Characteristics Of Shallow Geological Structure In The Northern Part Of Yangzhou,Jiangsu And 3D Modeling

Geological structure and tectonic activity are the key elements of geological engineering evaluation.Based on lithology,dating data and heavy mineral assemblage,this paper proposed the division and correlation of Quaternary in the northern part of Yangzhou,Jiangsu.Based on the interpretation of shallow seismic data,a three-dimensional geological structure model of the study area is established.The main points of the study include the following points:(1)The Quaternary System in the study area can be divided into Gaoyou-Xinghua district and Tianchang district.The former quaternary system is divided into Wuduizhen group,Xiaoyaozhuang group,Guannan group and Yujian group,and the latter is divided into Dou Chong group,mogang group,Douchong group,Bogang group,Qiju group and Dadun group.(2)Through detailed quaternary stratigraphic correlation analysis,it is considered that the thickness of the Quaternary sediments in the eastern part of the study area is large,and the thickness is more than 270 m.In the western plain area,the strata are all developed,the largest thickness is about 160 m,while the hilly area is lack of Holocene and upper Pleistocene,and the thickness is quite different.(3)According to the wave group characteristics of the shallow artificial seismic section,3 breakpoints and 2 suspected breakpoints(speculative faults)in the quaternary system are explained,but it is difficult to judge the plane distribution and relationship of the faults reasonably because of the lack of density of the lines.(4)The Quaternary thickness and breakpoint distribution of the shallow borehole data,resistivity profile and seismic data have been established to establish the three-dimensional geological modeling of shallow strata in northern Yangzhou area of Jiangsu.It is considered that the Quaternary in the study area is thicker in East than in West of Northern district,and is thicker in West than in East.The northern part of the Shaobo Lake area has a hidden normal fault heading for NNW and NEE orientation.In the south,there is a normal fault heading towards NNW and SWW orientation.The bottom interface fluctuation pattern is characterized by " protruding in the West and depressed in the East".(5)The Wuxi-Suqian fault,located at the bottom of Shabohu lake,is a quaternary synsedimentary fault based on the judgment of Quaternary and Neogene bottom fluctuations revealed by 3D geological structure models.The latest age of activity is about the Middle Pleistocene.The drop of the Neogene bottom interface cut by fault is 700 meters(L4 line)to 900 meters(L3 line).The interval of the Middle Pleistocene strata cut by fault is about 25.5m.The overall trend of fault is NNW direction,and has the characteristics of high angle tilt and tendency change.It is judged as strike slip normal fault.