Central African Copperbelt - Zambian Copperbelt


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Deposit Description

The Zambian Copperbelt is part of the larger Central African Copperbelt, and extends north into the neighbouring Democratic Republic of Congo (DRC), to continue as the Congolese Copperbelt. It closely coincides with a complex, arcuate structural zone, the Lufilian Arc, which trends from east-west in the west, to NW-SE to NNW-SSE in the SE. This arcuate structure is developed normal to, and near the northeastern extremity of the elongate, 2000 km long, NE-SW trending, Damaran-Katangan belt of Meso- to Neoproterozoic sedimentary rocks that extends across the continent to the Atlantic Ocean in the SW.

Regional Setting

The >500 km long Lufilian Arc is a structural element imposed upon the rocks of the Katanga fold belt in western Zambia and southern DRC during the ~590 to 510 Ma Lufilian Orogeny. It substantially reactivated and reflects earlier syn-depositional structures, and extends from the edge of the Archaean Congo/Kasai craton in the NW, to the major trans-continental WSW-ENE trending, sinistral, Mwembeshi Shear Zone to the SE, separating it from the Zambezi Belt to the south. The Zambezi Belt trends east-west, normal to the Lufilian Arc, and is a zone of shearing and metamorphism that rims the northeastern margins of the Kalahari craton to the south. Porada and Berhorst (2000) suggest the Mwembeshi Shear Zone marks a suture between the predecessors of the Kalahari and Angolan/Congo cratons that were welded during the Ubendian-Eburnian cycle in the Palaeoproterozoic, and has focussed subsequent tectonic activity from the Palaeo- to late Neoproterozoic.
   The Kalahari and Congo cratons are composites of earlier Archaean nuclei (e.g., the Kaapvaal and Zimbabwe cratons within the former) and Palaeo- to Mesoproterozoic elements that were amalgamated and cratonised by ~1.05 Ga as part of the Rodinia supercontinent.
   Magnetic data and deep drilling below cover, suggest the structural trend of the Lufilian Arc curves to the SW and south from its NW margin along the Congo Craton to the vicinity of the Mwembeshi Shear Zone in the SW in NW Botswana (Hitzman et al., 2012; De Wit, 2009)
   The oldest orogenic basement rocks between the cratons are exposed as inliers within, and marginal to the Lufilian Arc, particularly in the core of the Zambian Copperbelt and the Bangweulu Block to the NE. They dominantly comprise a Palaeoproterozoic, Eburnian-Ubendian (~2.05 to 1.82 Ga) calc-alkaline magmatic arc sequence of metasedimentary, metavolcanic and intrusive granitoid rocks of the Lufubu Metamorphic Complex (Rainaud et al., 2005; Selley et al., 2005). These rocks are interpreted to be part of a broader, regionally extensive, ENE-WSW Palaeoproterozoic magmatic arc terrane, paralleling the Mwembeshi Shear Zone, stretching from northern Namibia to northern Zambia, between the Kalahari and Angola/Congo craton, then swinging to the NNE-SSW to NNW-SSE, in northern Zambia and the DRC, where it separates the Congo and Tanzanian cratons (Rainaud et al., 2005; Porada and Berhorst, 2000; Petters, 1986). The Neoproterozoic Lufilian Arc straddles the confluence of these two structural trends. In the east and below the Katanga sequence, this basement includes a reworked Neoarchaean component (2.73 Ga; in the Bangweulu Block only), a Palaeoproterozoic granitic phase (2.05 to 1.93 Ga) and a Palaeoproterozoic plutono-volcanic magmatic arc complex (1.87 to 1.82 Ga; De Waele and Fitzsimons, 2007 and sources cited therein). This orogenic terrane is inferred to have been related to the Ubendian-Eburnian collision mentioned previoiusly, and was accreted onto the southern and eastern margins of the Congo Craton during the ~1.4 to 1.0 Kibaran orogeny, represented by a broad SW-NE trending string of 'Eburnian basement inliers' (Porada and Berhorst, 2000).
   To the south of the Zambezi belt, a partially coeval sequence of 2.16 to 2.10 Ga continental to shelf clastic and lesser carbonate sedimentary rocks, with a mafic volcanic component, the Magondi Supergroup, was deposited over the margins of the Archaean Zimbabwe craton (Master,1991). This sequence hosts the Magondi Copperbelt deposits in Zimbabwe, ~400 km south of the Zambian Copperbelt (see the separate Magondi Belt record).
   The Archaean to early Palaeoproterozoic basement rocks of the Congo and Kalahari craton are separated from the Neoproterozoic sequence of the Katanga Supergroup by the Mesoproterozoic Kibaran and Palaeo- to Mesoproterozoic Irumide successions respectively. These rocks represent the extensive, generally northeast-trending, Kibaran and Irumide mobile belts, which were precursor rift basins to the Neoproterozoic Katangan sequence, bifurcated and separated by the Bangweulu Block and Tanzanian Craton.
