The paper presents studies of the methane-rich fluid inclusions in the fresh peridotite from the Cambrian Yushigou ophiolite, the middle part of North Qilian Orogenic Belt. In situ analysis of laser Raman spectroscopy shows that these fluid inclusions are mainly composed of liquid or gaseous CH4+C (graphite) with minor components of N2, H2O, C2H6 and C3H8, representing the reductive C-H fluid speciation. Based on characteristic bands of graphite, the authors carry out fluid temperature estimates using the RSCM (Raman spectroscopy of carbonaceous materials). The calculated temperatures range from 430 to 590°C, which represents the minimum temperature for precipitation of graphite and indicates that CH4+C is abiotic origin and formed in the mantle environment.
