## 4 Results and Discussion
### Association Rules among Multiple Elements
#### 4.2.3 Controls of Geological Features  
Due to the influence of multiple stages of tectonic and magmatic activities, the fault structures in the study area are relatively well developed. We calculated the Euclidean distance field for the faults in the study area (Figure 14). Then, the 15 mined association rules were overlaid with the fault distance field (Figure 15). We found that more than 86% of the mined rule points are located within 1000 m distance of the fault, especially {Cu (HH)} \(\Rightarrow\) {Co (HH)} (Figure 16) and {Zn (HH), Sb (HH)} \(\Rightarrow\) {Cd (HH)} (Figure 17). The rule {Cu (HH)} \(\Rightarrow\) {Co (HH)} is most predominant near the faults in the northwest and southeast parts of the study area, and three known copper ore occurrences are also near the faults. The rule {Zn (HH), Sb (HH)} \(\Rightarrow\) {Cd (HH)} is most strongly associated with the faults in the southeastern part of the study area, and a known lead-zinc ore occurrence is near the faults. That is, the fault structure has an obvious control effect on clustering of the elements. Figures 16 and 17 show that three copper ore occurrences and one lead-zinc ore occurrence all appear in areas with high densities of their corresponding association rule points. In addition, we extracted streams and catchment areas to analyze whether element co-occurrence is related to stream transport. As shown in Figures 18 and 19, most {Cu (HH)} \(\Rightarrow\) {Co (HH)} and {Zn (HH), Sb (HH)} \(\Rightarrow\) {Cd (HH)} events are distributed in the upper reaches of the streams and catchment areas, so the impact of stream transport on element association rule mining is weak in the study area. Figure 13: (**a**) Association rule mining result, {As (HH)} \(\Rightarrow\) {Sb (HH)}, and (**b**) bivariate spatial cross-correlation indicator, \(I_{\text{AsSb}}\), of As and Sb. Figure 14: Euclidean distance field of faults. Figure 15: Number of mined rule points that are close to faults. The mineralogical composition of lithological strata impacts the coexistence of elements. We overlaid the mined association rules with the geological map and counted the points and density of each rule in the main lithostrata (Figure 20). A greater density and number of points of association rules of sulfides and the related elements occurs in the Proterozoic Baishahe Formation (Pt\({}_{1}\)b) and the Early Permian granodiorite (P\({}_{1}\)\(\gamma\)8), especially  
Figure 19: Rule [Zn (HH), Sb (HH)] \(\Rightarrow\) [Cd (HH)] points overlayed with streams and catchment areas. Figure 17: Rule [Zn (HH), Sb (HH)] \(\Rightarrow\) [Cd (HH)] points within 500 m and 1000 m of faults. (As (HH)) \(\Rightarrow\) (Sb (HH)). The Proterozoic Baishahe Formation (Pt\({}_{\text{t}}\)b) is the basement rock series in the study area, which is divided into carbonate rock, schist, and gneiss. Due to the influence of multiple orogenic events and frequent magmatic activity, the Proterozoic Baishahe Formation (Pt\({}_{\text{t}}\)b) and various intrusive rocks show good metallogenic conditions and prospects in the study area. The Late Triassic Elashan Formation (T\({}_{\text{3}}\)e) is divided into andesite, dacite, and rhyolite. During this geological period, tectonic movements, volcanic eruptions, and structural fractures were developed, which were good storage places for later metallogenic materials. However, because the Late Triassic Elashan Formation is not the main source of metallogenic materials, we found that it is not strongly related to association rules. Figure 21 shows that rule [As (HH)] \(\Rightarrow\) [Sb (HH)] occurs not only in Pt\({}_{\text{t}}\)b but also in the contact zones between intrusive rocks of different ages and Pt\({}_{\text{t}}\)b. According to the geological survey data, the enrichment of Cu, Pb, Zn, Ag, Bi, and other elements in the Proterozoic Baishahe Formation (Pt\({}_{\text{t}}\)b) provides the main ore-forming materials in the study area.