   The ENE-WSW elongated Irumide belt stretches over a distance of approximately 900 km from central Zambia to the Zambia-Tanzania border and northern Malawi, bounded to the NW by the Archaean to Palaeoproterozoic basement lithologies of the Bangweulu block, and truncated to the NE by Mesoproterozoic and Neoproterozoic transcurrent shear zones within reactivated parts of the Palaeoproterozoic Ubendian belt. To the SE and south, Irumide rocks were reworked within the Neoproterozoic Lufilian and Zambezi belts, and to the east by the Mozambique Belt.
   The Irumide sequence comprises a thick (>8 km) sequence of variously metamorphosed conglomerates, sandstones and shales with lesser dolerite flows, and thin overlying graphitic shales, evaporites, stromatolitic limestones and dolostones. It occurs as a condensed succession over the Bangweulu Block, passing into a thick marine sequence to the south. Metamorphic grades range from greenschist facies in the northwestern foreland overlying the Bangweulu Block, to upper amphibolite facies in the southeast, with local granulites (De Waele, 2004). Dating reported by De Waele (2004) and De Waele and Fitzsimons (2007) suggest the Irumide rocks were deposited in two episodes, the first, an extensive quartzite-metapelite succession with minor carbonate (Mporokoso, Kanona and Manshya River groups), deposited in the Palaeoproterozoic at ~1.8 Ga (from interlayered 1815 Ma volcanic rocks), and a second, more restricted sequence which consists largely of very mature, fluvial sandstones (Kasama Formation) at ~1.4 Ga that recycled sediments from the first episode rocks (De Waele, 2004). Peak metamorphism in the Irumide sequence was at 1.05 to 1.02 Ga (Rainaud et al., 2005). Voluminous syn- to post-kinematic Irumide granitoids were emplaced between 1.05 and 0.95 Ga. In addition, a minor suite of 1.36 to 1.33 Ga anorogenic plutons (nepheline syenite and biotite granite) have been identified in the far northeastern Irumide belt. Geochemical data indicate uniform crust-dominated patterns and the significant participation of older crust in the generation of all of these magmatic suites (De Waele, 2004).
   Within the Zambian Copperbelt, Lufubu Metamorphic Complex rocks are unconformably overlain by a supracrustal metasedimentary sequence of conglomerates, orthoquartzites and metapelites, the Muva Group that have been correlated with the Irumide sequence, but assumed to be ~1.3 to 1.05 Ga (Selley et al., 2005), but may be older.
   To the NW of the Katangan rocks, the >10 km thick, 1.4 to 1.05 Ga Kibaran sequence which is broadly coeval with the second Irumide pulse. It can be subdivided into four lithostratigraphic units (Laghmouch et al., 2012), from the base: i). Kiaora Group - dominantly phyllites and schists with quartzite horizons, and rhyolites at the top and intracontinental, rift related bimodal intrusions dates at between 1380 and 1370 Ma (Tack eta al, 2010); ii).  Nzilo group - predominantly quartzite, with local (quartzo-)phyllitic interbeds; iii). Mount Hakanssson Group - dark slates and quartzites, with basal conglomerates; iv). Lubudi Group - dark arkoses with conglomerate lenses, black graphitic shale, some sandstone, and an upper limestones and dolostone unit, often with silicified stromatolites.
   Two main styles of granitoid intrusion are recognised in the Kibaran Belt, syn- and post-orogenic phases at ~1.3 to 1.25 and 1.2 to 0.95 Ga respectively. The syn-orogenic gneissic to un-metamorphosed granitoids accompanied compression and basin inversion, while those of post-orogenic origin are alkaline and include the Kibaran tin granites (Petters, 1986 and sources quoted therein).
   The Neoproterozoic Katanga Supergroup of the Katanga fold belt separates, and laps onto, both the Kalahari and Congo Mesoproterozoic cratons of southern and central Africa respectively (which by now incorporated the Kibaran and Irumide belts). It is one of a number of similar Neoproterozoic Pan-African fold belt sequences (including the Damaran, Kaoko and West Congo) that fringe and/or separate these two cratons, and which may be interconnected below intervening Phanerozoic cover.
   In most of the Pan-African mobile belts of southern and central Africa, a ~200 m.y. period of tectonic quiescence followed the assembly of Rodinia, before extension and Neoproterozoic sedimentation heralded the commencement of its breakup. The exception may be the southern margin of the Damaran fold belt, where deposition may have continued from 1.1 Ga.

