Abstract:

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 Es₄ depositional stage,they were joined together and became one fault in the Es₃ 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 Es₄ 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.

Key words: Dongpu depression, Changyuan fault, growing of normal fault, evolution of half-graben