Halogens in Eclogite Facies Minerals from the Western Gneiss Region, Norway

Ultra-high-pressure (UHP) eclogites and ultramafites associated fluid inclusions from the Western Gneiss Region, Norwegian Caledonides, have been analysed for F, Cl, Br I using electron-probe micro-analysis, time-of-flight secondary ion mass spectrometry neutron-irradiated noble gas spectrometry. Textures of multi-phase in cores silicate grains indicate formation during growth host crystal at UHP. Halogens are predominantly hosted by with a minor component mineral such as biotite, phengite, amphibole apatite. The reconstructed composition contains between 11.3 12.1 wt% 870 8900 ppm 6 169 I. F/Cl ratios efficient fractionation F Cl hydrous crystallisation. Heavy halogen higher than modern seawater up to two orders magnitude Br/Cl three I/Cl. No correlation exists or I, while show good correlation, suggesting that behaved differently subduction. Evolution is similar trends defined eclogitic hydration reactions evaporation, indicating preferential removal UHP metamorphism. This study, analogy, offers field model an alternative source (continental crust) mechanism (metasomatism partial melts supercritical fluids) which halogens may be transferred stored sub-continental lithospheric mantle transient subduction continental margin.