Geological observations in the Five-Klippes area, northwestern Katanga Copperbelt (Democratic Republic of the Congo)

Abstract

Surface mapping and exploration in the search license PR-2348, northwest of Kolwezi in the Neoproterozoic Katanga Copperbelt, focussed in the poorly documented Five-Klippes area, and showed that the Roan megabreccias occurring at the ground surface in the klippes are composed mostly of Musonoï, Mines (Kamoto Formation) and Kiubo rocks that form km- to mm-size blocks, fragments and matrix. The megabreccias are bordered by rocks of the Kiubo Formation, that are gently dipping south on the northern side, with few approximatively 10 m-size sharp refolding close to the megabreccia, while they are vertically dipping north on the southern side. A 262 m-long exploration core drilling performed under the megabreccia of one of the klippes highlighted a faulting marked by hydraulic-like fractured-deformed Kiubo rocks and by friction breccias. The Kiubo blocks, fragments and matrix in the megabreccia were teared out most likely from the southern limb of the fault. The faulting in depth is interpreted here as the roots of the ground surface megabreccia. This rupture and shearing is questioning the autochthonous character of the surrounding Kiubo and Mongwe rocks. It is suggested that, similarly as for the eastern Mamfwe anticline, the Nguba and Kundelungu groups succession in the klippes area constituted blocks thrust during the fold-and-thrust event of the Katangan orogeny, and extruded the megabreccias of the klippes before suture during the final stage of the northward compression. A nearly north-south transversal faulting and shearing crosscutting the limbs and megabreccias of the klippes marked the end of the compression. These new observations complement other similar ones in that region, and have important implications for future Cu-Co exploration.