Central African Copperbelt Research Articles

Chalcopyrite, sphalerite, and pyrite chemistry in stratiform sediment-hosted Cu(-Co) metallogenic districts: trace element characteristics and factors controlling polymetallic mineralization

AbstractStratiform sediment-hosted Cu deposits are significant global sources of Cu and other important metals. The Polish Kupferschiefer produces Ag, Au, Pb, Ni, Se, and Re as by-products, whereas Co is one the of most important metals in the stratiform sediment-hosted Cu-Co deposits of the Central African Copperbelt and the Namibian Dolostone Ore Formation deposit. This study combines new and published laser ablation inductively coupled plasma mass spectrometry sulfide trace element data from these stratiform sediment-hosted copper districts. All the investigated districts exhibit sulfides occurring as disseminations and within later veins. Chalcopyrite, sphalerite, and pyrite trace element contents vary significantly between the metallogenic districts as well as between different ore stages. Random Forest discriminates the stratiform sediment-hosted Cu(-Co) districts based on trace element geochemistry. High Ag and Tl in chalcopyrite is attributed to the Polish Kupferschiefer, Ga and Ge to the Katanga Copperbelt, and Zn and In to the Dolostone Ore Formation deposit. Sphalerite from the Polish Kupferschiefer and the Dolostone Ore Formation deposit can be distinguished on the basis of the Fe and Cd contents. Cobalt and As are significantly elevated in pyrite from the Katanga Copperbelt and Mn in pyrite from the Dolostone Ore Formation deposit. The trace element contents also show that the stratiform sediment-hosted Cu(-Co) deposit sulfide data cluster separately from other deposit types. The variation in sulfide trace element contents between the three investigated stratiform sediment-hosted Cu(-Co) districts suggests that sulfide chemistry is related to the geology of the host basin and the nature of the underlying basement, which includes preexisting ore occurrences.

Microtectonics and fluid evolution in the Katanga Supergroup (Tenke Fungurume Mining District): Evidence of pre- to post-orogenic Cu-Co mineralization in the Central Africa Copperbelt

The sediment-hosted stratiform copper-cobalt deposits in the Central African Copperbelt (CACB) are renowned for their resource potential, encompassing Cu-Co (Ni, U) and Cu-Zn-Pb (Ag, Ge, Mo, Cd) mineralization. Microstructural and microthermometric analyses of carbonate-quartz veins from the Tenke Fungurume mining district, situated in the central part of the Katanga Copperbelt (KCB), have delineated a pre- to post-folding paragenesis of vein formation and hypogene Cu-Co ore mineralization. The mineralization primarily consists of chalcopyrite, chalcocite, carrollite, and bornite.Pre-folding veins comprise bedding-normal veins related to the extension stage, occasionally linked with mullion development during the following compressional stage, as well as bedding-parallel beef veins. Syn-folding mineralization manifests as saddle reef veins within fold hinge zones, fracture-filling veins aligned with tangential longitudinal strain in hinge zones of folded bedding-parallel veins, thin veinlets forming parallel to an axial-planar and shear-band cleavage, and bedding-parallel shear veinlets with oblique fiber orientations. The post-folding Cu-Co mineralization consists of veins that cross-cut earlier veins and folds.Microthermometric analysis of fluid inclusion assemblages from the pre-, syn-, as well as post-folding veins reveals the presence of different fluid types. A high-temperature (180–340 °C) and high-salinity (27–52.5 wt% NaCl + (KCl) eq.) fluid was responsible for the Cu-Co mineralization during the pre- to syn-folding stages. A hypersaline fluid (27.0–42.1 wt% NaCl eq.) with a broad range in temperature (45–387 °C) circulated during the post-folding stage of the Lufilian orogeny. A fluid exhibiting low to moderate homogenization temperatures (28–215 °C) and low to moderate salinity (3.4–23.0 wt% NaCl eq.) is related to fluid circulation during the post-Lufilian epoch. The wide range and variations in salinity of these three fluid types associated with Cu-Co mineralization provide evidence for a multistage fluid flow and a complex hydrothermal system linked to the deposition of Cu-Co ores within the Tenke Fungurume Mining District and the broader Katanga basin. This hydrothermal system has operated during diagenesis, the basin development stage to the Lufilian orogeny and the subsequent post-Lufilian period.