In the Zambian section of the Lufilian Arc, the resultant 4 to 10 km thick, Katanga Supergroup (~880 to ~530 Ma) comprises an initial sequence of coarse grained, fluvial conglomerates and sandstones, dominantly siliciclastics, devoid of volcanic activity, deposited within relatively restricted, fault controlled, NW-SE elongated intracontinental rift basins, occurring as horsts and half grabens. These rift basins were the result of NE-SW directed extension, parallel to the major regional Mwembeshi Shear Zone, and flanked a NW-SE trending basement high, now reflected by the younger Kafue Anticline.
   The Katanga Supergroup commences with the Mindola Clastics Formation, a variable sequence from 0 to 1300 m thick, most commonly up to ~150 to 240 m, composed of an oxidised suite of interbedded conglomerates, arenites, quartzites and lesser argillites. At the main deposits of the Zambian Copperbelt, it represents the footwall sequence, and contains basal conglomerate that varies from thin developments a few tens of metres, up to ~240 to 300 m thick, to near 1200 m on the northern margin of the Kafue Anticline, east of Konkola and Nchanga (although the latter may in part be due to structural repetition). This conglomerate is overlain by an arenite/quartzite unit, with rare argillites, and some conglomerate interbeds, particularly near the upper transitional contact, that similarly varies from a few tens of metres to as much as 300 m in thickness. These are followed by another conglomerate that is a few to a few tens of metres thick, then a further arenite/quartzite of similar thickness, and a final footwall conglomerate that is only a few metres thick. Locally at Nchanga, the upper two conglomerates and intervening arenite are absent. On the eastern margin of the Kafue Anticline, the Mindola Clastics Formation equivalent primarily comprises a 0 to 150 m thick sequence, commencing with a thin basal conglomerate, overlain by a succession of quartzite and grits.
   These depositional centres were subsequently linked along master faults, marking a transgression, reflected by the deposition of local finer facies of the Copperbelt Orebody Member, the basal unit of the Kitwe Formation. The Copperbelt Orebody Member (or "Ore Shale") represents the culmination of early rift-stage extension and the first marine incursion within the Katanga basin in the Zambian Copperbelt. It comprises coarse and fine siliciclastic sedimentary rocks, representing fluctuating emergent and subaqueous conditions. The unit varies from 0 to as much as 60 m, more commonly 15 to 35 m thick, and frequently commences with a basal band of dolomitic schist, representing a décollement. It comprises carbonaceous and/or dolomitic siltstones, argillites, thin dolostones and fine sandstones, and hosts the bulk of the ore in the main large deposits of the Zambian Copperbelt (e.g., Luanshya, Nkana, Mindola, Chambishi and Konkola), although a number of smaller deposits (e.g., Chibuluma, Fitula and Mimbula) are hosted by the Mindola Clastics Formation. To the east of the Kafue anticline (e.g., at Mufulira), the probable stratigraphically equivalent unit of the Copperbelt Orebody Member is the 1 to 2 m thick dolomitic bed known as the "Mudseam" (Binda, 1994).
   The remainder of the Kitwe Formation varies from <100 to >300 m in thickness, and at most localities commences with a quartzite to arkose unit, which may be locally absent (e.g., Nkana). It is followed by a finer unit that varies from argillite to dolomitic argillite or sandstone, to dolostone and dolomitic schist, that varies from a few to 160 m thick, culminating in a generally 10 to 30 m dolostone band. These are succeeded by a thick (up to 160 m) of feldspathic and dolomitic sandstones, interbedded with coarse grained calcareous sandstones to grit. At Nchanga, the ore extends upward into the sequence above the Copperbelt Orebody Member, with much of the ore within feldspathic quartzite of the "hanging wall", capped by a shale interbed.
   The Mindola Clastics and Kitwe Formations, together, comprise the Lower Roan Subgroup. The upper two units of the Kitwe Formation (dolostone and calcareous sandstones to grit) were included into the Upper Roan Subgroup by earlier authors (e.g., Mendelsohn, 1961), although the Lower to Upper Roan Subgroup boundary has been shifted to the base of the Upper Roan Dolomite unit in more recent papers (e.g., Binda and Mulgrew, 1974).
   Significant authigenic anhydrite is found in the Lower Roan Subgroup, in particular within the upper Mindola Clastics and lower Kitwe formations. Narrow evaporite units are also indicated by local breccias and porous units in both formations (e.g., within the Basal Quartzite at Nkana, and the Hanging wall Aquifer at Kirila Bombwe/Konkola).
   See the separate Luanshya, Mufulira, Nkana-Mindola, Chambishi, Nchanga-Chingola and Konkola-Lubambe records for the detailed stratigraphy through the Zambian Copperbelt.

