Paleogene sediment in Dongpu sag had filled in a complex half-graben controlled by Lanliao fault.Except for an obvious change in its surface and detachment detpth along the axis of Dongpu sag

the Lanliao fault system can be generally described as having a listric surface.The northern segment of the fault system is a relative low-angle listric normal fault with detachment depth of 9-12 km.The middle segment is a relative high-angle listric fault with detachment depth of 14-16 km.The southern segment is a ramp-flat fault with detachment depth of 8 km in the upper part of the fault and of 11-13 km in the lower part of the fault.The kinematics of these segments also vary in different stages at Paleogene

causing the extension of the middle segment and its proportion to the total extension of Dongpu Sag relatively larger than the rest part of the sag.Under the impact of Lanliao fault geometry and its kinematics changes along the axis of Dongpu sag

the depression had developped quite different structural styles

deposit patterns and geological conditions for hydrocarbon accumulation.