Study On Three-dimensional Electrical Structure Of Dongmen Copper Polymetallic Deposit In Jiangxi Province

The Dongmen survey area of Xinyu City,Jiangxi Province is located in the PingxiangDexing polymetallic metallogenic belt and tectonically in the west part of Pingxiang-Leping depression belt of Qinhang combination belt.The study area is located at the intersection of several polymetallic and nonmetallic metallogenic belts in the metallogenic regionalization,which has very favorable metallogenic conditions and great prospecting potential.Granodiorite porphyry is the main ore-forming rock mass in the area,but there is still insufficient understanding of its upthrust direction,morphological distribution,scale and alteration range.Therefore,this paper uses the multi-array audio magnetotellurism data collected from Dongmen census area to construct the three-dimensional electrical structure model of the census area through data processing and inversion calculation,and discusses the relationship between the electrical structure and metallogenic porphyry and the corresponding strata and structures,so as to provide electrical constraints for the mapping of favorable metallogenic targets in the study area.In order to perform 3D inversion of multi-array audio magnetotelluric data,a multiscale 3D inversion scheme is proposed in this paper.After the feasibility and effectiveness of the scheme are verified by theoretical data inversion,the scheme is applied to the multiscale 3D inversion of measured data in Dongmen survey area.The electrical structure model of the study area shows that the surface is mainly covered by the high resistivity area,but there is a large area of low resistivity in the western shallow layer and extends to the deep northwest and the shallow east direction.Combined with geological,geophysical and chemical exploration anomalies and borehole data,the Huanglong Formation carbonate strata in Dongmen area are mainly distributed in the west of the working area,showing the characteristics of thin in the east and thick in the west on the whole.Zishan Formation strata are widely distributed in the middle and south of the working area,and the distribution range gradually expands with the increase of depth,and the thickness can be up to 1000 meters.The rock mass has a certain scale of underground concealment,magma from west to east along the Yellow Long Formation carbonate rocks and Zishan Formation argillaceous sandstone up-invasion in a large dip Angle.It is concluded that the deep fault structure in the direction of near south north and east west provides a unified channel for magma up-invasion,and the intersection of different strike faults provides more favorable conditions for mineralization.