Geophysical field characteristics and deep ore prospecting prediction of the Nannihu molybdenum lead-zinc-silver polymetallic ore field in East Qinling Mountain

The Nannihu molybdenum polymetallic orefield is an important production area of Mo (W) Pb, Zn, Ag polymetallic ore resources in China, which includes 3 proven super large molybdenum (tungsten) deposit, 3 large molybdenum (tungsten) deposits, and more than 10 medium and large Pb Zn Ag (Au) deposits. The orefield has superior geological metallogenic conditions and deep prospecting potential. The depth of the existing mineral exploration is mainly 500m to a shallow range, and the deep (500-2000 m) prospecting work is basically blank. It is necessary to use the integrated geophysical method to study the metallogenic regularity and predict the new mineral resources. By studying the geological and geophysical characteristics of the area and the geophysical anomalies of the typical deposits, significant research results have been obtained:(1) The intrusion model of the concealed rock mass is established, which is closely related to the mineralization. The whole concealed rocks are divided into three zones from south to north; the depth of the top of the buried rock is 0～800 m, and the distribution area is about 125 km²; the depth of the top of the buried rock is 0.8-1.5 km, and its distribution area is about 158 km²; the depth of the top surface of the buried rock is 1.5-3 km, and its distribution area is about 233 km². (2) The three-dimensional metallogenic model, which is divided into four spatial metallogenic regions from the surface according to the different spatial locations of mineralization, and integrated geophysical prospecting model (the geophysical field marks of the concealed rock mass, the upper zone of the concealed rock mass, the kupola and the porphyry, the ore bodies and the mineralized bodies) are established. (3) It is pointed out that the concealed rock top belt and the kupola above it, dikes, apophyse and porphyry are favorable sites of mineralization. (4) Ore prospecting potential is predicted; the methods for prospecting of tungsten and molybdenum lead-zinc-silver gold mineral deposits are summarized. The research results have important significance for deep prospecting in this area and similar mining areas.