## 2 Materials and Methods
### SSIP Technology  
The SSIP method is a frequency-domain IP technique that transmits pseudo-random m-sequence signals and measures the potential response to obtain resistivity, relative phase, and frequency dispersion parameters [51]. By emitting spread-spectrum signals and receiving potential measurements, this spectral IP method acquires multiple observation parameters with large data volumes and strong anti-interference capabilities; it enables effective detection of metallic sulfide deposits, discrimination of graphite interference, identification of alteration zones, and enhanced targeting accuracy for deep-seated concealed ones through complex resistivity spectral analysis in combination with other geophysical \begin{table}
\begin{tabular}{l l} \hline \hline \multicolumn{1}{c}{**Current Electrode (A,B) (m)**} & \multicolumn{1}{c}{**Potential Electrode (P,Pn) (m)**} \\ \hline (180,260);(140,300);(100,340);(60,380);(20,420);(\(-\)40,480); & (0,40);(40,80);(80,120);(120,160); \\ (\(-\)80,520);(\(-\)130,570);(\(-\)190,630);(\(-\)260,700);(\(-\)340,780); & (160,200);(200,240);(240,280); \\ (\(-\)440,880);(\(-\)590,1030);(\(-\)790,1230);(\(-\)1040,1480); & (280,320);(320,360);(360,400);(400,440) \\ (\(-\)1340,1780);(\(-\)1640,2080);(\(-\)2040,2480) & (204,280) \\ \hline (580,660);(540,700);(500,740);(460,780);(420,820);(360,880); & (400,440);(440,480);(480,520);(520,560); \\ (320,920);(270,970);(210,1030);(140,1100);(60,1180); & (560,600);(600,640);(640,680);(680,720); \\ (\(-\)40,1280);(\(-\)190,1430);(\(-\)640,1880);(\(-\)940,2180); & (720,760);(760,800);(800,840) \\ (\(-\)1240,2480);(\(-\)1640,2880) & \\ \hline (940,1020);(900,1060);(860,1100);(780,1180);(720,1240); & (760,800);(800,840);(840,880);(880,920); \\ (680,1280);(630,1330);(570,1390);(500,1460);(420,1540); & (920,960);(960,1000);(1000,1040); \\ (320,1640);(280,2240);(170,1790);(\(-\)30,1990);(\(-\)580,2540); & (1040,1080);(1080,1120);(1120,1160); (1160,1200) \\ (\(-\)880,2840);(\(-\)1280,3240) & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Distribution of power supply and measurement points. Figure 2: Schematic diagram of the arrangement of multi-channel observations at large pole distances. methods, demonstrating excellent application results in mineral exploration [52]. It shows promising potential for mid-deep mineral exploration. The SSIP method can effectively identify the co-occurrence characteristics of tungsten (W) and tin (Sn) minerals by analyzing the frequency-dependent responses of complex resistivity and the phase angle. Due to its semiconducting properties, wolframite ((Fe,Mn)WO\({}_{4}\)) exhibits significant polarization in the low-frequency range (0.1 Hz to 10 Hz), with phase angle peaks typically below 1 Hz and longer relaxation times (1 s to 10 s). In contrast, cassiterite (SnO\({}_{2}\)), influenced by surface redox reactions, primarily responds in the mid-frequency range (1 Hz to 100 Hz), displaying shorter relaxation times (0.01 s to 0.1 s). When these minerals coexist, SSIP spectra demonstrate superposition effects: higher tungsten content enhances low-frequency phase angles and shifts the spectrum toward lower frequencies, whereas higher tin content strengthens mid-frequency responses and accelerates high-frequency attenuation. If their proportions are similar, a bimodal or broad-peak feature may emerge. Additionally, high-frequency signals (>100 Hz) are susceptible to interference from other conductive minerals or electrolytes, necessitating Cole-Cole model inversion for accurate mineralogical discrimination.