The succeeding post-rift, thermal sag phase, produced the laterally more extensive platformal sequence of the Upper Roan Subgroup, comprising laterally extensive mixed shallow marine to lagoonal carbonate rocks and generally finer grained siliciclastic rocks with abundant evaporitic textures and mainly stratabound chaotic breccia (interpreted to represent the dissolution of evaporites). The sequence varies considerably in thickness, from <30 to 800 m, and is characterised by metre-scale, laterally extensive cycles of upward-fining, sandstone, siltstone, dolomite, algal dolomite and local anhydrite. Thickness variations can be abrupt and commonly are associated with breccias. The breccias are usually composed of rounded to angular, mm to metre sized polylithic intraformational clasts, set in a crystalline matrix of carbonate, albite, quartz, anhydrite and/or magnesian chlorite. The breccias may be single cm to metre thick bands, to stacked complexes, up to several hundred metres thick. In general they are stratabound, but on a larger scale, step down through the sequence to the south and west (Selley et al., 2005). The Upper Roan is alternatively known as the 'Bancroft' or 'Bancroft Kanwangungu' Formation by some authors (e.g., Cailteux et al., 2007), whilst an alternative amalgamation of the Upper Roan Subgroup to also include the carbonate and clastic units of the upper Kitwe Formation (the Kibalongo Formation of Cailteux et al., 2007), has been referred to as the Kirilabombwe Subgroup (e.g., Cailteux et al., 2007; Zientek et al., 2014).
   The Upper Roan Subgroup is interpreted to pass from mixed shallow marine and lagoonal evaporitic facies adjacent to the 'Kafue Anticline' and in the Congolese Copperbelt, to a deeper marine shelf environment to the west and SW (Porada and Berhorst, 2000), with lesser to no evaporites.

The Upper Roan Subgroup in Zambia is overlain across either a conformable transition, or an evaporite-facilitated breccia-detachment, by the 150 to 650 m thick Mwashya (or Mwashia) Subgroup, emplaced within a deepening marine setting. This sequence comprises a lower suite of reefal to intertidal clastic carbonate rocks, mainly arenitic dolostone with lesser argillaceous dolostone containing pseudomorph after anhydrite nodules, overlain by an upper succession of mainly carbonaceous shales, siltstones and lesser clastic carbonate rocks. The lower Mwashya is only poorly developed in Zambia, but in the DRC, the thicker equivalent, is included as the uppermost member of the Dipeta Subgroup, the Kansuki Formation (Cailteux et al., 2007). The Dipeta Subgroup is equivalent to the upper half of the Upper Roan Subgroup of Zambia (Cailteux et al., 2005; 2007; Hitzman et al., 2012). Mafic lava flows within Mwashya Subgroup equivalent rocks in NW Zambia are dated at ~765 Ma (Key et al., 2001), and are part of a regional suite of mafic rocks along the western margin of the Katangan basin, marking the onset of renewed extension.

second period of rift extension is reflected by the local intrusion of large ~765 to 736 Ma gabbroic sills in Zambia (commonly within the Upper Roan Subgroup dolostones) and equivalent pyroclastic and extrusive rocks within Kansuki Formation rocks of the equivalent upper Dipeta Subgroup in the northern part of the Arc in the DRC (and possibly some A-type granitoids). This extension commenced during the deposition of late Upper Roan Subgroup, and continued through into the Mwashya and lower Nguba groups (~765-735 Ma).

The base of the overlying Nguba Group (previously Lower Kundelungu) is defined by the 10 to 1300 m thick Grand Conglomérat, a regional sequence of debris flows, glacial diamictites, some mafic flows and numerous iron formations, correlated with the world wide ~740 Ma Sturtian glacial event. In the Zambian Copperbelt, the Grand Conglomérat occurs as a regionally extensive sequence of debris flows and diamictites, with minor thin intercalations of siltstone and sandstone, and varies from ~10 to 100 m in thickness. It is essentially a pebbly mudstone which shows erosional basal contacts, slump structures, fabric and correlatable pebble-size variations, indicative of a mode of deposition by mudflows. The pebbly mudstone is interbedded with, and passes laterally into finely-bedded argillites. Clasts include rare rounded basement clasts but is dominantly subangular fragments of rocks of the Mwashia and Upper Roan subgroups, indicating widespread glacial erosion of the middle part of the Katangan Supergroup.

