Constrained Inversion And Intergrated Interpretation Of Magnetotelluric And Sesmic Data

The paper based on Sinoprobe,which is accomplished by the university of Geoscience in the magnetotelluric sounding(MT)data acquisition of the long profile in South China.Advanced algorithms for data processing in the laboratory and gain accurate response for the inversion.Using the nonlinear conjugate gradient algorithm(NLCG),calculating the data of Quanzhou-Shaoyang segment,and add the the priori information to constrain the initial model.and last gain the two-dimensional electronic structure model in high accuracy and strong reliability.According to the result of magnetotelluric impedance tensor decomposition,and combined with regional geological information,gain the result is the underground electrical structure of research area is approximately a two-dimensional structure,in which electrical axis is north-east direction 40 degree.For the same data,if the direction of the section is inconsistent with the spindle of the measuring point,the inversion models are significant different.This is due to algorithm for computing do not match the actual terrain,and make the inversion results are not reliable.Combined with seismic and geological data,add the constraint information into the initial model,through contrast the inversion model before and after adding the constraint information,we could find that below the abnormal size,shape are different in the same area,and constrained inversion played a certain constraint in the boundary of the anomalous body,the depth and the size,the latter inversion model boundaries more clearly.After the processing and inversion,we gain the underground structural model of the studing area within 150KM.According to the model,we find the high impedance body was developed,high conductor was not developed in the electrical structure.And Electrical lateral variation of the upper crust is great,a number of electrical anomaly zone and distortion zone are distributed along the survey line anomaly zone.Contrast with the regional tectonic information,These electrical anomaly zone and distortion zone are consist with the tectonic fault zone.Regional tectonic information show that this section from southeast to northwest across the Shangyu-Zhenghe-Daepo-Haifeng deep fault zone,Shaowu-Heyuan deep faults,Gan River fault zone and other large-scale tectonic belt.According to the electrical model,combined with previous studies,we speculated that the combination zone of the South China plate and the Yangtze plate lacated in the Shaoyang-Hengyang in Hunan Province,the northwestern boundary is Wenjia city-Taojiang-Chenbu fault zone,the southeastern boundary is Youxian-Shuangpai fault zone.In the Wuyi-Yunkai Caledonian island arc fold system,the Widespread presence of huge amount of granite belt match the Large-scale high-impedance block.The Southwestern Fujian depression zone and the Estern Fujian volcanic depression zone are consisitent with the electrical model.Geological data and the electrical model can mutually verify.