Abstract The Zambian Copperbelt accounts for approximately 46 percent of the production and reserves of the Cen tral African Copperbelt, the largest and highest grade sediment-hosted stratiform copper province known on Earth. Deposits in the Zambian Copperbelt are hosted by the Neoproterozoic Katangan Supergroup, a rela tively thin (~5 km) basinal succession of predominantly marginal marine and terrestrial metasedimentary rocks that lacks significant volumes of igneous rocks. The stratigraphic architecture of the Katangan Supergroup in the Zambian Copperbelt is comparable to that of Phanerozoic rift systems. The basal portion of the sequence (Lower Roan Group) contains continental sandstones and conglomerates deposited in a series of restricted sub-basins controlled by extensional normal faults. These largely terrestrial sediments are abruptly overlain by a re gionally extensive, variably organic rich marginal marine siltstone/shale (Copperbelt Orebody Member, or “Ore Shale”) that contains the majority of ore deposits. This horizon is overlain by laterally extensive marine car bonates and finer grained clastic rocks that evolved through time into a platformal sequence of mixed carbon ate and clastic (Upper Roan Group) rocks with abundant evaporitic textures, including widespread breccias thought to record the former presence of salt, now dissolved. Rocks of the overlying Mwashia and Kundelungu groups are dominantly shallow marine in origin. Three significant tectonic events affected the basin. Extension associated with early rifting led to the devel opment of isolated fault-controlled basins and subsequent linkage of these basins along master faults at the time of Copperbelt Orebody Member deposition. A later period of extension occurred during late Mwashia to early Kundelungu time (~765–735 Ma) and is associated with limited mafic magmatism. Basin inversion and later compressive deformation (~595–490 Ma) culminated in upper greenschist-facies metamorphism (~530 Ma) in the Zambian Copperbelt. The majority of ore deposits in the Zambian Copperbelt occur within a 200-m stratigraphic interval centered on the rocks of the Copperbelt Orebody Member. Deposits are broadly stratiform and are grouped into argillite- (70% of ore) and arenite-hosted (30% of ore) types. The distribution, geometry , and size of deposits are fundamentally controlled by early subbasin fault architecture and the availability of both in situ and mobile reductants, the distribution of which is linked to basin structures. Argillite-hosted deposits occur within rela tively dark and locally carbonaceous siltstones and shales, suggesting the former presence of an in situ organic reductant. These deposits are laterally extensive with strike lengths up to 17 km. Arenite-hosted deposits occur in both the footwall and hanging wall of the Ore Shale and have maximum strike lengths of 5 km. They occur at sites that were geometrically favorable for mobile hydrocarbon or sour gas accumulation. Both argillite- and arenite-hosted deposits contain so-called barren gaps of weakly to unmineralized strata that are typically asso ciated with the fault-bounded shoulders of early subbasins. Two mineralization assemblages occur in the Zambian Copperbelt. The volumetrically dominant type con sists of prefolding disseminated and lesser vein-hosted Cu-Co sulfides. The most typical sulfide assemblage in the deposits is chalcopyrite-bornite with subsidiary chalcocite and pyrite. The Zambian Copperbelt is unusual among sediment-hosted stratiform copper districts in having abundant Co and low Ag, Zn, and Pb. The Cu-Co sulfide carrollite is widespread in the district, although cobalt is present in economic quantities in only some deposits on the western side of the district. The Zambian Copperbelt also contains ubiquitous, but volumetri cally minor, Cu-U-Mo-(Au) mineralization in postfolding veins. Cu-Co sulfides display complex textural relationships that are best explained by multistage ore formation. Diagenetic to late diagenetic mineralization is indicated by the typically nonfracture-controlled distribution of both sulfide and gangue phases, replacive textures of Cu-Co sulfides after diagenetic cements and pyrite, and an approximate 815 Ma Re-Os isochron age for sulfide precipitation at the Konkola deposit. Brines ca pable of mobilizing metals were most likely generated during development of evaporitic environments in units of the Upper Roan Group, and/or