The Research Of Lithospheric Conductivity Structure In Luxi Region Of North China And "Stand Value" Statistical Method

Luxi region is located in the eastern part of the North China Plain?Eastern boundary is Tancheng-Lujiang Fault zone,Western boundary is Liaocheng-Lankao Fault zone,northern boundary is Qihe-Guangrao Fault zone,southern boundary is Fengxian-Peixian Fault zone,the whole region is like a circular arc.Luxi region is concerned by many geologists,because of its independence and complexity,but they know little about Geological structure and Physical Characteristics in Luxi region due to backward technology and equipment,there are a little Geological explanation of Gravity-magnetic and Aeromagnetic gravity.in this thesis,a l°xl1 MT observation network from the project“deep Exploration Technology and Experimentation"(Sinoprobe)covering the Luxi region is used,then 2D inversion which used NLCG method create different 3D electronic model and have 2D inversion of different parameter,through the comparison between 2D inversion model and 3D forward model,we choose different 2D inversion mode of Luxi region with tao=3.this study have 5 profile including 3 profile with direction from east to west,2 profile with direction from north to south,and 191 measured magnetotelluric sounding points to explain Lithospheric Conductivity Structure of Luxi region.We will use winglink to export the credible data from "stand point"model and processing data with Curve fitting-replace method when we finished work above.We can import data into software named Surfer and get an improved 2D inversion model to compare with original 2D inversion model in order to validate the effectiveness of Curve fitting-replace method,finally we can get the "stand value"in each layer from "stand point" model.The result of the study shows that Luxi region in the depth of 5-50Km have many discontinuous high resistivity zone which surrounded by medium conductivity,the reason of this phenomenon is that there are so many fault zone in Luxi region.We can learn that the thickness of lithosphere is about 50-70Km in Luxi region according to the bottom interface of lithosphere is equal to the top interface of second continuous low resistivity zone,and the thickness of lithosphere is thinning from east to west,this situation is also happened from south to north except Tancheng-Lujiang Fault zone,Jiyang depression and Linqing depression,this result add new evidence about that the thickness of lithosphere is thinning in North China.