## 4 Results and Discussion
### Three-Dimensional Metalogenic Prediction  
#### 4.3.1 Three-Dimensional Exploration Criteria  
Based on the concept of a mineral system, this study examines the critical processes related to the Yanshan iron ore deposit--transport, traps, and deposition in terms of rock, faults, and hydrothermal alteration [82; 83]. The expressions of each of these processes in relevant geoscience spatial data are deemed mappable criteria for exploration targeting. The objective of this analysis is to identify geological ore-controlling factors closely associated with mineralization, establish an exploration model, and provide a theoretical foundation for the exploration of highly mineralized areas within the mining region using multi-source and multi-dimensional data [84]. The metallogenic elements of Yanshan Iron ore are shown in Table 6.  
The folds and faults are predominantly developed within the metamorphic rock series and are well defined, significantly influencing the localization of ore deposits, particularly at fold hinges and fault intersections. The closely developed folds and fault structures serve as critical external factors in the hydrothermal alteration of low-grade ore bodies, facilitating migration pathways for hydrothermal activity and creating spaces for the enrichment of ore-forming components [42]. Among these factors, fault structures demonstrate the most significant ore-controlling effects. The intersections of various fault sets, along with faults that transect low-grade ore bodies, facilitate the transport of hydrothermal fluids, induce alterations in the ores, and activate iron through these fluids, ultimately contributing to \begin{table}
\begin{tabular}{c c} \hline \hline
**Expression of Critical Processes** & **GIS-Based Targeting Criteria** \\ \hline The magnetic anomaly of the ore body is & \\ higher than that of the surrounding rock, and & \\ the magnetic anomaly significantly indicates & \\ the presence of rich ore. & \\ \hline The fold structures provide migration & \\ pathways for hydrothermal activity, facilitating & Proximity to Sijiaying compound syncline; \\ the formation of rich ore deposits. & proximity to mignatization \\ \hline Hydrothermal alteration is pronounced in & Proximity to chloritization and carbonatization \\ areas near rich ore bodies. & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Exploration targets of the Yanshan iron deposit. Figure 17: Three-dimensional magnetite intelligent detection results. the formation of rich iron deposits. Consequently, the fault structures, folds, and other geological features in this area establish favorable conditions for the development of high-grade iron ore deposits [46]. Research indicates that migmatization and hydrothermal alteration are key factors in the enrichment of the Yanshan iron deposit. The crystalline basement in the mining area has undergone a high degree of metamorphism, transitioning from granulite-facies to greenschist-facies metamorphism, accompanied by intense and widespread migmatization. Large areas of greissic magmatic are present at the top of the ore body. Simultaneously, strong hydrothermal alteration is observed around the ore body, with common alteration types including chloritization, carbonatization, biotitization, and muscovitization. The widespread development of interlayer faults and fracture zones further facilitates hydrothermal activity. Therefore, the intersections of migmatization, hydrothermal alteration, and fault structures represent critical zones for the concentration of iron-rich ore bodies [85]. In addition to the aforementioned geological factors, the primary iron mineral in this region is magnetite, which possesses a high magnetization rate and exhibits a distinct magnetic contrast with the surrounding rocks, including metamorphic rocks, migmatites, engisses, diorites, and basalts. The magnetic anomalies associated with magnetite are important indicators for mineral exploration in this area.