<P> The Faymar Gold Property, near Timmins Ontario, is cross-cut by two quartz-carbonate veins. Isotopic measurements of carbon species in fluid inclusions in these quartz-carbonate veins, reveal the presence of CO2 and other light carbon species (eg. CH4). The inclusion contents were liberated using thermal decrepitation. The results obtained are found to vary quite significantly with various periods and temperatures of heating. The most useful results were obtained from samples heated for 5 minutes at 550 °C. The short heating period reduces fractionation and reaction effects. Mass spectrometer measurements of the carbon isotopes reveal that the CO2 and total carbon in the inclusions are characterized by a δ13c of -3.O and -4.7 respectively. A magmatic source for the fluids most easily explains these values. Petrographic observations indicate that secondary inclusions dominate. Thus, the isotopic measurements are of fluids which post-date the deposition of the quartz-carbonate or at least represent a late stage of this process. Since the mineralization in the veins also appears to be secondary to the quartz-carbonate (ie. in fractures), it is possible that the carbon species in the inclusions are distinct of the mineralizing fluids. </p> / Thesis / Bachelor of Science (BSc)