Combined Raman microprobe spectrometry and microthermometry of fluid inclusions in minerals from igneous rocks of the Gardar province (south Greenland)

Abstract

Raman microprobe spectrometry has been applied to analysis of the gaseous phase in individual fluid inclusions in minerals from alkalic igneous rock types and associated hydrothermal veins from the Gardar province, south Greenland. Quantitative analyses are given for CO 2, CH 4, C 2H 6, H 2 and H 2S. Traces of CO were observed in one CO 2 inclusion. In conjunction with data from microthermometry, the results permit calculation of the bulk chemical composition of entrapped fluids and evaluation of the possible pressure, temperature, oxygen fugacity and sulphur fugacity during entrapment of the individual fluid inclusions. Calculated oxygen fugacity values correspond to those of the NNO and QFM buffer reactions at temperatures of 300–400°C and pressures of 0.5–1.0 kbar. Calculated sulphur fugacity values are within the range of normal ore forming solutions (log f S 2 : −6 to −10).