Abstract:Penglai group is a monocline with normal sequence, but it has strong deformation. Based on the study of structural deformation of cleavage, fold and ductile shear zone in Penglai group of Qixia area in eastern Shandong province, it is regarded that Penglai group has experienced three stages of structural evolution: the early stage is the fold structure under the extensional structural system, the middle stage is the shear deformation of the middle and shallow layers under the shear contraction system, which are the reflection of the different stages of the supra plate extensional structure in the later stage of subduction and exhumation of Sulu orogenic belt. In the late stage, it is controlled by compressive stress with the trend of NE—SE caused by the subduction of the Pacific plate to the Eurasian plate resulted in the formation of buckle fold with an northeast axis. Penglai group is in angular unconformity contact with the underlying crystalline basement, and later is transformed by tectonism. The deep ductile detachment faults do not affect completely along the angular unconformity interface.