Depth estimation of pre-Kalahari basement in Southern Angola using seismic noise measurements and drill-hole data

The remote Southern region of Angola is covered by siliciclastic Kalahari Cenozoic formations that host underground aquifers of great importance to local populations affected by water scarcity problems. These aquifers are well developed where Kalahari sands reach appropriate thicknesses. On the other hand, at the eastern end of this area, regional aeromagnetic data recently acquired suggested the possibility of the continuity of the geological structures of the Lufilian Arc, sited in the nearby Zambia and Congo, southwestwards into Angola under the Kalahari formations. Once the Lufilian Arc is associated with the presence of the so-called Central African Copperbelt, this possibility increased the interest in determining the depth to Pan-African rocks under the Kalahari basin. To estimate the thickness of Kalahari formations in this area of difficult access and poor logistics, an expedited and non-invasive geophysical method was needed. Seismic noise and the single-station Nakamura technique were chosen, but due to the large distance of the study area from the ocean, one of the major sources of seismic noise, a test survey was acquired in the Cuvelai region to assess the signal quality, where the data was calibrated using available drill-holes. >170 points of seismic ambient noise were later acquired and the horizontal/vertical (HVSR) amplitude versus frequency curves were 1D inverted for the best velocity/density model for each station. The results were compared with 1D inverted legacy vertical electrical soundings reprocessed and validated in this work, showing similar depth-to-basement, while interpreted velocities/densities of geological formations were sampled and confirmed with measurements. A depth-to-basement map was produced using seismic information, mechanical soundings, and geological information. Despite the relatively reduced geographical area covered, the map presents valuable information for hydrogeology and mineral exploration purposes and agrees with a previously available coarser map of Kalahari thickness and with observations from geological surveys simultaneously conducted at the time of the seismic surveys.

Integration of Large Multielement Geochemical, Aeromagnetic, and Gravity Data to Geologically Map a Largely Covered Area: A Case Study from the Central African Copperbelt in Northern Zambia

Abstract This study provides a method to map lithology, stratigraphy, and structures in areas with limited outcrop using mineral exploration data from multielement soil geochemical surveys, airborne and ground geophysical surveys, and drill hole data sourced from multiple exploration companies and campaigns. The 45- by 50-km study area is located in the southern portion of the Congolese Copperbelt, where the regional geology, structure, and overall basin architecture were not well understood, partly due to thick saprolite cover. The results demonstrate that the integration of such data sets allows the creation of a geologically coherent map, which can then be used to investigate basin architecture and identify basin-forming structures.

Diagenesis and mineralization in the Central African Copperbelt, implications from the reflectance of pyrobitumen and Kübler (illite crystallinity) index

The Central African Copperbelt stands out as one of the world's largest sediment-hosted Cu-Co provinces, contributing to over 60% of global Co production. A comprehensive basin analysis approach is imperative for unraveling the ore-forming processes, encompassing an understanding of the diagenesis or metamorphism that the mineralized rocks underwent. In this study, two types of pyrobitumen (burial related and burial plus hydrothermal related) reflectance values have been measured, which record maximum temperatures during deep burial and hydrothermal imprint. The calculated temperatures provide important information about the maximum burial and hydrothermal fluid temperatures in distinct regions of the Copperbelt. The average burial related pyrobitumen reflectance for Nkana, the southeastern part of the Copperbelt, ranges between 3.43 and 3.75% BRr, indicating a maximum burial temperature of about 240 °C. Moving towards the central part of the Copperbelt at Luiswishi, the average pyrobitumen reflectance varies between 2.65 and 2.87% BRr, with calculated maximum burial temperatures reaching about 220 °C. In the northwestern part (Tenke Fungurume mining district, TFMD), the maximum burial temperatures decrease to approximately 200 °C, based on the calculation of pyrobitumen reflectance at 2.10% BRr. This decreasing temperature trend from southeast to northwest corresponds to the observed decrease in metamorphic grade across the Copperbelt, ranging from amphibolite and upper greenschist facies in the Zambian part to prehnite-pumpellyite facies in the Congolese Copperbelt. The temperatures calculated during maximum burial, especially at the Nkana ore deposit, are lower than those previously proposed based on the mineralogy of the rocks, i.e. upper greenschist facies. However, the latter does correspond to the temperatures reached by the mineralizing fluids in this area and thus rather reflects the alteration assemblage and temperature. The average burial plus hydrothermal related pyrobitumen reflectance measured at TFMD ranges between 3.06 and 5.36% BRr, indicating calculated average temperatures of 300–350 °C. These temperatures align with those recorded for the late diagenetic to syn-orogenic mineralization by fluid inclusion microthermometry (180–340 °C) at TFMD. The data suggests a pervasive migration of hydrothermal fluid through the rocks, contributing to the observed pyrobitumen reflectance. The illite crystallinity of the examined samples is notably high. At Nkana, the KI values range between 0.10 Δ°2θ and 0.22 Δ°2θ, for Luiswishi between 0.12 Δ°2θ and 0.24 Δ°2θ, for Kamoto between 0.17 Δ°2θ and 0.23 Δ°2θ, for TFMD between 0.17 Δ°2θ and 0.25 Δ°2θ, which indicates all these samples were placed in epizone, with only a few in anchizone. This high value could be attributed to two potential factors: the admixing of detrital muscovite to the sediments or the influx of potassium due to the pervasive alteration throughout the Copperbelt, but the latter one is less likely since the selected samples show no evidence of alteration.

