The Tjarrojakka Fe-oxide Cu (-Au) occurrence, Kiruna area, northern Sweden

The Tjarrojakka area is located 50 km WSW of Kiruna and hosts several Fe-oxide and Cu (-Au) mineralisations. They are mainly hosted by strongly altered 1.9 Ga Svecofennian metaandesites overlain by metabasalts and show a spatial correlation to faults and shear zones. The Tjarrojakka Fe-oxide Cu (-Au) occurrence consists of an Fe-oxide deposit and a Cu (-Au) mineralisation located close to each other. The Fe-ore is characterised by a massive magnetite core surrounded by a magnetite-amphibole breccia and a low-grade Cu-mineralisation in the wall rock. The host rock has been affected by albite, K-feldspar and scapolite alteration. Chalcopyrite and bornite are the main ore minerals in the Tjarrojakka Cu-mineralisation occurring disseminated and in veinlets. The mineralised zone is dominated by potassic alteration expressed by the formation of K-feldspar. The footwall is characterised by magnetite-apatite veining spatially related to albitisation, while scapolite alteration accompanied by biotite is mainly developed in the hanging wall. The close spatial relation and the similarity in host rock and alteration suggest a genetic relation between the Tjarrojakka Fe-ore and the Tjarrojakka Cu-occurrence.