Study On Pre-Mesozonic Basement Of The North Yellow Sea Basin By Comprehensive Explanation Of The Geologic And Geophysical Information

The north yellow sea basin lies in the middle of the north yellow sea. In the geotectonic division, it belongs to the eastern part of Sino-Korean platform. This basin is a Mz-Cz overlapping basin, which shapes on the jiao-liao uplift.Recent explorations indicate that the Mesozoic layers are good places for hydrocarbon accumulation. It's known that the pre-mesozoic basement controls the Mz and Cz sediment. So, by the research to the pre-mesozonic basement of this area, we can know the distribution of the Mz and Cz sediment and it can provide geological foundations for the hydrocarbon evaluation and exploration of the north yellow sea basin.This research gathered the geological data,petrophysical data,gravity data,magnetic data,seismic data and drill data of the north yellow sea basin and its adjacent areas. Based on the former research and gathered data, this text made a comprehensive research to the pre-mesozonic basement's buried depth of the north yellow sea basin. Its relief and lithologic character and magmatic activity by some comprehensive explanation methods, like geology-geophysics and point (drill)-line (seismic)– area (gravity and magnetism) and forward modeling and inverse modeling. The conclusions as follows:1) The pre-mesozonic basement of the north yellow sea basin is composed of Archean and Proterozoic metamorphic rocks,which belong to Anshan group,Liaohe group,Jiaodong group and Fenzishan group, and Sinian epimetamorphic rocks,lower Palaeozoic carbonate rocks and upper Palaeozoic clastic rocks;2) The pre-mesozonic basement's buried depth of the north yellow sea basin inverted by gravity data fluctuates highly, about 1500m to 5500m. Its fluctuation is similar to the pre-mesozonic basement's top surface explained by seismic data; 3) The magnetic basement inverted by magnetic data is about 1000m to 7500m. As a whole, it has the character: east deep and west flat; north and south flat, and the middle part deep. Its fluctuation is similar to the pre-mesozonic basement's top surface explained by seismic data;4) There are some clear angle disconformities between the pre-mesozonic basement and its overburden sediment present. The surface of equal horizon velocity about 5000m/s can be regarded as the pre-mesozonic basement's top surface, and it's similar to the result explained by seismic data;5) The fracture formations are highly developed in this area. The basal fractures's dominant trend is NE and NW, and it controls the distribution of secondary structures of the north yellow sea basin;6) Although LiaoDong peninsula and ShanDong peninsula's magmatic activities are exquisite, the north yellow sea basin doesn't develop.It's favour of the hydrocarbon's generation and conservation.