Within Zambia, the Grand Conglomérat is overlain by a 400- to 500-m-thick, upward-deepening sequence of carbonates, dolomitic sandstones and siltstones and siltstones-mudstones, becoming progressively carbonate-poor and coarser to the north (Cailteux et al., 2007; Batumike et al., 2006, 2007). The lowest member is the massive carbonate rocks of the Kakontwe Limestone represented by 350 to 500 m of massive dolostones and limestones in Zambia, and by a thinner sequence of carbonate-bearing to carbonate-poor siltstones and sandstones northward into the DRC, and appear to represent shallow marine to fluvial sediments. The Kakontwe Limestone is best developed on the northern margin and over the domes of the Domes Region.

To the north, mostly in the DRC, this succession is overlain by the Kundelungu Group, the base of which is defined by the Petit Conglomérat, a glacial diamictite, believed to be the time-equivalent to the global ~635 Ma Marinoan glacial event (Hoffmann et al., 2004; Master and Wendorff, 2011). The Petit Conglomérat is overlain by a weakly metamorphosed and deformed sequence that passes upwards from limestones and dolomitic sandstones (the 'Calcaire Rose', capping the diamictite), through dolomitic siltstones and argillites, to sandstones with lesser carbonate rocks. This sequence is, in turn, overlain by the extensive, flat lying, continental clastic molasse succession of the Plateaux Subgroup, composed of argillaceous and arkosic sandstones, and conglomerates (Cailteux et al., 2005; Batumike et al., 2006, 2007).

South of the main Zambian Copperbelt, where the Domes Region intersects the basement Irumide Belt, structural trends are ~ESE-WSW, parallel to the Mwembeshi Shear Zone. In this area, surrounding and north of the Kabwe Zn-Pb deposit, the Katanga Supergroup unconformably overlies a Palaeo- to Mesoproterozoic basement complex largely made up of older Lufubu Metamorphic Complex rocks and younger Muva schist and quartzite, as well as mafic lavas of uncertain age. The lowest unit is a basal conglomerate, correlated with the Lower Roan Subgroup, overlain by the Kangomba Formation, a mixed unit of arkose, quartzite and conglomerate at the base, overlain by metasiltstone, schist and phyllite, capped by a dolostone (Moore, 1964; Cairney and Kerr, 1998). As discussed by Kamona and Friedrich (2007), the lower clastic and upper carbonate units of the Kangomba Formation have been correlated with the Lower and Upper Roan subgroups respectively. Kampunzu et al. (2009) regard the lower units as equivalent to the Lower Roan Kibalongo Formation (as defined above) and the remainder to the Upper Roan (Bancroft Formation).
  These are overlain by the Nyama Formation, a predominantly phyllite-dolomite unit with associated limestone-marble, which has been correlated with the Nguba Group (Moore, 1964; Intiomale, 1982), but it is also possibly equivalent to the Upper Roan Subgroup.
  Taylor (1954), Kortman (1972), and Intiomale (1982) recognised an Nguba Group equivalent lithostratigraphy at Kabwe, from the base, of: i). a matrix-supported conglomerate (Grand Conglomérat or Mwale Formation); ii). a finely bedded dolostone alternating with carbonate-rich and carbonaceous shales (the "Schistose Dolomite"); iii). a grey to dark grey bedded dolomite including lenticular carbonaceous shales ("Carbonaceous Dolomite" - which with the "Schistose Dolomite" are regarded as equivalents of the Kaponda Formation of the DRC); iv). light grey massive dolostone with frequent zones of recrystallised dolomite, locally fractured at the base (equivalent of the Kakontwe Limestone; Kampunzu et al., 2009).

