## 3 Results and Discussion
### Geochemical Anomaly Map of Li Using Seven Levels of Classification Method  
Finding the threshold of anomaly is the key step in drawing a geochemical anomaly map, and it can be determined using a fixed value or unfixed values. With respect to the fixed value of the threshold, the geochemical anomaly map can be viewed as only part of the geochemical map. Therefore, the anomaly areas can also be recognized from high value areas on the geochemical map. However, the elemental concentrations in stream sediments, soils, and rocks are generally dependent on their lithology and weathering degrees [23; 24; 35; 36], so the threshold of anomaly should be determined on unfixed values. To draw the geochemical anomaly map on unfixed values, [PERSON] et al. [22] proposed a method called seven levels of classification, which adopts a fixed cut-off grade and unfixed backgrounds to classify the elemental concentrations. The determination of elemental background value is the key step in the seven levels of classification method. Although [PERSON] et al. [24] have proposed an empirical equation to describe the backgrounds of Li using samples from some weathering profiles in China, [PERSON] et al. [23] present a new equation using 851 records of elemental abundances including 379, 280, and 192 records of rocks, soils, and stream sediments, respectively, to describe the geochemical backgrounds of Li. Here, the new equation [23] is adopted along with the cut-off grade 1858 \(\mu\)g/g of Li in hard rocks to determine anomalies using the seven levels of classification method in the Mufushan area. The new equation is described as the following, for calculating conveniently. \[\lg c=-0.02630 xy^{2}z+0.03000 xyz^{2}+0.03540 xy+0.6425y+3.288\quad\text{for WIG}<20 \tag{1}\]  
\[\lg c=0.00001579x^{2}yz+0.001141y^{2}xz-0.9445y+0.3650z\quad\text{for }20\leq\text{WIG}<120 \tag{2}\]  
\[\lg c=0.1849 xy^{2}z+0.03382 xyz^{2}+0.6839 xyz-09414x-1.471y+1.070z\quad\text{for WIG}\geq 120 \tag{3}\]  
where \(c\) is the calculated geochemical background of Li in \(\mu\)g/g. The \(x\) in Equations (1) and (2) is WIG and is \(\lg\)(WIG) in Equation (3), where WIG is the weathering index of granite which is calculated in molecular proportions of the major oxides as WIG = 100[Na\({}_{2}\)O + K\({}_{2}\)O + (CaO-10/3P\({}_{2}\)O\({}_{5}\))]/(Al\({}_{2}\)O\({}_{3}\) + TFe\({}_{2}\)O\({}_{3}\) + TiO\({}_{2}\)). The \(y\) is \(\lg\)(Al\({}_{2}\)O\({}_{3}\)/Ti), where Al\({}_{2}\)O\({}_{3}\) and Ti represent their contents with units of wt% and \(\mu\)g/g, respectively. The \(z\) is \(\lg\)(K\({}_{2}\)O/SiO\({}_{2}\)) where K\({}_{2}\)O and SiO\({}_{2}\) represent their contents in wt%. The anomaly level values of the total of 3628 records are calculated firstly on the GBAL 1.0 software [22], which integrates the new equation to calculate the geochemical backgrounds of Li. Then, the values are gridded to contour the geochemical anomaly map. The gridding parameters such as grid spacing, search radius, and interpolation method are consistent with those in the geochemical map of Li aforementioned. The geochemical anomaly map of Li using the seven levels of classification method in the Mufushan area is illustrated in Figure 4.  
In Figure 4, the highest anomaly level is only fourth in the method of seven levels of classification. The anomaly areas determined in Figure 4 are mainly relative to the Mufushan granitic complex and the anomaly areas with higher levels are mainly located in the central and eastern areas of the complex. These results indicate that the mineralization of Li in the Mufushan area may have a close relationship with the Mufushan granitic complex genetically. With respect to the four Li deposits, Huangnidong in the center of the complex is located in the third level area, and the other known Li deposits (Duanfengshan in the northern area, Huangbaishan and Renli-Chuanziyuan in the southwestern area of the complex) are situated in the second level areas.