## 5 Discussion  
### Source of Ore-Forming Fluids  
The narrow range of \(\delta^{34}\)S values (4.5 to 8.0%.) of the gold-bearing pyrites at Jiaojia suggests a consistent source of ore-forming fluids. The Jiaojia pyrites showed significantly higher \(\delta^{34}\)S values than those of the mantle (0-3%) and continental crust. The values were, however, similar to the \(\delta^{34}\)S values of sulfides from metasomatized mantle [40; 41; 42; 43] (Figure 7). The subducted oceanic crust and the overlaid sediments were important factors resulting in high \(\delta^{34}\)S values in the metasomatized lithospheric mantle [45]. This implies that the ore-forming fluids of the Jiaojia gold deposit likely originated from a subducted oceanic plate-related metasomatized mantle. The \(\delta^{18}\)OSMOW and \(\delta\)D values of sericie from the Jiaojia gold deposit ores were reported to be 8.4% to 10.4% and \(-\)62% to \(-\)59%, respectively. The \(\delta^{18}\)O values (relative to the Standard Mean Ocean Water--SMOW) and \(\delta\)D values of K-feldspar extracted from the ores of the Jiaojia gold deposit fell within the ranges of 10.0% to 10.2% and \(-\)86% to \(-\)85%, respectively, as documented in reference [5]. For a single calcite specimen from the Jiaojia deposit, the \(\delta^{13}\)C values (relative to the Peedee Belemite--PDB) and \(\delta^{18}\)O values (relative to SMOW) were reported to be \(-\)6.4% and \(-\)3.4%, respectively, according to the findings in reference [46]. In terms of noble gas isotopes, the \({}^{3}\)He/\({}^{4}\)He ratios within the Jiaojia gold deposits spanned from 1.64 to 2.36 R/Ra, as reported in reference [47]. These geochemical signatures strongly suggest that fluids with a mantle origin had a significant influence on the gold mineralization process in the Jiaojia area. The isotopic compositions of oxygen, hydrogen, carbon, and helium provide crucial evidence for understanding the source and evolution of the fluids involved in the formation of the Jiaojia gold deposit, highlighting the substantial contribution of mantle-derived fluids to this mineralization event.  
Tellurium and Bi are relatively scarce chalcophile elements in the crust, with low abundances in the upper mantle [48]. Pyrite in the Jiaojia gold deposit is enriched in Te and Bi, indicating that ore-forming fluids may have had high concentrations of these elements. This suggests that the ore-forming materials may have originated from a deeper mantle or crustal source. Mantle or deep magmatic activity is closely associated with the formation of hydrothermal deposits related to Te [49]. Furthermore, [PERSON] et al. (2003) have identified extremely high anomalies of Te in iron-manganese nodules from a large number of marine sediments, ranging from 0.06 ppm to 205 ppm [50]. Subsequent studies have further analyzed and speculated that the partial melting of Te-rich marine sediments may be an important factor contributing to the high Te content in ore-forming fluids during the subduction of the oceanic crust [51]. These characteristics further support the hypothesis that the ore-forming fluids of the Jiaojia gold deposit originated from subducted oceanic plate-related metasomatized mantle.