Abstract:Objectives: Soft- sediment deformation structures have been identified in Gushan Group of Cambrian of lower Palaeozoic in Bohai Sea area for the first time. Methods: Based on the detailed observation and description of drilling cores, typical sedimentary structures including liquefied diapir structure, liquefied carbonate volcano, liquefied micritevein, liquefied breccias and step microfaults have been observed. Results: There are liquefied diapir structure——liquefied micritevein belt, liquefied breccias zone and step microfaults belt from bottom to top in vertical profile of the both stages according to the brittle and plastic deformation characteristics. Conclusions: The seismites of this formation may be account for the activities of ancient Tanlu fault zone in Cambrian, and is also the response of the splitting of the SinoKorean plate which cracked into North China plate and Jiaoliao plate.