LITHOSTRATIGRAPHICAL CORRELATION OF THE NEOPROTEROZOIC ROAN SUPERGROUP FROM SHABA (ZAIRE) AND ZAMBIA, IN THE CENTRAL AFRICAN COPPER-COBALT METALLOGENIC PROVINCE

New data on the lower Katangan sequences in Shaba (Zaire) and Zambia, collected during the 1989 and 1990 UNESCO-sponsored Geotraverses, reve al an important development on friction breccias throughout the Zambia n Copperbelt, which still remains poorly documented, and shows that th e Zairean and Zambian fades of the Roan Supergroup ran be correlated i n detail. As in Zaire, the deformation of Katangan terranes during the Lufilian orogeny produced important friction breccias in Zambia. Such breccias occur mostly between the upper part of the Lower Roan Superg roup and the Mwashya Group (R-4): above the shale with grit (RL3) at K onkola and Mindola, or within the Upper Roan Dolomite at Chambishi Sou th, Muliashi and Nchanga. At Mufulira, a typical fragment of Shaba Min es Group was observed within a major heterogeneous tectonic breccia. T his situation is similar to that reported at Kipapila fl;(Kimpe) and L ubembe in Zaire, both located on the same tectonic trend as Mufulira. However, a continuous stratigraphical succession can be observed in Za mbia from the basal unconformity to the Mwashya Group. Strong litholog ical similarities were found, formation by formation, between the Roan sequences of Zambia and Zaire. In particular, the complete Mines Grou p of Zaire (R-2) and the units from the RL6 to the RL4 in Zambia were deposited under comparable conditions of sedimentation and show a simi lar and correlatable evolution of lithologies. Furthermore, the overly ing Dipeta Group (R-3) of Zaire and the RL3, RU2/RU1 of Zambia, are eq ually comparable. Above the Upper Roan Dolomite, Lower Mwashya dolomit ic rocks, identical with the ones of Shaba, have been noted to occur i n Zambia in stratigraphical continuity with the typical black shales o f the Upper Mwashya. The correlation between the coarse clastics of th e Zambian footwall (RL7) and the red dolomitic argillites and sandston es of the Zairean R.A.T, (Roches Argillo Talqueuses: R-l) remains unce rtain. However these two sequences show some similarities suggesting a lateral fades change from high-energy siliciclastic sedimentation in Zambia, to quieter, less elastic and more carbonate rich sedimentation in Zaire. In agreement with the proposed lithostratigraphical correla tion volcanic and pyroclastic rocks, occurring both in Zaire and Zambi a in the Lower Mwashya, testify to a major period of igneous activity in the region. Intrusive rocks found in the Zambian Roan Group and in the Zairean Dipeta Group can probably be attributed to the same episod e of magmatism. Finally it can be shown that several copper-cobalt ore bodies are found at the same lithostratigraphical position in Zambia a nd Zaire: the Zambian ore shale corresponds to the classical Shaba ore bodies at the base of the Mines Group (R-2), the Nchanga upper orebody to the lower R-2.3 mineralization and the Zambian RL3 anomalous coppe r occurrences to those of the R-3.1.2 Dipeta unit.