Biomarker signatures and depositional environment of ore-bearing black shale in the Luishia Cu–Co deposit, Democratic Republic of Congo: Implications for regional copper mineralization

The Central African Copperbelt is a globally important sediment-hosted stratiform copper cluster, with regional Cu–Co deposits controlled by Neoproterozoic rift basin. Ore formation in the Copperbelt involves multiple stages of mineralization during diagenesis, basin inversion, and collisional orogeny. Understanding the depositional environment of ore-hosting rocks is crucial for revealing the geological settings and pre-orogenic ore genesis. This paper presents a biomarker study focusing on the ore-bearing black shale in the Luishia Cu–Co deposit, Democratic Republic of Congo. The research investigates thermal maturity, source, and depositional environment of organic matter through rock organic carbon and pyrolysis analysis, chloroform bitumen “A” group component analysis, as well as saturated hydrocarbon gas chromatography-mass spectrometry (GC-MS) analysis. The results indicate significant thermal maturation of organic matter in Luishia black shale. Bacteria are identified as the primary source of organic matter followed by red algae and green algae. The sedimentary environment is characterized by a restricted rift basin under shallow marine conditions with a stratified water column. The processes of bacterial sulphate reduction (BSR) and thermochemical sulphate reduction (TSR) significantly influence the mineralization during diagenesis and basin inversion, respectively. Enhanced thermal maturity promotes methane generation which plays a role in reducing anhydrite and subsequently precipitating ore minerals. The findings have important implications for regional exploration strategies.

Geochemistry of Terrestrial Plants in the Central African Copperbelt: Implications for Sediment Hosted Copper-Cobalt Exploration

Mineral exploration has increasingly targeted areas covered by in situ or transported overburden for shallow to deep-seated orebodies. It remains critical to develop better means to detect the surficial chemical footprint of mineralized areas covered by thick regolith. In such settings, plant geochemistry could potentially be a useful exploration tool, as different plant species have varying degrees of tolerance to metal enrichment in the soil. This review provides insights into the geological and geochemical controls on metal accumulation patterns in soil–plant systems of the Central African Copperbelt. In addition, it highlights the opportunities for integrating the geochemistry of terrestrial plants in emerging exploration technologies, identifies research gaps, and suggests future directions for developing phytogeochemical sampling techniques. This review was conducted using reputable online scholarly databases targeting original research articles published between January 2005 and March 2023, from which selected articles were identified, screened, and used to explore current advances, opportunities, and future directions for the use of plant geochemistry in sediment hosted Cu–Co exploration in the Central African Copperbelt. Various plant species are recognized as ore deposit indicators through either independent phytogeochemistry or complementary approaches. In the Central African Copperbelt, the successful application of hyperaccumulator species for phytoremediation provides the basis for adopting phytogeochemistry in mineral exploration. Furthermore, current advances in remote sensing, machine learning, and deep learning techniques could enable multi-source data integration and allow for the integration of phytogeochemistry.