subsequent dissolution of these evaporites to form the Upper Roan Group breccias. Late diagenetic to early orogenic mineralization is recorded by prefolding bedding-parallel veinlets and tex turally and compositionally comparable disseminated Cu-Co sulfides. An Re-Os isochron age on Cu-Co sul fides from two arenite- and one argillite-hosted deposits of 576 ± 41 Ma is consistent with early orogenic hy drocarbon or sour gas production. The minor Cu-U-Mo-(Au) mineralization event occurred following postpeak metamorphism, at approximately 500 Ma. The Zambian Copperbelt ore province is characterized by stratigraphically and laterally widespread meta somatism that records a protracted history of basinal brine migration. Although the alteration history is com plex, it can be broadly categorized into an early Ca-Mg-SO 4 , anhydrite- and dolomite-dominant stage involv ing brine reflux below the level of Upper Roan Group evaporites; a second, K-dominant stage characterized by widespread and commonly intense development of K-feldspar and locally sericite, best developed in rocks of the Lower Roan Group and associated with ore; and a third, Na-dominant stage characterized by development of albite, commonly at the expense of earlier-formed K-feldspar. Albite dominates in Upper Roan Group brec cias and Mwashia-Lower Kundelungu strata. It is also locally associated with a late Cu-U-Mo-(Au) vein event. Although none of these alteration types are direct guides to ore, they demonstrate widespread brine circula tion within the lower parts of the Katangan Supergroup.

Abstract The Central African Copperbelt, including the Zambian Copperbelt, Congolese Copperbelt, and deposits in the North West Province of Zambia, is the world's largest and highest-grade sedimentary copper province, with approximately 200 Mt of contained copper and the world's largest cobalt reserves. It is hosted in Neoproterozoic metasedimentary rocks of the Katangan Supergroup (∼880 and ∼600 Ma) deposited in a series of intra-continental rift basins with abundant evaporite deposits. Early rift-stage continental rocks were overlain by a sequence of mixed evaporitic carbonate and clastic rocks, followed by a second period of renewed rift-stage clastic and mafic rocks. Widespread glacial and postglacial deposits covered this lower part of the basinal sequence, and mark an uppermost limit to the distribution of major copper deposits. Subsequent depositon of relatively monotonous, nonevaporitic basin fill clastic and lesser carbonate rocks preceded basin inversion during the Pan-African (∼590–500 Ma) Lufilian orogeny. The Copperbelt contains copper deposits in a range of rock units at a number of different stratigraphic levels. These deposits display differing styles and textures of mineralization and alteration types. Deposits may contain either or both disseminated, generally fine-grained sulfides and vein-hosted, generally coarse-grained sulfides. Nevertheless, there are shared characteristics among most deposits. Deposits are hosted at stratigraphic or structural redox boundaries. Where deposits occur in the stratigraphically lowermost reduced rocks, overlying reduced or favorable rocks generally were not mineralized. Although redox was a fundamental control for mineralization, the most carbonaceous rocks within an ore horizon are commonly not economically mineralized. Ore sulfide zonation within deposits occurs on multiple scales, with complexity of zoning broadly related to the complexity of the host-rock sequence. Macrostructural controls on deposit position suggest that extensional faults were important in controlling fluid flow, either directly or indirectly through influence on sedimentary and probably diagenetic facies variation. The stratigraphic section within which the deposits are located was affected by regional potassic, magnesian, silicic, and/or sodic alteration controlled partly by lithol-ogy and indicative of the passage of basinal brines. Mineralization in the Copperbelt appears to have occurred over a protracted period that spanned diagenesis, basin inversion, and metamorphism. This attests to the longevity of ore-forming brines resident within the Katangan basin and at least the upper part of its basement. The near-surface portions of deposits throughout the Central African Copperbelt have undergone oxidation and supergene enrichment and such enrichment has been important in upgrading the copper tenor of many deposits.

