Structural Characteristics Of Marine Mesozoic And Paleozoic And Prediction Of Distribution Of Their Main Assemblage In The Northern Jiangsu Area

In northern Jiangsu area,the marine Mesozoic and Paleozoic have experienced the transformation and superposition of the tectonic movement.The complex structure and the unsatisfactory formation of the strata and the main assemblage,which is the main reason for the oil and gas exploration evalu-ation.Based on the foreland deformation theory and the results of the large-scale interpretation of the seismic data,the paper analyzes the tectonic deformation characteristics of the marine Mesozoic and Paleozoic in the northern Jiangsu,and establishes the tectonic style,predicts distribution of the main assemblage.The research results are of great significance to the evaluation of oil and gas exploration in the marine Mesozoic and Paleozoic.Based on field outcrops,drilling dataandthe interpretation of local seismic data,this paper analyzes the tectonic deformation of the marine Mesozoic and Paleozoic in northern Jiangsu area,and points out that the marine Mesozoic and Paleozoic in the northern Jiangsu is the north wing of a complex fold.Based on the theory of land front deformation,it divides the root belt,middle belt and front belt from NW to SE.Based on the regional large-scale tectonic framework,the tectonic style of the foreland deformation structural zoning is established by using the theory of foreland deformation.From the root belt to the front belt,the structure stylefrom the imbricate thrust structure type,nappe structure type gradually transition to the broad and gentle fold type,the degree of deformation gradually reduced.The Upper Paleozoic remains more and more in the root belt from west to east.The thrusts in each nappe are gradually slowing from north to south,and the marine strata are getting better from west to east.From west to east fold gradually from the closed into the width in the front belt.Under the guidance of zonal structure,combined with the drilling data,the geophysical interpretation of the local area was carried out for the main assemblage.Based on the results of drilling and seismic interpretation,the distribution range of three sets of main assemblage is predicted with the large section as the constraint.It is believed that the Triassic Qinglong Formation and the Permian are stalked in the coastal area,Sheyang,Yancheng East,Jianhu,Jiangdu-Dongtai,Huangqiao-Hai'an area.Devonian-Silurian in the root belt remaining in Hongze,coastal area,in the middle belt and the front band is more widely distributed and the thickness of stability.Cambrian-Dengying Group,the overall preservation of a better distribution is more stable,only in the northwest of the root belt missing.Based on the distribution characteristics of main assemblages and the structural strength,seismic data quality and trap conditions,the Taixing-Hai'an in the front belt and the Jiangdu-Dongtai in the middle belt are considered as the most favorite exploration plays.