| Qaidam Basin is the important Mesozoic and Cenozoic sedimentary basin in China.Many rounds of uranium resource potential evaluation have been carried out in the past,and many sandstone type uranium deposits and uranium anomaly zones have been found in the Northern margin of Qaidam Basin.Breakthroughs have been made in the exploration of sandstone uranium deposits with Neogene Shang Ganchaigou Formation as the target layer in the past decade.Basin in Miocene Shang Ganchaigou Formation formed in the basin structural evolution process of stretching stage,stable region on the edge of the basin structure,extensive alluvial fan and braided river sedimentary system and fan delta depositional system,lithology as a gray or gray give priority to the clastic rock construction,has good mud-sand-clay structure,the uranium ore body that occurs in the Shang Ganchaigou Formation of main sand body-grained sandstone.Because the Shang Ganchaigou Formation is often covered by thick overlying strata or the Quaternary in the basin margin,the sand bodies are buried in large depth and small scale,and the deep space distribution characteristics of the Shang Ganchaigou Formation and its sand bodies are unknown,which is not conducive to the further development of uranium exploration.Controlled Source Audio-frequency Magnetotelluric Method compared with magnetotelluric method,its detection depth,moderate depth from dozens of meters to 2 km,the horizontal and vertical resolution is good,strong anti-jamming capability,compared with Seismic Exploration has low cost,high production efficiency,the advantages of wide scope of application,terrain conditions can quickly obtain electrical structures of deep geological body,at the same time,a large scale,small distance for comprehensive research,with depth and section research advantages of dual nature,is an effective method for the research of deep geological structure.Based on the analysis of the geological and regional gravity and magnetic characteristics of the study area,and the statistical analysis of the detection of the electrical characteristics of the target body,the application research of CSAMT method is carried out.The Canyard resistivity and impedance phase formula of the remote electromagnetic field are briefly introduced,and discusses the field measurement method,device and measurement range selection of CSAMT method.Based on the two-dimensional forward modeling model constructed by typical geological sections,the detection effect of different CSAMT measuring point distances is studied.Based on the geological model of uranium prospecting in the north margin of Qaidam,a geophysical model was established,and the feasibility and effect of CSAMT method for exploring the distribution characteristics of Shangganchaigou Formation and its sand body in the study area were studied by using two-dimensional finite element method.Through the static correction method of smoothing filter,the correction effect of measured data is studied.The best 2D inversion parameters in the study area were obtained by comparing different inversion parameters of 2D OCCAM inversion,and several CSAMT profile data were inverted.According to the geological and geophysical characteristics of the studied area is known,borehole data analysis each section and section resistivity characteristics in the study area,the geological inference and interpretation,finally find out the stratum structure,the structure characteristics of the fracture,purpose layer space distribution and sand body distribution,to achieve the research purpose,research achieved good application results. |
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