High-precision 40Ar/39Ar age of the gas emplacement into the Songliao Basin

Abstract

The problem of determining an exact isotopic age of hydrocarbon emplacement is complex because minerals suitable for dating with common isotopic methods are often lacking in the sedimentary domain. However, the igneous quartz from the Cretaceous volcanic rocks that host the gas reservoir in the Songliao Basin (northeastern China), contains abundant secondary fluid inclusions with high concentrations of K and high partial pressures of methane trapped during gas emplacement. Quartz with abundant K-rich fluid inclusions provides an excellent closed system well suited for