Macroscopic distribution characteristics and evolution process of buried hill in the Huanghua depression, Bohai Bay basin

The formation and development of buried hill are controlled by multi-stage tectonic movements. But their structural forms can be identified because they often occur in group and band distribution in different tectonic settings. With an emphasis on the distribution characteristics of buried hill in the Huanghua depression, this paper analyzed the process and features of buried hill evolution using 3D seismic data. The study shows that the buried hill in the Huanghua depression can be divided into three types, buried hill anticline group formed by differential uplift of basement, large fault nose structure formed by tilting of basement fault block and fault nose buried hill structure of basin margin. The buried hill belt in the Qikou sag generally presents a "wheel hub" pattern, and the structure of buried hill in the Cangdong-Yanshan sag shows integrity which is dominated by large anticline structure. The thrusting fault system of basement resulted in the much complicated internal structure of the buried hill and can be divided into trigonometric thrust structure, piggyback thrusting structure and duplex structure. Three large detached extensional tectonic systems control the distribution of the tilted block buried hill, forming buried hill structural group dominated by fault nose structure and horst structure. The buried hill consists of four main stages of evolution in the Huanghua depression: the construction stage of buried hill interior strata from Mesoproterozoic to late Paleozoic, the tectonic development stage of the buried hill interior in the Mesozoic, the stage of buried hill macro stereotype in the Paleogene, and the subsidence stage of buried hill in the Neogene. © 2019, Science Press. All right reserved.