ARGON ISOTOPE GEOCHEMISTRY OF INCLUSION FLUIDS FROM GRANITE-ASSOCIATED MINERAL VEINS IN SOUTHWEST AND NORTHEAST ENGLAND

The methodology of 40Ar-39Ar dating, extended to include the analysis of chlorine, has been applied to the analysis of Ar-36, 40Ar, K, Ca, and CI in fluid inclusion-bearing quartz and fluorite veins from two areas of granite associated mineralisation in England. Crushing experiments have permitted the analysis of argon in the inclusion fluids. Stepped heating of the residues releases additional components from solid phases and provides approximate mineralisation ages for four samples from southwest England. These show that mineralisation extended for up to 80 Ma after the emplacement of the granite. The methodology of 40Ar-39Ar dating, extended to include the analysis of chlorine, has been applied to the analysis of Ar-36, 40Ar, K, Ca, and CI in fluid inclusion-bearing quartz and fluorite veins from two areas of granite associated mineralisation in England. Crushing experiments have permitted the analysis of argon in the inclusion fluids. Stepped heating of the residues releases additional components from solid phases and provides approximate mineralisation ages for four samples from southwest England. These show that mineralisation extended for up to 80 Ma after the emplacement of the granite.