Study Of The Deep Electrical Structure And Metallogenic Setting Of The Northeast Jiangxi Ore District

The northeast Jiangxi ore district,which located in the concatenation belt between the Yangtze plate and the Cathaysia plate,is one of the most important part of the Qin-hang metallogenic belt.The area is rich in mineral types,and is mainly dominated by Cu,W,Pb,Zn,Ag,Au and other minerals.In recent years,a world-class tungsten deposit has been discovered in Zhuxi area,which makes the reserves of Jiangxi tungsten mine rank first in China.It also changes the distribution pattern of "south tungsten and north copper" in Jiangxi province,and triggers the upsurge of prospecting and geological research in northeast Jiangxi area.For a long time,the genesis,metallogenic mechanism and the source of massive metallogenic materials in the ore concentration area have been the focus of geologists.During the tectonic evolution of large-scale ore concentration area,various structural or material traces are left in the crust.It is of great significance to detect these traces by geophysical means to understand the deep background and dynamic evolution process of ore concentration areas.Magnetotelluric sounding(MT)is one of the important methods to detect the deep structure of the earth due to its advantages of large depth and high resolution.Funded by the geological survey program undertaken by the Chinese Academy of Geological sciences,“Deep geological survey of the Qin-Hang junction belt and Adjacent Areas”(DD20160082)and “Deep geological survey of the middle section of Wuling Mountain-Jiangnan orogenic belt”(DD20190012),two magnetotelluric sections are arranged in the Northeast Jiangxi Province,cross zhuxi mining area and dexing mining area respectively.On the basis of the detailed processing and analysis of the original data,the author believes that the research area is mainly two-dimensional structure,and has carried out two-dimensional resistivity inversion.Through a large number of model,parameter and constraint tests,a relatively reliable electrical structure model has been obtained.Through the comprehensive analysis of the electrical structure model based on the existing geological data,the following understanding is obtained: The high resistivity anomalies found in the upper crust of the two sections are speculated to be the electrical response of the igneous rock and metamorphic rock base in the study area,and the discontinuous distribution of the high resistivity separated by the low resistivity belt can be related to the crustal decoupling caused by the extension of the lithosphere;The metallogenesis in the study area is closely related to the upwelling of deep thermal materials.The low resistivity anomaly in the lower crust is connected with the low resistivity anomaly in the shallow part,which may be the electrical structure of the magma upwelling channel;The electrical structure model supports the view that the metallogenic materials in zhuxi mining area are mainly crust source components,while those in dexing mining Area are mainly mantle source components,and provides constraints from the electrical structure.