## 3 Data Introduction
### The 1:200,000 Scale Data Source and Analytical Methods  
The 1:200,000 scale geochemical data for the region comes from the regional exploration scanning plan, with the sample medium being river system sediments. The sampling density was one sampling point per 4 km\({}^{2}\), and a total of 39 elements were analyzed (Bi, Cu, P, La, Li, Ag, Sn, Au, Mo, Th, U, W, Sb, Hg, Mn, Cr, Sr, Nb, Pb, Ni, Ti, Y, Cd, Co, Ba, Be, V, Zn, B, As, Zr, F, Fe\({}_{2}\)O\({}_{3}\), K\({}_{2}\)O, CaO, MgO, Na\({}_{2}\)O, Al\({}_{2}\)O\({}_{3}\), and SiO\({}_{2}\)). The study area is located in the right part of the L5033 (Maodeng) 1:200,000 map sheet, and a total of 620 geochemical data points were collected in the study area (Figure 3a). The analysis methods and detection limits for each element are shown in Table 2.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Element** & **Unit** & **Detection Limit** & **Analysis Method** \\ \hline Pb & \(\upmu\)g/g & 0.5 & ES \\ Mo & \(\upmu\)g/g & 0.2 & ES \\ Sn & \(\upmu\)g/g & 0.2 & ES \\ Cu & \(\upmu\)g/g & 0.5 & ES \\ Ag & \(\upmu\)g/g & 0.02 & ES \\ Zn & \(\upmu\)g/g & 11.2 & ES \\ Ni & \(\upmu\)g/g & 0.8 & ES \\ Co & \(\upmu\)g/g & 0.8 & ES \\ As & \(\upmu\)g/g & 0.2 & AFS \\ Sb & \(\upmu\)g/g & 0.05 & AFS \\ Bi & \(\upmu\)g/g & 0.05 & AFS \\ W & \(\upmu\)g/g & 0.25 & POL \\ \hline \end{tabular} Note: ES: electrode spectroscopy; AFS: atomic fluorescence spectroscopy; FOL: polarography; ES: ion-selective electrode method; GF-AAS: graphite furnace-atomic absorption spectroscopy; COL/LCF: colomerty or laser catalytic fluorescence.  
\end{table}
Table 1: The elements, analytical methods, and detection limits of the 1:50,000 scale data.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Element** & **Unit** & **Detection Limit** & **Analysis Method** & **Element** & **Unit** & **Detection Limit** & **Analysis Method** \\ \hline Ag & \(\upmu\)g/g & 0.02 & AAS/AES & Pb & \(\upmu\)g/g & 2 & XRF \\ As & \(\upmu\)g/g & 1 & AFS & Sb & \(\upmu\)g/g & 0.1 & AFS \\ Au & \(\upmu\)g/g & 0.0003 & AAS/GF-AAS & Sn & \(\upmu\)g/g & 1 & AES \\ B & \(\upmu\)g/g & 5 & AES & Sr & \(\upmu\)g/g & 5 & XRF \\ Ba & \(\upmu\)g/g & 50 & XRF & Th & \(\upmu\)g/g & 4 & XRF \\ Be & \(\upmu\)g/g & 0.5 & AES & Ti & \(\upmu\)g/g & 100 & XRF \\ Bi & \(\upmu\)g/g & 0.1 & AFS & U & \(\upmu\)g/g & 0.5 & COL/LCF \\ Cd & \(\upmu\)g/g & 0.05 & AAS & & & \\ Co & \(\upmu\)g/g & 1 & XRF & V & \(\upmu\)g/g & 20 & XRF \\ Cr & \(\upmu\)g/g & 15 & XRF & W & \(\upmu\)g/g & 0.5 & POL \\ Cu & \(\upmu\)g/g & 1 & XRF & Y & \(\upmu\)g/g & 5 & XRF \\ F & \(\upmu\)g/g & 100 & ISE & Zn & \(\upmu\)g/g & 10 & XRF \\ Hg & \(\upmu\)g/g & 0.0005 & AFS & Zr & \(\upmu\)g/g & 10 & XRF \\ La & \(\upmu\)g/g & 30 & XRF & Al\({}_{2}\)O\({}_{3}\) & \% & 0.05 & XRF \\ Li & \(\upmu\)g/g & 5 & AAS & CaO & \% & 0.05 & XRF \\ Mn & \(\upmu\)g/g & 30 & XRF & Fe\({}_{2}\)O\({}_{3}\) & \% & 0.05 & XRF \\ Mo & \(\upmu\)g/g & 0.4 & POL & K\({}_{2}\)O & \% & 0.05 & XRF \\ Nb & \(\upmu\)g/g & 5 & XRF & MgO & \% & 0.05 & XRF \\ Ni & \(\upmu\)g/g & 2 & XRF & Na\({}_{2}\)O & \% & 0.05 & XRF \\ P & \(\upmu\)g/g & 100 & XRF & SiO\({}_{2}\) & \% & 0.1 & XRF \\ \hline \end{tabular} Note: XRF: Xray fluorescence spectroscopy; AFS: atomic fluorescence spectroscopy; AAS: atomic emission spectroscopy; POL: polarography; IE: ion-selective electrode method; GF-AAS: graphite furnace-atomic absorption spectroscopy; COL/LCF: colomerty or laser catalytic fluorescence.  
\end{table}
Table 2: The elements, analytical methods, and detection limits of the RGNR.