## 2 Geological Overview and Geophysical Model
### Geological and Geophysical Model of the Ore Deposit  
Based on existing geological data and previous research, our research group conducted an in-depth study on the geological model of the Jinding lead-zinc deposit and proposed a two-dimensional geological model of the deposit[], as shown in Figure 2.  
In Figure 2, the shallow surface is a thin layer of soil and sand-gravel rock. Below it is a dome structure and a sliding surface mainly composed of mudstone and argillaceous  
Figure 2: Two-dimensional geological model of the Jinding lead–zinc deposit. silt. Between the sand-gravel rock and the dome structure, there are tabular, layered, and stratoid sandstone-type ore bodies. Below the fault structure are limestone and breccia ore bodies, and below these bodies is limestone. There are deep fractures between the limestone layers. To establish a geophysical model of the deposit, it is necessary to measure the electrical parameters of the geological model. For the resistivity parameters of rock ore, the SQ-3C dual-channel lightweight-induced polarization instrument is used to measure the resistivity and polarization amplitude/frequency of the rock samples using the forced current method. Table 1 shows the electrical properties of the rocks in the Jinding mining area. The resistivity of various rocks in the mining area can be divided into five levels. Limestone has the highest resistivity, above 10,000 \(\Omega\cdot\)m. Pure sandstone comes next, with a resistivity of around 6000 \(\Omega\cdot\)m. Limestone breccia-type sulfide ore has a resistivity of approximately 3000 \(\Omega\cdot\)m. Lead-zinc oxide ore has a resistivity of about 1500 \(\Omega\cdot\)m, and sandstone-type sulfide ore has a resistivity of 400-500 \(\Omega\cdot\)m. The lowest resistivity is found in mudstone, argillaceous siltstone, and fine sandstone, at approximately 200 \(\Omega\cdot\)m. The polarizability of mudstone, argillaceous siltstone, sandstone, and limestone is around 1.0%. Lead-zinc oxide ore has a polarizability of about 3.0%, and limestone breccia-type sulfide lead-zinc ore has a polarizability of about 4.5%. Primary sandstone-type sulfide ore has the highest polarizability, at around 20.0%. The above analysis shows that mudstone, argillaceous siltstone, and fine sandstone have basically the same electrical characteristics, with a resistivity of between 100 and 200 \(\Omega\cdot\)m and a polarizability of less than 1%, indicating low resistivity and low polarizability. However, regardless of whether it is primary sulfide ore or oxidized ore, the resistivity of the ore body is between 400 and 500 \(\Omega\cdot\)m, and the polarizability is approximately 4-20%. As can be seen from the typical exploration profile in Figure 1, mudstone and argillaceous siltstone basically constitute the surrounding rocks of the lead-zinc ore body. Therefore, the lead-zinc ore body in the area should exhibit relatively high resistivity and high polarizability characteristics. When the surrounding rock is locally limestone, it exhibits low resistivity and high polarizability characteristics. Therefore, based on the 2D geological model that uses the electrical parameters of rocks in the Jinding lead-zinc deposit (Table 1), a 3D geophysical model is constructed, as shown in Figure 3. In the figure, the first layer represents the surface covering layer with a thickness of 100 m. Its main component is sand and gravel strata, and it has an average resistivity of 200 \(\Omega\)m. Beneath the covering layer lie domes and concealed deep