5.3.2. Fluid Compositions

The compositions of the fluid inclusions within various veins were investigated by micro-Raman spectrometry using a Horiba XploRA PLUS instrument equipped with a 532 nm Ar laser and gratings set to 600 grooves mm<sup>−</sup><sup>1</sup> at Tohoku University, Japan. The qtz–mol and qtz veins are dominated by H2O, which might have occurred at the vapor or liquid phase, based on petrographic observations. Inclusions within the qtz–py veins that formed during the second stage might contain CH4 in the vapor phase (Figure 9b).
