The Formation And Evolution Of Lanliao Fault Zone

Lanliao fault zone is a large normal fault in the southern of North China Platform. It start at southwest side of Lankao and arrive at Yucheng by going through Fanxian and Liaocheng..Studing found that Lanliao fault extend northward in LinQing Depression, then disappear gradually in Yucheng, rather than extending to the east by the Yucheng. The fault is about 300km in length and the grneral trend is the NE-NNE. The fault is a boundary of LinQing Depression, Dongpu Depression and Zhongmou Depression. The fault plane is characterized by slow in top and steep in bottom, showing the different structural styles in the section. There are several depocenter and control seven large half graben in Lanliao fault. Half grabens of different segments existed different activities.This paper discusses the structure of three larger accommodation zones and several subaccommodation zones in Lanliao fault.Based on the theory of tectonic analysis and the method of balanced cross section, the geometry and kinematic characters, the tectonic styles and its superimposition relationship, the evolution of Lanliao fault are discussed in detail. By interpreting seismic profile, making balanced cross section and Lanliao fault evolution section, analyzing fault segmentation, made the following conclusions. The fault control the Cenozoic features in Dongpu and Zhongmu depression,and control Lingqing depression in Mesozoic and Cenozoic and the Cenozoic gives priority to fault.Based on the displacement distribution diagram, flat profile features, depocentre, half graben and accommodation zones. The fault divided into three major fault segment and eleven small fault segment.Lanliao fault keep independent between major segment and small fault segments did not connection in ES4. The fault was not connected among the three depression, the small segments had been connected in depression in ES3. The segments of Lanliao fault were linked togeher as a unified system in Es2- Es1.The fault began to atrophy active on the basis of pre-connection in Ed.The evolution of Lanliao fault is variable along strike displacement that Lanliao fault is composed of more than one fault segment and late connect to a unified whole. The new depocenter still appear in the old position. The fault activity remained stronger in the center of each fault segment than that in its linkage areas.The formation and evolution of Lanliao fault were controlled by many Earth dynamic factors,such as, the exterior pate subduction, collision and the interior mantle upwelling, the change of lithosphere structure etc. Finally, the paper discussed the significance of Lanliao fault in the hydrocarbon and earthquake.