A METHOD FOR DETERMINING THE HISTORY OF FAULTS USING THE MODEL OF FAULT DISPLACEMENTS

There are extensive information on the nuclei,propagation and linkage of faults recorded by the displacements of faults.By utilizing the model of fault displacements,a method to study the history of faults based on observed data of fault displacement was proposed.Taking the Zhangdong normal fault in the inshore of the Dagang Oil Field as an example,the results showed that the restored fault displacement in different sedimentary stages tended to increase,decrease and then increase less with time.It reached the minimum of displacement during sedimentation of the Oligocene Dongying formation,and representd the relatively quiet epoch in regional extension.The parameter of fault propagation is larger in the Eocene than in the Neogene,the latter ca.1.0.This indicated the tendency of decrease in the fault activity with time,corresponding with the evolution of the basin which experienced intense riftsubsidence in the Eocene to depression in the Neogene.It was during the deposition of the Oligocene Dognying formation that the fault activity had generated both the maximum displacement and the maximum lateral variation in displacement.