## 3 Methodology
### Raw Data Processing
#### 3.2.3 Restoration of Au Geochemical Information  
The geochemical map of the Au element, following the adjustment of the research area, is divided into five categories: extremely high anomaly, high anomaly, medium anomaly, low anomaly, and background. A statistical analysis of the distribution frequency of the 109 Au deposits (points) within the research area across different areas and the area percentage of different partitions is presented in Figure 3. As illustrated in Figure 3, (1) 42.6% of the Au deposits (points) are distributed in the Au anomaly area, but they are not closely related to the medium and high anomalies; (2) 95.5% of the Au deposits (points) are distributed in the low-anomaly area and background area, which collectively occupy 81.6% of the total area of the study area. A mere 4.5% of the Au deposits (points) are situated within the medium- and high-Au-element anomaly areas. It is evident that the use of Au element anomaly information alone is insufficient for the effective reduction of the prospecting target area. (3) If the prospecting target area is only studied based on Au element anomalies, nearly 57.4% of the information will be lost. The above conclusion demonstrates that it is challenging to effectively conduct research on optimizing Au prospecting target areas in the study area by solely examining Au and related element anomalies. Consequently, this study has rectified the Au geochemical information. Considering the absence of natural chemical reactions that can decompose elemental Au particles into an ionic state, the Au element in dispersed flow predominantly exists in an extremely uneven metallic state and is present in granular form. Considering the representativeness of field sampling and assay sampling, along with the geographical location (water system location) of the gold deposit, the surface landscape, weathering conditions, and other comprehensive factors, it has not been observed that 57.4% of the Au deposits (points) in the study area lack corresponding Au element anomalies. According to relevant geochemical theories, all metallogenesis involves the enrichment of a series  
Figure 3: Comparison of the percentage of gold deposits in the Beishan Area of Gansu Province and the percentage of area with different levels of abnormality. of related elements. Elements associated with Au metallogenesis, including Ag, As, Sb, Hg, Cu, and Bi, are typically evenly distributed in the water system sediments in ionic states. Consequently, these elements must share a specific relationship with the Au element. The authors utilized samples with anomalous Au values, along with the entire sample set from the region, to develop a stepwise regression simulation model (Auh) for Au and other related elements (Table 1). The numbers in the model represent the weights of each element or variable within the model. The elements listed in Table 1 were selected using the correlation analysis method in statistics. As shown in Table 1, elements such as Bi, Pb, Cu, Zn, Sb, SiO\({}_{2}\), and Y show a positive correlation with Auh, while elements such as Zn, K\({}_{2}\)O, La, and Be exhibit a negative correlation with Auh. The theoretical value of the Au element (Auh) is calculated using the entire sample in the research area to compensate for the loss of information due to sampling representativeness and other accidental factors, thereby increasing the correspondence between Au element anomalies and existing Au deposits (points), and enhancing the potential value of geochemical prospecting information in the quantitative optimization of prospecting target areas within Au-mining regions. Geochemical maps for Au and Auh fitting values were constructed separately, dividing the areas into five regions: extremely high anomaly, high anomaly, medium anomaly, low anomaly, and background. The frequency of occurrence of the 109 Au deposits (points) within the region was determined, as was the percentage of the region's area occupied by each of the different anomaly regions.