Abstract Zambia is a land-locked country occupying an area of 752 614 km 2 , with the geology dominated by Archaean to Neoproterozoic age rocks that contain significant mineral resources. Economically, the most important of these are the Neoproterozoic Katangan rocks, which yield the copper and cobalt ores exploited in the Zambian Copperbelt. Copper and Cobalt exports account for over 80% of Zambia’s foreign exchange earnings. Coal-bearing rocks of Karoo age (Permo-Carboniferous to Early Jurassic age) occur in rift valley basins such as the mid-Zambezi Valley in the south of the country. Issues such as a lack of capital investment led to privatization of the Zambian large-scale mining industry. Smaller scale gemstone mining is becoming increasingly important. For example, in 1998, the Ministry of Mines and Minerals Development granted over 200 gemstone-mining licences, 30 small-scale mining licences and prospecting permits, and over 70 artisanal mining rights for various minerals. A policy Framework Paper (1999–2001) published by the Zambian Government encourages the formalization of small-scale mining activities through the provision of licences for small-scale mining and gemstone trading, and the establishment of four regional mining bureaus for licensing and other services to the mining community. Furthermore, the Government has embarked on a Mining Sector Diversification Project with the support of the European Union, with the objectives of increasing export earnings through economic diversification, generating employment opportunities and contributing to poverty alleviation. In addition, the new policies and legal framework encourage private ownership of medium- and large-scale mining operations, and development of new mines. Currently, all former Government-owned mines that were under Zambia Consolidated Copper Mines Limited have been privatized. These activities are slowly generating much needed new investment to the mineral industry in Zambia. For many years, copper mining has supported the social and economic development of Zambia, accounting for around 90% of all Zambia’s foreign exchange earnings in 1991. Copper reserves are steadily declining, with total reserves remaining estimated at just over 2 billion tonnes at an average grade of 2.51% total copper. There are no recent economic mineral deposits discoveries to replace depleting copper reserves. Lead and zinc mining at Kabwe finished in 1994 due to reserve depletion. The Maamba Coal Mine in the Zambezi Valley is in need of re-equipment and modernization. Gemstone mining and marketing needs a complete overhaul. This paper reviews the major issues that have contributed to decline in sustainable development of the mineral industry in Zambia and highlights initiatives, both private and public, currently undertaken to revitalize the sector.

Abstract The integrated interpretation of aeromagnetic data is a key exploration tool to define the concealed, potentially prospective geology that we plan to explore. It helps define the district-scale morphology of structural networks and predict which structures may be associated with the formation of mineral deposits. Aeromagnetic data is particularly useful in guiding geologic mapping, exploration targeting, and strategy because the data available is usually broad, geologic processes and features are normally well imaged in the data, and it is relatively cheap to acquire and process. A foundation to the interpretation of the geophysical data is that the interpreter should be a geoscientist familiar with the geology of the area in question, maximizing the integration of geologic knowledge of the area into the interpretation product. The interpreter must think geologically when building the interpretation, drawing on the parallels between aeromagnetic interpretation and geologic mapping/air photo interpretation. Geologic mapping observations have direct parallels in aeromagnetic interpretation (e.g., lithology, structure, alteration). The interpretation process is outlined using the Lake Lefroy region, Western Australia, including form line construction, identification of magnetic rock units, domain definition, data set integration, definition of structural elements, lithological definition, interpretation of the structural framework, and evaluation of the interpretation. Case studies are then provided at a range of scales from the Pine Creek inlier in northern Australia, the Superior province in eastern Canada, and the Zambian Copperbelt Northwest province to illustrate the connection between the interpretations and exploration targeting. The final integrated interpretation is a supplement to outcrop maps, not a competitor. The purpose is to generate a structural and lithological framework that combines the geophysical data of different types with the mapped geology, which can be interrogated by mineralization models over a much wider area than can be achieved if structural elements and lithology are restricted to areas of outcrop.