Shameful or shameless? Anxieties about mothers and women's autonomy on the Central African Copperbelt, 1956–1964

AbstractThis article deals with anxiety about and the shaming of modern urban mothers and wives on the mines of the late colonial Central African Copperbelt. Women's various labours and public presence lead to ambivalent depictions, such as the ‘careless mother’, that were part of a broader array of anxieties about women's autonomy on the mines. However, urban women rejected such labelling and resisted the isolation of modern motherhood. Instead, they created networks of mutual support and solidarity, they publicly shamed their failing breadwinners, supported one another financially, emotionally and through expressing solidarity in the press, thus seeking economic independence where possible.

Growth and Stability of Stratiform Carrollite (CuCo2S4) in the Tenke-Fungurume Ore District, Central African Copperbelt

Abstract Carrollite (CuCo2S4) is the main ore mineral of the critical battery metal cobalt, yet, surprisingly, detailed characterization of its thermodynamic properties and of its trace element contents remain sparse in the scientific literature. To fill these knowledge gaps, we generated the first thermodynamic data set for carrollite using well-characterized samples obtained from the stratiform sulfide mineralization style at Fungurume 88 deposit in the Democratic Republic of Congo. Detailed mineralogical investigation of these same samples suggests that carrollite has limited ability to incorporate other ‘sweetener’ elements (except Cu and Ni) by substitution mechanisms. Modeling using CHNOSZ 2.0.0. software and an integrated Cu-Co-S-O thermodynamic data set provides insights into the stability of carrollite relative to other Co-bearing minerals under physicochemical conditions relevant to the Central African Copperbelt. Further exploration of these models indicates that dropping redox potential in the mineralizing system is insufficient to explain the mineral-scale and deposit-scale zonation patterns commonly observed in Cu-Co deposits of the Central African Copperbelt. Instead, factors such as increasing pH, decreasing T, decreasing sulfur activity, or some combination of changing physicochemical parameters may need to be invoked to explain these zonation trends. At the Fungurume 88 deposit, the absence of linnaeite (Co3S4) suggests that ore precipitation occurred at temperatures cooler than 211 °C. From our pH-logfO2 diagrams, and relative to higher temperatures, such a lower T regime is marked by a greater degree of offset between the modeled Cu and Co solubility contours, thus facilitating a more differentiated and zoned distribution of these two metals at the deposit scale. Our models are offered to the geoscience community as exceptionally useful tools for modeling and visualizing the Cu-Co-S-O systematics and may be applied to a variety of geological and geometallurgical questions in the Central African Copperbelt and other deposits elsewhere.

Genesis of sediment‐hosted copper and silver mineralization at the Omatapati prospect, Kaoko Belt, Opuwo district, Kunene region, Namibia

AbstractThe Omatapati copper and silver prospect within the Kaoko Belt is located in the Opuwo district, Kunene region, Namibia. The prospect is hosted by dolomite and interbedded argillites of the Neoproterozoic Devede Formation, the Ombombo Subgroup. An ore body is exposed in shallow artisanal mining pits and drill‐cores of the prospect have grades of 0.4 to 5.2 wt% Cu, and 23 to 312 g/t Ag. The prospect was formed by both hypogene and supergene mineralization processes. The hypogene mineralization occurred in three stages. Stage 1 is represented by calcite veins containing chalcopyrite, bornite, sphalerite and galena. Stage 2 consists of quartz and calcite veins with chalcopyrite and bornite. Stage 3 consists of quartz‐calcite‐barite veins with chalcopyrite. The veins of stages 1 and 2 are subparallel or discordant to the foliation of argillites, and those of Stage 3 are NE‐striking and steeply dipping in the brecciated dolostone and argillite. The mineralization stages 1, 2, and 3 are overprinted by supergene chalcocite, digenite, annite, covellite, malachite, delafossite, hematite, and goethite. The supergene process forms a semi‐massive chalcocite‐covellite zone, which extends from the surface to ~50 m depth. The veins show average concentrations of 2.1 wt% Cu, 80 ppm Ag, and 532 ppm Pb for the stage 1, 3.1 wt% Cu, 118 ppm Ag, and 66 ppm Pb for the stage 2, and 18.6 wt% Cu, 675 ppm Ag, and 565 ppm Pb for the Stage 3 with supergene overprinting. Silver occurs as impurity in supergene chalcocite (6303 ppm Ag), digenite (4425 ppm Ag), and covellite (3060 ppm Ag). Fluid inclusions in quartz and calcite revealed that the hypogene mineralization occurred under a pressure >7–8 MPa. Temperatures of ore formation of the stages 1, 2, and 3 were >145–155 °C, >290–300 °C, and >190–230 °C, respectively. Large variation of salinities in each fluid inclusion assemblage suggests fluid mixing and dilution processes. Fluid inclusion gas compositions in the Stage 3 have weighted means of 98.98 mol% H2O, 0.75 mol% N2, 0.52 mol% CO2, 0.02 mol% CH4, 0.0021 mol% Ar, 0.0009 mol% H2S, and 0.00006 mol% He and indicate a signature of magmatic fluids mixed with meteoric waters or seawater. δ34SCDT values of sulfides in the stages 1, 2, and 3 in the prospect have three data clusters, (1) near 0 ‰ of chalcopyrite in the stages 1 and 2, (2) near −11 ‰ of bornite in the stage 2, and (3) +5 to +11 ‰ of the supergene chalcocite and covellite. Modes of occurrence of ores, fluid inclusions and sulfur isotope data show that the prospect is likely the same type as sediment‐hosted copper‐silver deposits with veining found in the Central African Copperbelt.

