## 5 Application
### Application on Stream Sediments and Soils  
The data of areal stream sediments and soils were extracted from the database of the regional geochemical survey in the southern Sichuan area, which is a generally flat terrain with low mountains. The study area extends ca. 280 km from the east to the west, corresponding to the longitude from E 103.48\({}^{\circ}\) to E 106.35\({}^{\circ}\), and ca. 142 km from the north to the south, corresponding to the latitude from N 28.70\({}^{\circ}\) to N 29.98\({}^{\circ}\), covering an area of ca. 39,760 km\({}^{2}\) (Figure 4). The exposed strata in the study area mainly include formations from the Quaternary, Cretaceous, Jurassic, Triassic, Permian, and Cambrian, from the younger to the older strata (Figure 4). The Quaternary stratum occurs in the northwestern region. The Jurassic strata are spread out across a large area, covered by the Cretaceous stratum sporadically. The Upper Triassic stratum (T\({}_{3}\)) extends in strips in the NE-SW direction in the east, and in sheets in the central and western divisions of the study area. The Permian and Cambrian strata are exposed only in the western region, and only in small areas. The lithology of these strata is described briefly in Figure 5 as notes. Only a small area of granite outcrops appears in the western regions. The faults in the study area are mainly distributed in the Permian strata in the western part of the area, and in the Jurassic and Triassic strata in the central part. Figure 4: Regional geological map of southern Sichuan area (Modified after the 1:1,000,000 geological map of H48 from China Geological Survey by the software of MapGis 6.7). (1) Quaternary: gravel, grit, sand and clay; (2) Cretaceous: lithic sandstone, fine-silt sandstone, mudstone; (3) Upper Jurassic: conglomerate, sandstone, siltstone, mudstone; (4) Middle Jurassic: mudstone, siltstone, sandstone intercalated with limestone; (5) Lower Jurassic: mudstone, sandstone, siltstone intercalated with limestone, marl; (6) Upper Triassic: feldspar quartz sandstone intercalated with siltstone; (7) Lower-Middle Triassic: lower conglomerate, sandstone, shale, purple mudstone, limestone, upper dolomite, limestone; (8) Permian: lower sand shale, limestone, dolomite, middle basalt, upper sandstone, sand shale, mudstone, coal; (9) Cambrian: shale, siltstone, sandstone, limestone, dolomite, bottom phosphorus; (10) Granite; (11) Faults; (12) Location of the Zi208 drill well. Elemental data of 8813 stream sediment and soil samples in the southern Sichuan area were extracted from the database of the regional geochemical survey. The minimum, lower quartile, median, upper quartile, maximum, mean, and standard deviation of contents of major oxides, CaO/MgO, and WIG of the 8813 samples are listed in Table 4.  
From the statistical parameters of the contents of SiO\({}_{2}\) and CaO (Table 4), the siliceous component (Type 1) and carbonate component (Type 5 or Type 6) can be determined in the study area. In order to better analyze the distribution of classified types in the study area, a geochemical map was drawn based on the classified type numbers. The data of the classified type numbers were gridded firstly with an interval space of 2 km on a scale of 1:200,000 using the nearest point interpolation method with a search radius of 3 km [29]. Then, red, pink, yellow, green, light blue, and dark blue colors were used as the legend to represent the classified type numbers from 1 to 6, respectively. Finally, the grid data were contoured to draw the geochemical map (Figure 5) of the classified results using the new proposed method, using the software GeoExpl 2013 [24]. The southern Sichuan area contains all six types of components based on the new proposed classification method, of which type 3 (silicate component) is distributed in a large area, followed by type 2 (felsic component) and type 1 (siliceous component). Conversely, type 4 (calcsilicate component), type 5 (dolomitic component), and type 6 (calcare