Cu-Au mineralisation at Raitevarri, Karasjok greenstone belt, northern Norway

The Raitevarri Cu-Au deposit is within the Palaeoproterozoic Karasjok greenstone belt in northern Norway. The deposit is hosted by a calc-alkaline intrusion surrounded by the volcanosedimentary sequence of the greenstone belt. The probable sequence of alteration at Raitevarri is: 1) biotitisation, albitisation and sulphidation; 2) sericite-chlorite-pyrite alteration; 3) carbonatisation. Stages 1 and 2 predate peak deformation. Carbonatisation is either a distal phenomenon of stages 1 and 2 alteration or related to a later, syn- to post-peak regional deformation. Cu-Au mineralisation took place during stages 1 and 2. Nearly all veining in the mineralised rock is related to stage 2: quartz +/- pyrite and tourmaline-quartz +/- epidote +/- apatite +/- pyrite veins have distinct selvages of intense sericitisation and pyritisation. No Cu or Au introduction can be related to carbonatisation. A geochemical anomaly zoning pattern from the centre of the mineralised domain to the country rocks is: Au-Bi-Te, Cu(-Ag) -> Sn -> Mo +/- As -> Zn-Cd-Mo-Tl. The Mo and Zn-Cd anomalies occur in unmineralised areas. Metal association, alteration, mineralisation and geochemical anomalies detected best fit with a porphyry-Cu-Au style of mineralisation.