Living for the City: Social Change and Knowledge Production in the Central African Copperbelt

Living for the City: Social Change and Knowledge Production in the Central African Copperbelt

The role of supermountain belts and climatic controls on the genesis of copper deposits in the Kupferschiefer and the Central African Copperbelt

Sedimentary rock–hosted stratiform copper deposits are the world’s second largest source of copper and the largest source of cobalt, with about 73% of the copper occurring in two basins: the Katangan Basin (Central African Copperbelt) and the Permian Basin (Kupferschiefer). Why these two sedimentary basins are so highly endowed in copper is puzzling because sedimentary rock–hosted stratiform copper deposits have formed since the Paleoproterozoic and they all share remarkably similar ore mineralogy, host-rock characteristics and basin settings. We suggest that this discrepancy is due to the development of these two basins close to the bases of ~ 8000-km-long supermountain belts. The supermountain belts were instrumental in raising oxygen levels in Earth’s atmosphere, as well as providing a voluminous source of groundwater and a powerful and long-lived driver for the fluid-flow system. The elevated oxygen levels facilitated the diagenetic processes that converted copper-bearing labile minerals to amorphous iron-oxides and smectite and then in turn to hematite and illite. When oxidized brines flushed through the basin successions, the liberated copper was transported to units containing carbon-rich mudstone and the metals were deposited. For the Katangan Basin, development of the Transgondwanan supermountain belt along its margins between about 525 and 510 Ma explains the delay of several hundreds of millions of years between basin formation and mineralization in the Central African Copperbelt. In contrast, development of the Mid-Pangean supermountain belt formed penecontemporaneous with the Permian Basin explains the similarity in timing between basin formation and mineralization in the Kupferschiefer.

Genesis of the Samba Cu deposit of the Central African Copperbelt in Zambia: Constraints from geochemistry and geochronology

The Samba Cu deposit is located in pre-Katangan Supergroup basement metavolcanic rocks of the Central African Copperbelt in Zambia. To better understand the formation of the Cu deposit, we use geochronologic, geochemical, and S isotopic data obtained for the deposit’s host rocks and sulfide minerals. Laser ablation−inductively coupled plasma−mass spectrometric (LA-ICP-MS) dating of zircon from host rocks, including quartz-sericite schist and biotite-sericite-chlorite schist, yields ages of 1967 ± 17 Ma and 1960 ± 20 Ma, which are interpreted as the crystallization ages of the original volcanic rocks. Re-Os analyses of molybdenite intergrown with chalcopyrite constrain sulfide deposition to 548.1 ± 7.5 Ma and 524.1 ± 7.3 Ma, which correspond to the timing of the Cu mineralization. LA-ICP-MS U-Pb analyses of metamorphic rutile from the biotite-sericite-chlorite schist yield a U-Pb age of 508.3 ± 6.6 Ma, which is interpreted to represent the age of regional metamorphism. The new data suggest that the Cu mineralization at Samba was synchronous with the Lufilian orogeny.

