Remobilization and element redistribution in volcanic-hosted massive sulphide deposits of the Skellefte district, northern Sweden: constraining the role of metamorphic fluid processes
Final Report Abstract
Metamorphosed volcanic-hosted massive sulfide deposits commonly display crosscutting vein-type mineralization with distinct enrichment in elements such as Au, Bi, As, Te, Se and Cu. The veinhosted mineralizations are also an important indicator of metamorphic fluid flow and pressuretemperature conditions. The genetic link between the vein-hosted mineralization and the massive orebodies is being debated, with metamorphic remobilization and shear zone controlled introduction being the end-member concepts. We report the results of a mineralogical and geochemical study of vein-hosted mineralization in four different metamorphosed volcanic-hosted massive sulfide deposits in the Skellefte metallogenic district, northern Sweden. The massive sulfide deposits cover different primary metal inventories (Cu-, Zn- and Au-As-rich ore types) and a range in metamorphic grade from greenschist- to higher amphibolite-facies. The results of this study, most importantly the spatially resolved trace element analysis of sulfide ore minerals, demonstrate that the vein-hosted mineralization is the product of metamorphic remobilization. The metals that are enriched in the vein-hosted mineralization (Au, Bi, Te etc.) are considerably depleted in the massive ores. Combining mineral geothermobarometry, fluid inclusion and stable isotope data, the pressure-temperature conditions during formation of the vein-hosted mineralization was reconstructed.
