Mambwe, P.,  Milan, L.,  Batumike, J.,  Lavoie, S.,  Jébrak, M.,  Kipata, L.,  Chabu, M.,  Mulongo, S.,  Lubala, T.,  Delvaux, D. & Muchez, P. 2017. ‘Lithology, petrography and Cu occurrence of the Neoproterozoic glacial Mwale Formation at the Shanika syncline (Tenke Fungurume, Congo Copperbelt; Democratic Republic of Congo)’. Journal of African Earth Sciences. Elsevier. DOI: 10.1016/j.jafrearsci.2017.02.021.  I.F. 1.326.

Article in a scientific Journal / Article in a Journal

The Mwale Formation that constitutes the base of the Nguba Group in the Neoproterozoic Katanga Supergroup has recently attracted renewed interest for copper mineral exploration. Field observations combined with detailed logging and petrography of the MWAS0001 drill hole at Shanika syncline in the Tenke Fungurume Mining District, show that the Mwale Formation consists of a vertical succession of glaciogenic, glaciomarine, glaciofluvial and glaciolacustrine deposits. Glaciomarine beds are typically a deposit in deep water marine environment by debris flow, induced by basin wide tectonic and glaciation influence. Glaciofluvial beds were deposited in a shallow water, fluvial delta environment while the glaciolacustrine environment is indicated by dropstones occurring in the laminated mudstone and rhythmites with dispersed clasts observed in the siltstone conglomerate. These beds are interlayered within the glaciogenic beds which characterised by variable composition with clasts (felsic, mafic and metamorphosed), very poorly sorted, angular, rounded to moderately rounded and supported in the sandy argillaceous or mud matrix. Two main episodes of sulphide mineralisation are distinguished in the Mwale Formation. The diagenetic episode consists of dissemination of euhedral and framboidal pyrites. The hydrothermal episode with the precipitation of low grade copper 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 in the host glaciogenic, glaciomarine and glacioafluvial beds. This second episode is late to post-orogenic and can be correlated with brittle tectonic recognized in the Lufilian arc. The other alteration types include silicification and potassic alteration; however, these alterations are not associated with mineralisation.