Study on the prospecting model of concealed MVT lead-zinc deposits in northeastern Yunnan Province: A case study of Maozu lead-zinc deposit

Northeast Yunnan Province is one of the most important production areas of MVT lead-zinc deposits in China. In recent years, with the gradual depletion of resources in shallow mining areas, it is urgent to find new replacement resources in the peripheral and deep parts of mining areas. Taking the typical MVT Maozu lead-zinc deposit in Qiaojia county as an example, this paper puts forward a prospecting model suitable for deep exploration of MVT lead-zinc deposits in this area. This prospecting model is based on comprehensive exploration methods tests of known deposits around the mining area and detailed study of the geological background, metallogenic model, deposit characteristics, and prospecting indicators of MVT deposits in this area. The experimental data show that the high-value Pb-Zn-Ag anomalies concentrated along the fault fracture zone in the geochemical survey indicate that there are signatures of ore-forming hydrothermal activity in the deep parts of the faults. The audio frequency magnetotelluric method can be used to identify the burial depth of concealed orebodies, the fluctuations in favorable ore-forming interfaces between the Ediacaran Dengying Formation and the Cambrian Qiongzhusi Formation in the deep underground, and the tendency and scale of the ore-forming faults. The intermediate gradient IP (Induced Polarization Method) measurement of an area can delineate the favorable prospecting area (high polarization anomaly area) on the “horizontal plane scale”, and large-scale IP sounding profiles can further delineate the favorable ore body target areas that are of low resistivity and high polarization anomaly on the “vertical space scale”. The research results show that the combined use of the shallow and deep exploration technologies described in this paper, including the combined element anomalies of shallow geochemical exploration, the deep geological structure of the resistivity profile, and the IP anomaly bodies of the plane and profile, can provide interdisciplinary evidence support for optimizing the deep prospecting target area in this area, and the turning points of anticline and syncline folds close to ore-guiding (controlling) faults and the stratigraphic interface of the Dengying Formation and the Qiongzhusi Formation are preferred drilling verification locations.