Argon isotopic studies of minerals in kimberlites, mantle xenoliths and diamonds, from selected southern African localities

Kimberlite-hosted minerals typically exhibit anomalously old ;Laser-probe ;Swartruggens phlogopite grains also display chlorine zonations, measured by a neutron activation technique and the laser probe. Fluorine contents, determined by electron microprobe were uniform. Halogen analyses on Premier xenolith phlogopite revealed minor variations. It is suggested that these halogen contents are controlled largely by the degree of equilibration with fluids derived from melt devolatilisation and infiltrating meteoric/hydrothermal waters.;Laser-probe spot-scanning analyses demonstrated that argon and chlorine migration proceeds dominantly by radial diffusion, although the effective "radius" for diffusion may be highly variable (;...