北黄海盆地东部前中生界基底特征

北黄海盆地是中国近海唯一未获得油气突破及勘探程度最低的含油气盆地（朝鲜已在该盆地东部实现了工业性油气突破），朝鲜在东部凹陷的3口钻井证实北黄海盆地东部凹陷主体前中生界基底是下古生界(Pz₁)地层，与上覆以砂泥岩为主的中-新生界地层在地球物理特征上有很大差异，该特征提供了以地球物理资料推断和确定中-新生界盆地基底特征的可靠性。通过重力、磁力及大量多道地震资料解释认为，北黄海盆地前中生界基底最大埋深约5.5 km，凹陷主体部位前中生界基底以下古生界碳酸盐岩为主，其东北角可能存在上古生界碎屑岩基底，而凹陷南部可能是元古界浅变质岩基底。

Pre-Mesozoic Basement Characteristics in the Eastern Depression of the North Yellow Sea Basin

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 (Pz 1 ) 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 km 2 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