Copper solvent extraction on the African Copperbelt: From historic origins to world-leading status

Approximately 20% of current world copper cathode output is produced using a hydrometallurgical process route, generally referred to as the leach-solvent extraction-electrowinning flowsheet. Since its commercialization in the late 1960s, steady improvements in the performance and efficiency of the solvent-extraction reagents and equipment, combined with significant developments in leaching and electrowinning, have made an ever-widening range of ore types amenable to this technology. Following successful implementation on all major continents, a large proportion of growth in recent years derives from the re-emergence of copper solvent extraction in the Central African Copperbelt. This review provides a brief history of the development and evolution of copper solvent extractants and mixer-settler contactors, and the significance of the Copperbelt region in achieving commercialization and acceptance of the technology. The opportunities and challenges presented by the abundant high-grade oxide ores of the Copperbelt are contrasted with the processing of solutions derived from the low-grade mixed oxide-sulfide ore bodies that are prevalent in other geological regions. The current status of hydrometallurgical copper production in the African Copperbelt, within a global context, and a medium-term outlook for the technology are discussed.

Constellations of practice in copper ingots from Zambia and northern Zimbabwe, cal. AD 500–1700

ABSTRACT Rectangular, fishtail and croisette copper ingots have been found in many locations in Central and southern Africa where excavated samples date to between the fifth and eighteenth centuries cal. AD. For more than fifty years, scholars have debated whether these ingots were all made in the Central African Copperbelt, where there are many finds of matching moulds, or if moulds found in Zimbabwe show that copies were produced locally. Lead isotopic and chemical analyses have recently confirmed that the Copperbelt supplied copper ingots to both southern Congo-Kinshasa and the Zimbabwe Plateau between the ninth and eighteenth centuries, but that one HXR ingot can tentatively be sourced to the Magondi Belt copper deposits in northern Zimbabwe. We expand this discussion here by linking ingot chemistry and isotopic provenance with distribution patterns and ingot morphologies. The combined evidence suggests that groups making Luangwa Tradition pottery were responsible for transporting HIH and HXR ingots, and the technological styles for making them, far to the south of the Copperbelt. These croisette ingots link constellations of practice in the Copperbelt and Zimbabwe, possibly through the movement of specialised traders and metalworkers. We identify some of the individuals buried at Ingombe Ilede and Chumnungwa as possible examples of these specialists.

Petrogenesis of the Katangan mafic rocks, Zambia: Insights from lithogeochemistry, large igneous province classification, and petrological modeling

The Neoproterozoic Katangan mafic rocks are composed of gabbro and basalt sills, dykes, and flows. They are characterized as a large igneous province distributed throughout the 450 km long and 600 km wide arcuate Central African Copperbelt (CACB), and are in southeastern Democratic Republic of Congo and northwestern Zambia. Understanding the petrogenesis of these mafic intrusive rocks is vital to assist future studies, as examples regarding their relation to the vast Cu and Co deposits in the Central African Copperbelt or consequences of Rodinia's break up. Lithogeochemical data suggest that these rocks were formed due to an extensional regime developed during the rifting stage of the CACB, which resulted in the upwelling of the asthenospheric mantle. Consequently, petrological modeling demonstrated how these rocks derived from primitive magmas and evolved chemically through fractional crystallization, assimilation, and magma mixing, generating a range of compositions with close chemical affinity. Based on this analysis, we have subdivided them into two main groups with distinct sources each further subdivided into two subgroups. A voluminous group with ocean island basalt (OIB) affinities is widespread throughout the basin and can be modeled as the product of crustal assimilation by a picritic magma, concomitant with fractional crystallization. Magma types of this group have interacted with upper crust to develop a characteristic high Th/Ti trace element character. A less common magma represents the product of interactions between a tholeiite with enriched mid-ocean ridge (E-MORB) affinity with metasomatized subduction zone-modified lithospheric mantle (SZLM) to generate an array of moderately to extremely potassic magmas, which we classify as shoshonitic to ultrapotassic.

Reconstructing the geological provenance and long-distance movement of rectangular, fishtail, and croisette copper ingots in Iron Age Zambia and Zimbabwe.