The equivalent Katanga Supergroup sequence in the Zambezi Belt, to the south of the Mwembeshi Shear Zone where it hosts the Nampundwe Cu-pyrite deposit, includes a syn-rift, bimodal volcanic suite (the Nazingwe metabasalts and Kafue rhyolites) which yielded zircon ages of 879±19 Ma (Wardlaw, quoted in Hanson et al., 1994), and the associated Lusaka Granite (854±12 Ma; Barr et al., 1977). The Lusaka Granite is intrusive into basement, and tectonically overlain by Katanga Supergroup rocks. This magmatism is earlier than the commencement of sedimentation in the Lufilian Arc further north in Zambia where the broadly coeval ~880 Ma Nchanga Red Granite is separated by an erosional surface from the basal Katanga Supergroup. Within the Zambezi Belt, the Katangan Supergroup equivalents commences with the the Chunga Formation, composed of feldspathic quartzites, calcareous schists and dolomitic limestone, with the bimodal volcanic rocks at the base. The overlying Cheta Formation comprises a thick basal limestone, followed by quartz-muscovite (-chlorite) schist and quartzite. This is followed, in turn, by the Lusaka Dolomite, which ranges from dolostone to limestone and has been regarded as an equivalent of the Nyama Formation and Nguba Group, although it could also be part of the Upper Roan Subgroup (Barr et al., 1978; Kampunzu et al., 2009). The Kawenta Formation marks the top of the sequence, and is argillaceous at the base overlain by a psammitic facies. All of these rocks have been subjected to medium to high grade metamorphism (Petters, 1986), occurring as paragneiss and high grade schist and amphibolites after the mafic volcanic rocks, which are the Makuti-Rushinga, Malaputese and Kishira groups in Zimbabwe.
  The equivalents that lap onto the Archaean Zimbabwe craton to the south of the Zambezi Belt, are represented by limestone, dolomite and orthoquartzite of the Tengwe River Group, and the red grits, sandstones, shales and conglomerates of the Sijarira Group.

