## 3 Results and Discussion
### Geochemical Map of Li on Fixed-Value Method
The first level of the 19 levels corresponds to the Li concentration, ranging from the minimum to the first value (or 5 ug/g). The second level of the 19 levels corresponds to the Li concentration ranging from the first value (or 5 ug/g) to second value (or 8 ug/g), and so on. The last level of the 19 levels is corresponding to the Li concentration ranging from the 18 th value (or 1858 ug/g) to the maximum, like the description of the fixed values of Sn [21]. In order to better explain these levels, the 19 levels are mapped in six color tones according to those presented by [PERSON] et al. [21]. The levels of first to fifth are the low background areas in blue tones, corresponding to the Li concentrations ranging from the minimum value to 34 ug/g. The levels of sixth to ninth are high background areas in yellow tones, corresponding to concentrations less than 70 ug/g; the tenth to twelfth are low anomaly areas in pink tones less than 99 ug/g; the thirteenth to fifteenth are high anomaly areas in red tones less than 232 ug/g; the sixteenth to eighteenth in gray tones are less than 1858 ug/g, representing the mineralization in clay-type areas; and the nineteenth level is in black, with Li concentrations up to the cut-off grade of Li deposit reflecting the mineralization in hard-rock type areas. Although the implicit requirement of the \(\Delta\)lgLi between neighbor levels is not less than 0.1 [21], the fixed-value method of Li constructed here has \(\Delta\)lgLi values less than 0.1 from the fifth to the twelfth values. This is for two reasons. One is the 19 levels adopted and the other is the two values selected from the Li concentrations of the surface soils and stream sediments in China. The first value is close to the 25% cumulative frequency value of surface soils [32] and the 50% cumulative frequency value of stream sediments [14] in China, and is set as the fourth value of the 19 levels. The second value is the 99.5% cumulative frequency value of surface soils in China [32] and is set as the twelfth value in the 19 levels. During the mapping process, the GeoExpl 2013 software [14] was used to grid the original data with a grid spacing of 2 km. The interpolation method was performed using the nearest point model, and the data search mode was a circular domain with a radius of 5 km. The geochemical map was contoured based on the grid data using the fixed-value method of Li and illustrated in Figure 3.  
In Figure 3, only 14 levels are illustrated rather than 19 levels because of the Li concentration in the Mufushan area, which ranges from third level to sixteenth level. In Table 1 and Figure 2a, the quartiles of Q1, Q2, and Q3 are colored as the sixth, seventh, and eighth levels in Figure 3, and are located in the high background areas. The strata and Neoproterozoic intrusions (\(\gamma_{2}\)\({}^{3}\)) are mainly situated in the background areas with blue and yellow tones in Figure 3. With respect to the Mufushan complex, the early Yanshanian granodiorites (\(\gamma_{8}\)\({}^{2}\)) in the eastern area of the Mufushan complex  
Figure 3: Li geochemical map of Mufushan based on the fixed-value method. are mainly in pink, red, and grey tones, indicating the low anomaly, high anomaly, and mineralization in clay-type areas. The early Yanshanian granites (\(\gamma_{5}\)\({}^{2}\)) in the northeastern and the southwestern areas are mainly in yellow, corresponding to the high background areas. The first stage of the late Yanshanian granites (\(\gamma_{5}\)\({}^{3a}\)) in the central of the Mufushan complex are mainly in red, indicating the high anomaly areas of Li, while those in the northwestern area are mainly in yellow, reflecting the high background areas. These results indicate that the granitic intrusions of the first stage of the late Yanshanian (\(\gamma_{5}\)\({}^{3a}\)) in the central and northwestern parts of the complex may differ in detailed lithology.