## 3 Results and Discussion
### Geochemical Map of Li on Fixed-Value Method  
To contour the geochemical map objectively, [PERSON] et al. [20] and [PERSON] et al. [21] proposed the fixed-value method for Cr and Sn, respectively. According to the construction of the fixed-value method [20,21], a fixed-value method on Li is proposed here on 19 levels according to the method presented by [PERSON] et al. [21] and listed in Table 2 along with the values of the fixed-value method on Sn. In the fixed-value method on Li, to contour the geochemical map, Li concentrations are divided into 19 levels on 18 fixed values which range from 5 \(\mu\)g/g (corresponding to the detection limit) to 1858 \(\mu\)g/g (corresponding to the cut-off grade of Li deposit in hard-rock type). The first value is 5 \(\mu\)g/g, which is the detection limit of the RGNR project [12,14], although the detection limit of Li was 1 \(\mu\)g/g in the NMPRGS project [31]. The second value \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Parameters** & **Data** & **Minimum** & **Lower Quartile** & **Median** & **Upper Quartile** & **Maximum** & **Average** & **Standard Deviation** \\  & **Amount** & **(Q1)** & **(Q2)** & **(Q3)** & **Maximum** & **(Avg)** & **(Std)** \\ \hline Li & 3628 & 10.2 & 39 & 47.3 & 59.1 & 279 & 54.8 & 29.6 \\ lgLi  & 3458 & 1.305 & 1.587 & 1.668 & 1.754 & 2.064 & 1.677 & 0.129 \\ Li [FOOTNOTE:]Footnote : Note: The unit is \(\mu\)g/g of Li concentrations.[ENDFOOTNOTE] & 3458 & 20.2 & 38.6 & 46.6 & 56.8 & 116 & 47.5 & 1.35 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The statistical parameters of Li and lgLi in the Mufushan area. Figure 2: Histograms of Li concentrations with box plots of stream sediments in Mufushan area. (**a**) All data; (**b**) outliers excluded. is 8 ug/g, which is the 0.5% cumulative frequency value of surface soils in China [32]. The third value is 17 ug/g after the 13 ug/g, corresponding to the 2.5% cumulative frequency value of surface soils in China [32], and 21.5 ug/g, corresponding to the 25% cumulative frequency value of stream sediments in China [14]. The fourth value is 29 ug/g after 27 ug/g, corresponding to the 25% cumulative frequency value of surface soils in China [32] and 30 ug/g, corresponding to the 50% cumulative frequency value of stream sediments in China [14]. The sixth value is set at 40 ug/g after the 40 ug/g, corresponding to the 75% cumulative frequency value of surface soils in China [32], and 40 ug/g of the 75% cumulative frequency value of stream sediments in China [14]. Based on the sixth and fourth values, the fifth value is interpolated as 34 ug/g. The eighth value is set at 62 ug/g after the 62.2 ug/g, corresponding to the 95% cumulative frequency value of stream sediments in China [14] and 65 ug/g of the 97.5% cumulative frequency value of surface soils in China [32]. Based on the eighth and sixth values, the seventh value is interpolated as 50 ug/g, which is close to the 46.4 ug/g of the 85% cumulative frequency value of stream sediments in China [14]. The twelfth value is 99 ug/g, which is the 99.5% cumulative frequency value of surface soils in China [32]. Based on the twelfth and eighth values, the ninth, tenth, and eleventh values are interpolated as 70 ug/g, 78 ug/g, and 88 ug/g, respectively. The fifteenth value is 232 ug/g (corresponding to 0.05% of Li\({}_{2}\)O), which is the cut-off grade of the clay-type Li deposit [33]. Based on the fifteenth and twelfth values, the thirteenth and fourteenth values are interpolated as 132 ug/g and 175 ug/g, respectively. The seventeenth value is 930 ug/g (corresponding to 0.2% of Li\({}_{2}\)O) which is the cut-off grade of Li as an associated resource [34]. Based on the seventeenth and fifteenth values, the sixteenth value is interpolated as 460 ug/g. The eighteenth value is 1858 ug/g (corresponding to 0.4% of Li\({}_{2}\)O) which corresponds to the cut-off grade of the Li deposit in hard-rock type areas [34]. Based on the above 18 fixed values, the concentrations of Li can be classified into 19 levels on the geochemical map of Li.