Copper and the Congo

Copper and the Congo

The Central African Copperbelt (Katanga Basin) is the largest and most prolifically mineralized sediment-hosted copper province known on earth. Other provinces of this type include the Zechstein Basin (central Europe), the Kodaro-Udokan Basin (Russia), and the Paradox Basin (Utah) In 2011 the Democratic Republic of Congo was the 10th largest producer of copper worldwide, and with Zambia, the copper production from the Katanga Basin accounted for ~7% of global supply.

The copper deposits of the Katanga Basin are hosted by terrestrial and shallow marine sedimentary rocks (Katanga Supergroup) deposited 880-550 million years ago in an intracontinental basin and adjacent gulfs. Copper was deposited at low concentrations as a component of the material eroded from the continental land masses on either side. Periodically, the basin was isolated from the open ocean; water evaporated and salt was deposited among the sediments. Upon burial and deformation, notably during a phase of compression known as the Lufilian Orogeny, water trapped within the sediment was expelled and dissolved this salt. The resulting brine dissolved copper from the greater sedimentary package, and copper deposits formed where flow of this metal-rich liquid was focused and reacted with sulfur- or carbon-rich rocks to cause deposition of the dissolved copper.

Copper mineralization occurred at several times during the geological history of the region. Many of the well-known deposits that define the Copperbelt in Zambia and southern Congo formed early, during sedimentation, and broadly take the form of their host sedimentary layers. Elsewhere, discordant, high grade copper deposits formed in association with shallow brittle faulting that occurred late in the sedimentary history of the basin. Mawson West's Dikulushi and Kapulo projects both fit this latter description. Mawson's exploration prospects at Kinkumbi, as well as some of the satellite deposits near Dikulushi are stratabound share some features of the early-formed deposit styles.