## 3 Sampling and Analytical Methods  
### Fluid Inclusion Analyses  
Samples were taken from the gold-bearing disseminated and stockwork-style fine-grained granitic ones for fluid inclusion analyses. Twenty-seven doubly polished sections were examined petrographically, of which twelve samples were picked for microthermometric and laser Raman spectroscopic measurement on quartzes. In disseminated fine-grained granitic ones, quartz grains occur as fine-grained (0.1 to 0.5 mm), anhedral to subhedral, and smoky gray aggregates intergrown with disseminated euhedral pyrite, magnetite, pyrrhotite, chalcopyrite, and molybden (Figure 5a), whereas in stockwork-style fine-grained granitic ones, they occur as euhedral fine-grained (0.2 to 0.7 mm) and dark gray veins intergrown with sulfide veins, which mainly consists of pyrite, magnetite, pyrrhotite, chalcopyrite, and molybden (Figure 5b). All of the samples had no deformation Figure 5a-c). The fluid inclusions trapped in the quartzes are generally minute (3 to 15 \(\upmu\)m), with many of occurring as clusters, whereas a few occur in isolation (Figure 5c). Figure 5: (**a–c**) Photomicographs under cross-polarized light showing the micro-texture characteristics  
of quartz grains for fluid inclusion studies: (**a**) fine-grained subhedral quartz grains intergrown with disseminated euhedral pyrite; (**b**) fine-grained subhedral quartz grains intergrown with sulfide vein; (**c**) fluid inclusions occurring as irregular, three dimensional clusters or in isolation. (**d-i**) Photomicrographs under plane-polarized light showing the characteristics of fluid inclusions from Xiawolong gold deposit: (**d**) type 1 inclusions (liquid H\({}_{2}\)O + vapor H\({}_{2}\)O) occurring as irregular, three-dimensional clusters; (**e**) type 2 H\({}_{2}\)O-CO\({}_{2}\) inclusions containing three phases (liquid H\({}_{2}\)O + liquid CO\({}_{2}\) + CO\({}_{2}\)-rich vapor); (**f**) type 3 daughter mineral-bearing inclusions coexisting with types 1 and 2 within the same field of view; (**g**) type 4 CO\({}_{2}\) inclusions consisting of liquid CO\({}_{2}\) and vapor CO\({}_{2}\); (**h**) type 1 inclusions with elongated and irregular shapes; (**i**) type 1 inclusions occurring along pseudo-secondary trails. Abbreviations: Qtz, quartz; Py, pyrite. Fluid inclusion microthermometry was performed on the Linkam THMSG 600 heating-cooling stage equipped with a Leitz microscope, the measured temperature range of which is from \(-\)198 \({}^{\circ}\)C to 600 \({}^{\circ}\)C, at the Fluid Inclusion Laboratories of China University of Geosciences, Beijing. For ensuring the accuracy of measurements, the synthetic fluid inclusions were selected to calibrate the stage. Firstly, the freezing experiments were performed so as to avoid experimentally induced stretching. Then, during the heating process, when near the clathrate-melting temperatures (T\({}_{\rm mL(clath)}\)) and the melting temperatures of the carbonic phase (T\({}_{\rm mL(CO2)}\)), the heating rate was 0.1-0.2 \({}^{\circ}\)C/min, and for the other measurements, it was 0.2-0.4 \({}^{\circ}\)C/min. Uncertainties were \(\pm\)0.1 \({}^{\circ}\)C and \(\pm\)1 \({}^{\circ}\)C for temperatures \(<\) 30 \({}^{\circ}\)C and \(>\)30 \({}^{\circ}\)C, respectively. After the microthermometry, Laser Raman (LRM) analysis was performed at the Fluid Inclusion Laboratories of China University of Geosciences, Beijing. The LRM analysis instrument, used to collect Raman spectra of the fluid inclusion trapped in the quartz grains, was a British Renishaw inVia Raman spectrometer. The light source used was an argon ion laser, with a wavelength of 514.5 nm, a laser power of 20 mW, and a laser beam spot size of approximately 1\(\upmu\)m. During the analysis, the counting time was 10 to 30 s, and the peaks were taken for one time point in the whole waveband of 100 to 4000 cm\({}^{-1}\), with the spectral resolution being 1 to 2 cm\({}^{-1}\).