ABSTRACT

Three fumarolic gases, both gas and liquid phases, from the Kakkonda (Takinoue) geothermal area, northern Japan, were analyzed with a gas chromatograph-mass spectrometer to confirm the presence of C₅₊ hydrocarbons in the geothermal fluid of this area. C₅₊ hydrocarbons found in the analyses were mainly alkanes (C₅-C₁₅), aromatics (C₆-C₁₂) and cycloalkanes (C₆-C₈). Alkanes in the gas phase of one of the three samples show C₁₀-C₁₁ predominance, which has not been observed in other geothermal fields before. This clearly shows that compositions of heavier hydrocarbons from fumaroles in this area are not uniform. The variety suggests that up-flows in this geothermal circulation system take hydrocarbons with various degrees of thermal degradation up to the surface.