Abstract:

According to data about the texture of the geological section,stratigraphy,hydrogeology,structural movement and sedimentation,and through restorationof palaeo-tectonics and synthetic analysis,the author suggests that in Pre-Jurassic,there was a great NE trend synclinorium,called the Cangxian-Tianjin syncli-norium,in the central-western part of the present Bohai Bay Basin.It spread along the Tianjin-Cangxian-Guantao zone,including the whole Cangxian Uplift,most ofthe Huanghua Depression and a part of the Jizhong Depression,Linqing Depression and Xingtai-Hengshui Uplift.During the Jura-Cretaceous,the synclinorium was remade and further developed as a result of shearing and compressing.However,from the Eocene,itbegan to break up under the tensil-shear stress and developed into uplifts alter-nated with depressions in the central-western part of the basin.The determination of the synclinorium is significant for the study of geological tectonics and further exploration of oil and gas in the region.