A Study On The Gravity Field And Tectonic Characteristics Of Huanghua Area

The Huanghua area is located in the eastern part of North China,between 116°?120°E and36.4°?39.7°N,have a total area of 8.93×10~4 km~2.Exploration practice and previous research results have proved that the Huanghua area is complex in structure and rich in mineral resources such as oil and gas,which is one of the key research areas of geological structure and hydrocarbon exploration in North China.Although it has undergone more than 50 years of exploration and research,The geophysical and geological work of the whole area is in different levels,which is research degree is higher in depression part and little lower in the uplifts,the application of comprehensive geophysical data to study of the structural system and stratigraphic distribution characteristics of the entire area is limited.Therefore,in order to comprehensively study the structural characteristics of the entire Huanghua area,this article combines the related research results of the predecessors and conducts a comprehensive study on the fault system,stratigraphic development characteristics,basement depth,structural units,etc.in the Huanghua area based on the gravity data.The research results can provide geophysical basis for the structural research of Huanghua area.This paper uses the gravity data in Huanghua area to process the gravity data through analytical continuation,moving average,regularized filtering,trend analysis,vertical second derivative,oblique derivative,NVDRTHDR,etc.Combining drilling,seismic and regional geological research results,the characteristics and causes of gravity anomalies in the area were systematically analyzed,fault structures in the study area were inferred,stratum distribution characteristics were discussed,basement depths were inverted,and structural units were divided.The paper has achieved the following results and conclusions:(1)The high residual gravity anomaly of the Cangxian Uplift and Chengning Uplift in the study area is caused by the basement uplift,while the low residual gravity anomaly within the above-mentioned uplift is caused by the local thickening of the overlying Mesozoic and Cenozoic strata.The low residual gravity anomaly in the depression area is caused by the thickening of the Paleogene strata,and the high local gravity in the depression is caused by the relative uplift of the basement in the depression area under the background of the relatively large basement depth.(2)As the study area has been reformed by multiple tectonic movements,the structural deformation is relatively strong.The faults are densely distributed and complex in shape.Three groups of faults,NE(NNE),NW and near EW trending are mainly developed in the study area.These faults control the stratum distribution in the study area and form the boundary of the secondary structural unit in the study area.(3)The calculation results of the quantitative fitting of the profile and basement depth inversion show that in the Cangxian Uplift and Chengning Uplift,the Mesozoic is missing in a large area,and the thickness of Cenozoic is relatively thin.The average basement depth of the two uplift areas is 3106m and 2607m;in the depression area,the thickness of the sedimentary layer above the basement is relatively large.Although there are also local stratum defects(such as the Cretaceous),the stratum is relatively complete.The average basement depth of all depressions is greater than 3500m.