Cenozoic Structural Features And Evolution In The West Of Offshore Area, Liaohe Depression

The western offshore area of Liaohe is located in a transition zone from the land area of the West Depression in Liaohe Basin to the Liaoxi Depression in Liaodongwan Bay area. This paper focuses on structural features and evolution and discusses initially the control to the deposition of structural evolution, basing on a large number of actual data and using the extensional tectonic principle and analytical methods of rift basin. The main results and understanding of:Extensional tectonism in the study area mainly displays complex or multiple half-graben, and strike-slip structure. According to the forming time and developed feature of fault, the faults are divided into five types, including the succession of rift-type, type inheritance Depression period, before the recession Cenozoic fault type, Dongying Depression, the end of the period and phase of the development model. The faults assembled as ladder-shaped, feather, y-shaped, cauda equina symptoms and入- type in the section, and as stepped, echelon, brush-type, branch type and distribution of linear type in the plane.According to the fluctuation of basement, tectonic deformation and distribution characteristic of transfer zone, the study area can be divided into six tectonic units, including the Bijialing drape structure of buried hill, western slope region, Hudong fault terrace, Xianhe-Yueya fault nose structural belt, structural belt and Hainan depression region. It zones of the East and West and North and blocks of South and North. The trap can be divided into structural and stratigraphic trap, and six types, including fault anticline, draping anticline, fault-nose, block, stratigraphic overlap and buried hill trap.By analyzing the structural evolution history, it shows that the study area experienced rift stage and depression stage. The faulted depression stage is divided into rift episodesⅠ,Ⅱ,Ⅲ,Ⅳ. The structural evolution controls the distribution and development of different depositional systems, corresponding with the stratigraphic sequence.