Geophysical Survey Research To Deep Structure Of Huanggangliangganzhuermiao Metallogenic Belt,Southeast Inner Mongolia

The Huanggangliang-Gangzhuermiao metallogenic metallogenic belt in the southeast of Inner Mongolia is an important polymetallic ore belt in southern Greater Khingan range and Skarn-type Baiyinnuoer Pb-Zn deposits and Shuangjianzishan Pb-Zn-Ag deposits can be found in this region.Currently,since shallow mineral resources are mostly developed,it became more critical to find deep mineral resources,while one of the major issues of deep mineral resource search is the study of deep structure.In this paper,field data of 3 magnetotelluric(MT)profile:L1,Huaganzigou-Wenduoerchagan;L2,Wanfu-Haleyinengele;L3,LaodingjiayingziDamohanshaorong were collected,while two-dimensional Non-Linear Conjugate Gradient(NLCG)inversion was conducted with unified parameter setup,thus two-dimensional electrical structure model of earth's crust in the area covered by the test lines was generated.On the basis of physical property statistical analysis,the gravity data in this study area were processed through upward continuation,with the help of three-dimensional inversion of aeromagnetic data after different depth slices,and the use of Theta maps and Tilt gradient methods for boundary recognition processing,deep structure of HuanggangliangGangzhuermiao metallogenic belt in the southeast of Inner Mongolia was further discussed,and some new understandings were reached:1.The data obtained from physical property tests in the study area show that the Cretaceous and Jurassic strata are of low density and weak magnetic performance,Triassic rocks are of high density and stable magnetic performance,while the Yanshanian intrusive rocks are of weak and unstable magnetic performance.Locations of DalinuoerHonghaoerba fault zone(F1)and Huanggangliang-Gangzhuermiao fault zone(F3)can be effectively identified on Bouguer gravity anomaly and three-dimensional inversion depth maps of aerodynamics.When the volcanic basin and compound rock mass in the study area are extended upward to 10000 m high,the gravity anomaly area still exists,thus it can be inferred that the extension of the rock mass in this area is at least 5-10 km.From the anomalous map of aeromagnetic sections at different depths in the study area,it can be seen that the overall reflection is an elliptical distributed weak magnetic field,corresponding to a large number of acidic,medium-acidic rock masses and it can be estimated accordingly that the depth of the magnetic body can be within about 10 km.Three main fault zones were found in the study area with Theta diagram analysis on Gravity data for boundary recognition analysis and interpretation.With Tilt gradient method,boundary identification of magnetic survey data was conducted and thus the anomalous characteristics of fault structure(lithological contact zone)in the study area were explained.2.From the electrical structure point of view,the regional low-impedance anomaly zone of crust is basically consistent with the known fracture zones.The electrical gradient zone structures of different sections are similar,thus indicates that the inversion model is accurate.Volcanic basin in L2(Wanfu-Haleyinengele),from east to west,appears as massive highresistance strip to low-resistance-inverted trapezoid shape high resistance and low-resistance section at west side.The deep high-resistance layer could be the electrical reflection of basal strata,and the shallow middle-low resistance layer can be the sedimentary cap of Paleozoic,Mesozoic,and Quaternary with thickness of around 1.5km.Meanwhile,the crater of the Taijiaobao volcano in the northwest of the L2 section is electrically reacted as highimpedance anomaly,and the shallow low-resistance is estimated to be generated due to water filling in the fracture zone.The volcanic channel is located at the intersection of Dalinuoerhonghaoerba fault zone(F1)and Baiyinnuoer-Nailinba fault zone(F2).Magma intrusion still remains in its deep part.3.Based on the characteristics of deep electrical structure as well as analysis and interpretation of gravity and magnetic geophysics,it can be inferred that the rock masses of deep part in study area are successively Triassic,Jurassic,and Cretaceous.After the third stage of magmatism,Baiyinnuoer complex rock mass was formed.The dynamic mechanism and ore-controlling effect of the complex rock mass influenced the metallogenic model of the area and guided the ore search in other parts of the area.