Tectonic, Tectono-stratigraphic and Structural Setting

The main (late-Katangan) Lufilian Orogenesis appears to span a period of >100 m.y., with the oldest metamorphic ages of ~590 Ma, the main stage orogenesis from 560 to 530 Ma and widespread dates of 510 to 465 Ma possibly recording post-orogenic cooling (Selley et al., 2005, and sources cited therein). The Lufilian event culminated in peak greenschist-grade metamorphism at ~530 Ma. This orogenesis was the result of compressive basin inversion, which occurred throughout the Katangan and Damaran systems from southern DRC to the Atlantic Ocean. The late-tectonic composite Hook Granite, which cuts the Nguba Group, comprises an older, magnetically flat set of medium-grained biotite-hornblende granitoid intrusions, dated at 559±18 and 566±5 Ma in two samples. These are cut by numerous, younger microcline-biotite-hornblende megacrystic phases, reflected by donut-shaped magnetic anomalies with diameters of from <10 to 50 km, interpreted to represent anorogenic ring complex intrusions. Samples of these intrusions have been dated at 533±3 Ma (Hanson et al., 1993; Nisbet et al., 2000; Lobo-Guerrero, 2010).
Location The Lufilian Arc comprises four distinct, north-convex, arcuate tectonic subdivisions, the:
i). External Fold and Thrust Belt to the northeast, mainly in the DRC (where it hosts the Congolese Copperbelt), characterised by thin-skinned thrust/nappe-dominated deformation, absence of exposed basement, low-grade metamorphism and structural repetition of the Katangan stratigraphy;
ii). Domes Region, which includes the Zambian Copperbelt in its outer margins, comprises a series of exposed basement domes, characterised by upper-greenschist facies metamorphism in the east, increasing in intensity to upper-amphibolite in the west.
  The belt is also characterised by a corridor of gabbroic intrusions, cutting both the basement in the domes, Upper Roan Subgroup and Nguba Group country rocks.
  The individual domes west of the Kafue Anticline, coincide with magnetic highs within a well defined arcuate belt of greater magnetic relief than the neighbouring Synclinorial Belt.
  Unconformable relationships between Katanga Supergroup rocks and older basement are preserved on the flanks of the Kafue Anticline, where upright to inclined, high-amplitude folds dominate. However, tectonic decoupling has been described at the same contact with basement domes further west, which are cored by recumbent folds and nappes, and juxtaposed thrust sheets of contrasting metamorphic grade (Cosi et al., 1992; Binda and Porada, 1995; Key et al., 2001).
  Daly et al. (1984) interpret the basement inliers in the Domes region to represent antiformal stacks above mid- to lower crustal ramps.
  These domes resemble metamorphic core complexes, capped by domal, radially outward-dipping detachments/décollements. The rocks above the décollements are usually metamorphosed to greenschist facies and comprise Katanga Supergroup lithologies, while those below are strongly metamorphosed Palaeo- and Mesoproterozoic gneisses and schists, with interpreted interleaved metamorphosed Neoproterozoic slices, and include quartz-feldspar-biotite±magnetite gneisses, garnet-bearing granite gneisses, etc., with a strong mylonite texture in the upper parts of the dome (cf., at Lumwana in the Mwonbezhi Dome). Talc-kyanite white-schists occur within the décollements between the basement and the Katanga Supergroup sedimentary sequence in the Domes (Hitzman et al., 2012), dated at ~530 Ma (John et al., 2004). Talc-kyanite white schists may be taken to represent ultra-high pressure, but low to moderate temperature metamorphism (e.g., John 2004), associated with subduction, collision and overriding of the Congo and Kalahari Craton. However, Hitzman et al. note that their occurrence in basement within hundreds of metres of overlying greenschist facies Katanga Supergroup rocks, suggests structural complexity and/or mobility of aluminium and unusual mineral growth during high-salinity, Mg-rich metasomatism. In addition, the white schists are localised, restricted to the margins of the domes and do not persist deeper, which would be expected in the John (2004) interpretation. White schists are interpreted to have formed elsewhere from granitic or sedimentary (sometimes evaporitic) protoliths by syn-metamorphic oxidation and Mg-metasomatism (e.g., Mautia Hill, Tanzania; Jons and Schenk, 2004).
  While the domes may represent extensional metamorphic core complexes formed during the renewed extension phase, they have been substantially modified, deformed and metamorphosed during the later compressive Lufilian Orogeny. The variations in metamorphic grade, shape and size, imply that, if they are metamorphic core complexes, they have been more deeply exhumed, and/or represent more deeply derived and uplifted core rocks to the west.
  The arcuate chain of domes described above, coalesce with the southern half of the more extensive Kafue Anticline on the southeastern margin of this region. The Kafue Anticline was a basement high during deposition of the Katanga Supergroup, although it also shares some of the extensional and subsequent compressional features seen in the domes to the west, and is locally fringed by décollement structures (e.g., in the Nchanga-Mindola district);
iii). Synclinorial Belt, where sedimentary rocks were subjected to large scale folding during at least two deformation events, and low grade metamorphism and is reflected by a more subdued pattern in magnetic data, contrasting with its neighbouring regions. It has been suggested this sequence, reflects a change from a marginal shelf in the north in what is now the External Fold and Thrust Belt, to a deeper basin SW of the Domes region (Cosi et al., 1992; Porada and Berhorst, 2000). However, Selley et al. (2005) suggested that they could find no evidence for a deeper marine sequence in the Synclinorial Belt; and
iv). Katanga Core (or Katanga High) to the southwest, in which only the upper parts of the Katanga Supergroup and almost all of the outcropping granitic intrusions of the Lufilian Arc are exposed (Petters, 1986; Selley et al., 2005). It is reflected by a more complex and variable pattern in aeromagnetic data, with a well defined margin.
  The Katanga High was first proposed by De Swardt and Drysdall (1964), who considered that it represented a central core of uplift (for unknown reasons), which induced gravitational sliding of the Katangan cover sequence to both the north and the south. To the NE, Roan (Nguba) and Kundelungu group rocks were folded, imbricated and thrust northwards to form the Lufilian Arc. As a mirror image, the Zambezi Belt developed from similar processes to the SW, with late-stage transcurrent movements on the Mwembeshi Shear Zone juxtaposing low-grade rocks of the Lufilian Belt and high-grade rocks of the Zambezi Belt. Porada (1989) and Porada and Berhorst (2000) argued against this interpretation, and suggested instead, the Katanga High was composed of late Katangan rocks over shallow basement, over-thrust to the NE onto the Synclinorial Belt during the Lufilian orogeny.
  The exact nature of the Katanga High remains unclear. Hitzman et al. (2012) do not differentiate it from the core of the broader Katangan basin. It may well occupy the central core of a wide, NE-SW elongated, shallow basin of marine-shelf facies rocks that extended from the Kasai/Congo craton in the NW, to south of the Mwembeshi Shear Zone to the Kalahari Craton to the SE, and from the Foreland and Bangweulu Block to the NE, into Angola, Namibia and Botswana to the SW. The current geophysical expression of the Katanga High may be no more than a reflection of the superimposed late-Lufilian magmatic event intrusions represented by the late-tectonic composite Hook Granite complex.