The southern third of Africa is unusually rich in copper ore deposits. These were exploited by precolonial populations to manufacture wound-wire bangles, other forms of jewelry, and large copper ingots that were used as stores of copper or as forms of prestige. Rectangular, fishtail, and croisette ingots dating between the 5th and 20th centuries CE have been found in many locations in the Democratic Republic of the Congo (DRC), Zambia, and Zimbabwe, with isolated finds in Malawi and Mozambique. Molds for casting these ingots have been found mostly in the Central African Copperbelt, but also around the Magondi Belt copper deposits in northern Zimbabwe. For years, scholars have debated whether these ingots were exclusively made in the Copperbelt or if the molds found in Zimbabwe indicate that local copies were produced from Magondi Belt copper ore (Garlake 1970; Bisson 1976). Before the recent application of lead isotopic and chemical methods to provenance copper in central and southern Africa, there was no way to discern between these hypotheses. Rademakers et al. (2019) and Stephens et al. (2020) showed that copper artifacts from southern DRC (mostly from Upemba) and from northwestern Botswana (Tsodilo Hills) match the lead isotope ratios of ores from the Copperbelt. Building upon these previous studies, we present here the first results from a copper provenance project across the southern third of Africa, from the Copperbelt to northern South Africa. We apply lead isotopic analysis (LIA) and chemical analyses to establish the provenance of 29 croisette ingots recovered in Zimbabwe, 2 fishtail and 1 rectangular ingot recovered from sites in Zambia, and an "X" shaped ingot smelted in an experiment in Zambia in the 1970's. Our chemistry and lead isotopic results indicate that 16 of these objects were smelted with copper from the Copperbelt, 16 objects source more specifically to the Kipushi deposit within this geological district, and only one HXR ingot sources to the Magondi Belt in Zimbabwe. Taken together, we clearly illustrate that croisette ingots were traveling significant distances to reach their eventual sites of deposition, and that there was also local production of these objects in Zimbabwe.

Textural and geochemical evidence for two-stage mineralisation at the Kamoa-Kakula Cu deposits, Central African Copperbelt

Textural and geochemical evidence for two-stage mineralisation at the Kamoa-Kakula Cu deposits, Central African Copperbelt

Living standards of copper mine labour in Chile and the Central African Copperbelt compared, 1920s to 1960s

ABSTRACT Large-scale copper mining has been the main industry in Chile and the countries conforming the Central African Copperbelt for about one century. While a relatively extensive social science literature exists on the mostly adverse macroeconomic and institutional effects of a high reliance on mineral exports and revenues, we address the effects on the labour force employed by this industry. We perform a novel inter-continental – as well as dynamic-historical – comparative assessment of the living standards of the domestic copper mineworkers in the three countries from ca1920 to ca1960. There are important similarities and disparities in levels and trends of real wages and other welfare provisions. In explaining the gap across continents, we discuss labour shortage and labour provision, productivity, and mobilization. We also highlight the underlying role of colonialism in determining the inter-continental differences. Copper miners are further found to have been better paid than other workers in all three countries.

3D structural and geological modeling of the Kwatebala Cu–Co deposit, Tenke-Fungurume district, Democratic Republic of Congo

The Kwatebala Cu–Co deposit is one of the giant deposits of the Central African Copperbelt and is part of the Tenke-Fungurume district, the world's largest known resource of cobalt, located in the Democratic Republic of Congo. The application of 3D implicit geological modeling in the Cu–Co Kwatebala deposit defined not only the lithological and ore models but also a complex structural framework. A total of six groups of faults were defined and suggest the occurrence of two tectonic events subdivided into five local stages in the Kwatebala Cu–Co deposit. The hierarchy of these stages was correlated to the tectonic evolution data in the literature showing initial thrusts defining the allochthonous position of the deposit in a pre-Lufilian stage. Salt tectonics-related moves in the early stages of Lufilian orogenesis, defining the Kwatebala diapiric structure. Posterior inverse faults of high angle and northward dip are probably related to the circulation of saline hydrothermal fluids responsible for a later Cu–Co synorogenic mineralization. Two later groups of faults displace the ore bodies, the first being related to thrust faults dipping south related to the end of the Lufilian arc evolution and finally the northwest faults that cut all the other previous structures.