Structure and Evolution of Cenozoic in Dongpu Sag

The structural characteristics in different areas in Dongpu sag are presented. The evolutional process of Dongpu sag is studied with balanced cross section method and divided into rift stage of Paleogene and depression stage since Neogene. Based on the characteristics of fault activity of Paleogene, it is divided into four evaluating phases such as the original rift phase (corresponding to Member-4 of Shahejie formation), the major rift phase (Member-3 of it), the inheriting and developing phase (Member-2 to Member-1) and the rift subducting phase (Dongying formation), of which the Member-3 of Shahejie formation is the period of the most important structural shaping for Dongpu sag, forming the structural framework of blocks in south-north direction and zones in east-west direction.