Lithology, petrography and Cu occurrence of the Neoproterozoic glacial Mwale Formation at the Shanika syncline (Tenke Fungurume, Congo Copperbelt; Democratic Republic of Congo)

Two main episodes of sulphide mineralisation are distinguished in the Mwale Formation. The diagenetic episode consists of disseminated euhedral and framboidal pyrites. The hydrothermal episode is associated with Mg-metasomatism and characterised by low grade copper mineralisation that occurs (i) in veins filled with carbonate-chlorite and carbonate-quartz-chlorite-Cu sulphides, such as chalcocite, chalcopyrite and bornite, and (ii) as disseminated sulphides within the host rock. This second episode is late to post-orogenic and can be correlated with late brittle tectonics within the Lufilian arc. The other alteration types include silicification and potassic alteration; however, these alterations are not associated with mineralisation.