through analysis of distribution features of vertical displacement in different geological periods,the growing process of Changyuan fault has been inversed,which might be originated from two isolated fault segments.This study shows Changyuan fault has different growing characteristics in different geological periods.It consisted of the two individual normal faults in the Es 4 depositional stage,they were joined together and became one fault in the Es 3 depositional stage.However,each segment still had its own displacement features as independent normal fault,i.e.the largest vertical displacement to be in the central part of the fault segment,and became smaller and smaller to both ends.Both fault segments separately controlled the half-grabens,with displacement deficit on the joining site,where a transverse uplift was formed separating the half-graben.An integrated fault system had been successively formed in the Es 4 to Dongying stage.The depo-center then began to migrate toward the central part of Changyuan fault, the transverse uplift began to subside,and an unified half-graben was then formed on the hanging wall of Changyuan fault.