Gravity Magnetic And Seismic Interpretation On The Depth To Magnetic Basement Of The South Yellow Sea Of China

The present study shows that there are good prospects for oil and gas in theSouth Yellow Sea region, and the present target for exploring oil and gas is theMesozoic and Paleozoic formation. The formation almost dose not include magneticmaterial in the South Yellow Sea region, just for weaker magnetic; the regionalmagnetic anomaly is caused mainly by Proterozoic and Archean metamorphicbasement. Above all, calculate the depth to magnetic basement is a far-reachingsignificance for determining the thickness of the middle Paleozoic strata, dividingtectonic units, predicting the oil and gas strata and the other deep structures of theSouth Yellow Sea.On the basis of the project of the oil and gas resources survey in the SouthYellow Sea and the collecting and sorting gravity and magnetic data of1:1,000,000scale in the South Yellow Sea region, and the other previous information andresearch results, the paper interprets five profiles which are achieved by2.5D gravitymagnetic seismic Interpretation and calculates the depth to magnetic basement in theSouth Yellow Sea region by the method of Source Parameter Imaging and draws themaps including the depth to magnetic basement map of the South Yellow Sea regionand gravity and magnetic and seismic explanation profiles map and the otherfundamental maps. Meanwhile, the paper divides tectonic units according to gravityand magnetic anomalies field and the depth to magnetic basement and analyzes theburied structural features comprehensively. The main conclusions andunderstandings are obtained as following:Firstly, the southern and northern depth to magnetic basement in the SouthYellow Sea region is shallow, and the middle is deep. The region from south to northin turn can be divided into three parts including Qianliyan uplift depth area tomagnetic basement，northern depression-the central uplift-southern depressiondepth area to magnetic basement, Wunansha uplift depth area to magnetic basement.Secondly, the comprehensive quantitative results were obtained according to theprofile inversion results and the depth to magnetic basement. The depth is relativelystable in Wunansha uplift depth area to magnetic basement, generally in the4-5km.The depth to magnetic basement in the northern depression-the central uplift-southern depression the depth area to magnetic basement is the deepest in the SouthYellow Sea, generally in the8-13km. The depth to magnetic basement in Wunanshauplift area is generally in3-6km.Thirdly, the concealed structural features are analyzed according to the profileinversion results. Cenozoic strata directly covered over the marine strata ofPaleozoic and Mesozoic. The density of magnetic crystalline basement isnonuniform which result in low gravity abnormity is existed in high gravityabnormity in the Qianliyan area;Northern depression is complex and unconformity, and the faults and intrusiverocks are general absence, Neopaleozoic and Triassic strata are generally missing inthis area. Mesozoic strata are generally missing in Southern depression, andNeopaleozoic strata are missing in local areas. The faults in central uplift area aredeveloped which makes strata decline and uplift.Triassic strata are missing in the east of central uplift area, but saved morecomplete in the west of central uplift area.In the Wunansha uplift area, the whole strata are saved, and the large invasiverocks are existing in some areas, and the basal magnetic is unevenly distributed.