Abstract:

The North Yellow Sea Basin is the only one offshore petroliferous basin of China that is very lowly explored and where we have not made breakthroughs in oil and gas. However, Korea has discovered commercial hydrocarbon in the east of the basin.Three boreholes of Korea in the eastern depression give evidences that lower Paleozoic strata (Pz₁) act as the pre-Mesozoic basement of the main body of the eastern depression and differ greatly in geophysical properties from the overlying Mesozoic-Cenozoic strata dominated by sandstone and mudstone. These geophysical data can be reliably used to infer and determine the characteristics of the Mesozoic-Cenozoic basin basement. Based upon the interpretations of gravitational, magnetic and multichannel seismic data, there is an evidence that the maximum buried depth of the pre-Mesozoic basement is about 5.5 km in the North Yellow Sea Basin. If taking the previous buried depth of 1 km as the boundary of the basement, the eastern depression has an area of about 1,700 km².Pre-Mesozoic basement of the depression mainly consists of carbonate rock of Lower Paleozoic, in the northeast corner of the depression may exist Late Paleozoic basement made up of clastic rock, and there may be Proterozoic basement of epimetamorphic rock in the south of the depression.

Key words:  pre-Mesozoic basement, geophysical property, east of the North Yellow Sea Basin