## 3 Results
### Chemical Composition  
To analyze the genesis of pseudotachyltyte and its relationship with the host rock, typical pseudotachyltyte and host rock samples were selected for electron probe composition  
Figure 11: EBSD for quartz in the host rock of pseudotachyltyte. **(A)** AF21-4-2; **(B)** AF21-4-3. analysis. To obtain pure chemical data of pseudotachylyte, this study focuses on the straight vein-type pseudotachylyte samples, which are widely distributed at outcrops, for analysis. In samples AF19-43D and AF19-44A, an SEM-EDS surface scan and electron probe major element analysis were conducted on the pseudotachylyte vein. A cross-sectional measurement was performed on AF19-43D (Figure 7), with approximately 20 measurement points for each profile, and two cross-section profiles on AF19-44A, with approximately 20 measurement points per profile (Figure 4). Based on the spatial distribution of pseudotachylyte and its relationship with the surrounding fractured granite, it is preliminarily concluded that the host rock on both sides of the pseudotachylyte vein is the parent rock of the melt. Major minerals, such as plagioclase and a small amount of amphibie in the parent rock, as well as plagioclase clasts in the pseudotachylyte, were analyzed using electron probe major element analysis (Figures 12 and 13). Figure 12: The results of electron microprobe and XRF for pseudotachylyte in AF19-43D. (**A–F**) Harker diagrams correlating Na\({}_{2}\)O, K\({}_{2}\)O, Al\({}_{2}\)O\({}_{3}\), CaO, FeO, and MgO versus SiO\({}_{2}\) content, respectively. The red fields designate plagioclase fragment compositions within pseudotachylyte, black fields delineate parent rock plagioclase compositions, green fields represent pseudotachylyte compositions, and blue fields correspond to hornblende phase chemistries. (**G**) Ternary phase diagram of the feldspar system (Ab-An-Or). Evidence from petrochemical analysis, combined with XRF results (Table 3), indicates the genetic relationship between pseudotachylyte and host rocks. Figure 13: The results of electron microprobe and XRF for pseudotachylyte in AF19-44A. (**A**–**F**) Harker diagrams correlating Na\({}_{2}\)O, K\({}_{2}\)O, Al\({}_{2}\)O\({}_{3}\), CaO, FeO, and MgO versus SiO\({}_{2}\) content, respectively. The red fields designate plagioclase fragment compositions within pseudotachylyte, black fields delineate parent rock plagioclase compositions, green fields represent pseudotachylyte compositions, and blue fields correspond to hornblende phase chemistries. (**G**) Ternary phase diagram of the feldspar system (Ab-An-Or). Plagioclase fragments within pseudotachyltyte exhibit highly consistent evolutionary trends in major elements (Na\({}_{2}\)O, CaO, and Al\({}_{2}\)O\({}_{3}\)) with wall rock plagioclase. For instance, a positive correlation was observed between Na\({}_{2}\)O and SiO\({}_{2}\) (Figures 12A and 13A). Negative correlations were observed between CaO and Al\({}_{2}\)O\({}_{3}\) and SiO\({}_{2}\) (Figures 12C,D and 13C,D). Overlapping An values (An33-41 for pseudotachylte versus An20-54 for wall rocks) indicate direct inheritance from wall rock minerals. The matrix of pseudotachyltyte shows significantly higher K2O content than the parent rocks, plagioclase and hornblende (Figures 12D and 13B), which is attributed to potassium feldspar decomposition in the parent rocks. FeO and MgO concentrations in the matrix exceed those in parent rock plagioclase but remain lower than in hornblende (Figures 12 and 13), indicating preferential incorporation of Fe-Mg components from mafic minerals (e.g., hornblende, biotite) during melting. Intermediate Na\({}_{2}\)O and Al\({}_{2}\)O\({}_{3}\) levels (between parent rock plagioclase and hornblende) and CaO consistency with plagioclase suggest multi-mineral phase mixing during melting. Pseudotachyltyte whole-rock SiO\({}_{2}\) content aligns with intermediate rocks (e.g., AF19-43D), while melt residues exhibit Si depletion and Na-Al-Ca enrichment. This reflects selective element migration during partial melting.