Halogen chemistry as an indicator of metamorphic fluid interaction with the Ponder pluton,Coast Plutonic Complex,British Columbia,Canada

During hydrothermal fluid activity associated with the intrusion of the Ponder pluton, Coast Plutonic Complex, British Columbia, Canada, the halogen composition of biotite, amphibole and apatite is controlled by the composition of the metamorphic fluid. The core of the pluton was not affected by infiltrating fluids, and the fluorine composition of biotite was controlled by the biotite Fe-Mg ratio. The edge of the cooling, crystallized pluton interacted with a chlorine-rich, fluorine-poor fluid which changed the halogen composition of biotite and amphibole. The composition of the metamorphic fluid derived from biotite and apatite compositions was relatively high in chlorine and low in fluorine. The concentration of chlorine in the metamorphic fluid increases towards the pluton, whereas fluorine remains constant. This suggests that the metamorphic fluid near the pluton had the greatest potential for masstransfer of metals.