Rhenium i Aitik Cu-Au-Ag-(Mo) malmen

The low-grade and high tonnage Aitik Cu-Au-Ag (Mo) deposit, the Salmijärvi deposit, and the Liikavaara deposit, which are situated at the mining district of the Norrbotten county, northernmost Sweden, are regarded as a porphyry deposit. Geologically the three deposits are situated in the continental domain of northern norrbotten, which comprises supracrustal series of meta-volcano-sedimentary rocks of paleoproterozoic age. These three deposits contain minor amounts of molybdenite. Rhenium, which is a unique element discovered back in 1925, naturally occur incorporated within the structure of molybdenite. The aim of this study was to determine the rhenium concentration within molybdenite and the genetic implication of the rhenium variation in different settings of molybdenite grains. In this study it has been possible to see significant variations of rhenium with different setting of molybdenite grain samples. In the Aitik deposit the rhenium concentration of molybdenite are higher in the quartz monzodiorite intrusive body (QMD) and in the quartz-muscovite-sericite schist than in the garnet-bearing biotite schist. In addition, the high rhenium-containing molybdenites are associated with rocks that are intensively sericite and biotite altered. Molybdenite in the Salmijärvi deposit contains an elevated amount of rhenium, especially in those rocks that are strongly altered by amphibole and biotite. Furthermore, the difference in degree of modification process that these two deposits seems to have undergone might have had an impact on the rhenium concentration of molybdenite, which has been seen from the relationship between the rhenium concentration in molybdenite and the crystal habit of the studied molybdenite grains.Based on the average rhenium concentration of the analysed molybdenite grains, the three studied deposits are similar to those Cu-Mo porphyry deposits of the world that are crustal in origin and show a sharp contrast in rhenium content of molybdenite with those Mo-Cu porphyry deposits of Climax-type.Validerat; 20111206 (anonymous