关键词: 青岛西海岸, 断裂, 古构造应力场, 牟平—即墨断裂带

Abstract:

The southern end of Muping-Jimo fault is located in the western coastal region of Qingdao. Based on detailed field geological investigation, the characteristics of the fault were discovered in the area, and the paleo-stress state and dynamic mechanism were also discussed. The results show that, firstly, the structure of the fault along the western coast of Qingdao mainly consists of large numbers of shear joints, smaller faults and dikes; secondly, the dominant directions of shear joints are mainly four groups, i.e.NW-SE, NE-SW, E-W and S-N trending,and the extending direction of faults is mainly near NE trending; thirdly, the inversion of paleo-stress state reflected that  the study area had undergone two compressional activities since Late Cretaceous, S-N trending compression in the early stage and nearly E-W trending compression in the later stage; fourthly, the compression in the early stage might be associated with NW-SE trending compression occurred in the North China Craton, which derived the local stress field with the SN direction in the Late Yanshan movement, and the E-W trending compression in the later stage might be related to Qinghai-Tibet Plateau extrusion toward the east since Paleogene and the westward extrusion caused by Japan sea expansion  since Miocene; and lastly, Muping-Jimo fault  successively occurred at least two strike slip motions since Late Cretaceous, i.e.sinistral strike slip and dextral strike slip.

Key words: western coastal region of Qingdao, fault, paleo-stress field, Muping-Jimo fault