The northeastern margin of the Lufilian Arc is represented by exposures of the relatively undeformed upper units of the Upper Kundelungu Group within the Kundelungu Gulf Foreland. The eastern margin of the arc, to the east of the Zambian Copperbelt, passes into a similar prong of Nguba Group overlying Irumide rocks, separated from the Kundelungu Gulf by the triangular Bangweulu Block. This embayment represents transgression onto Irumide basement during the renewed extension that accompanied the onset of Nguba group deposition. The southern limit is defined by the major, WSW-ENE trending, sinistral Mwembeshi Shear Zone which separates it from the Zambezi Belt.

Following the two extensional events and deposition of the majority of the Katanga Supergroup, Late Neoproterozoic to Lower Cambrian basin inversion was initiated. Kinematics suggest NW to NE directed thrusting during this orogenesis, with displacement vectors radiating perpendicular to the arcuate trend of the fold belt (Selley et al., 2005). However, Porada and Berhorst (2000) and Kampunzu and Cailteux (1999) suggest the arcuate shape is the result of oblique compression during this event, between the northern margin of the Kalahari craton and the southwestern edge of the Congo craton. The stress field was complicated by the east-west compression that formed the major Mozambique Belt collision zone to the east, and resultant sinistral movement on the Mwembeshi Shear Zone, to produce 'oroclinal bending' and form the Lufilian Arc.

  See the Congolese/Katangan Copperbelt record for a more detailed summary of the deformation stages that formed the Lufilian Arc.

In Zambia, these phases of deformation are expressed as follows:

• Early Extension, which followed an ~100 to 200 Ma period of quiescence after the amalgamation of the Rodinia Supercontinent, and marks the early onset of its break-up.
   Within Zambia, this extension was directed NE-SW, parallel to the Mwembeshi Shear Zone, forming a series of fault controlled, NW-SE elongated basins. These basins were developed towards the SW limit of the thicker sequences within the precursor Kibaran and Irumide rift basins, which were thickest and widest to the NE, and thinned towards the region in which the Katanga Supergroup was subsequently deposited.
  This extension was heralded by bimodal magmatism south of the Mwembeshi Shear Zone (and the Lufilian Arc), in the Zambezi Belt, commencing with basal bimodal rift volcanic rocks (Nazingwe metabasalts and Kafue rhyolites) which yielded zircon ages of 879±19 Ma (Wardlaw, quoted in Hanson et al., 1994) and the limited Lusaka Granite (854±12 Ma; Barr et al., 1978) which is intrusive into basement, and tectonically overlain by Katanga Supergroup rocks. These volcanic units are interbedded with sedimentary sequences in the Zambezi Belt. Just to the north of the Mwembeshi Shear Zone, in the Kabwe area, mafic lavas of uncertain age which overlie the Irumide sequence may be related to this phase. Within the main Lufilian Arc, the coeval Nchanga Red Granite (877±11 Ma; U-Pb SHRIMP zircon; Rainaud et al., 2000) is overlain by the basal Katanga Supergroup above an erosional contact, without any volcanic component. Similar granites have been dated in basement near Lumwana (Barrick, 2014) in the western Domes Region, whilst similar granites in basement below the Mindola Clastics formation at Nkana-Mindola are suspected to be of this age also (Croaker, 2011). Unlike the equivalent magmatism in the Zambesi Belt, where volcanic rocks are interbeded with basal Katangan sedimentary rocks, these granites, have been uplifted, exposed and partially eroded prior to the first Katangan deposition. This suggests that during early extension intrusion of these granites accompanied uplift of the structural high that occupied what was to become the core of the Kafue Anticline (see below).
   To the north of the Lufilian Arc, the 813±30 Ma Gagwe Amygdaloidal Lavas, are deposited on the western flanks of the Tanzanian Craton, overlying Kibaran basement.
  The initial deposition of the Katanga Supergroup within the Lufilian Arc, was in narrow grabens, represented by the Lower Roan Subgroup Mindola Clastics Formation, which became interconnected and with further subsidence, grew into the larger rift basin that hosts the overlying Kitwe Formation and then the sag phase Upper Roan Subgroup.
  During this phase, the NNW-SSE trending structural high that was to become the core of the Kafue Anticline, influenced the distribution and thickness of facies. This structure also included the basement exposed in the Konkola and Luina domes, now separated by D1 and D3 synforms. It was partially emergent during deposition of the Mindola Clastics Formation, which on the rims of, and in remnant structural basins (e.g., Luanshya basin) in the core of the "anticline", contain basal conglomerates, channel sediments incised into basement, and aeolian sandstones.
  The same basement high was largely submerged during the deposition of the overlying Kitwe Formation, which grades from arenites over the crest of the basement high in the east, to a well defined shale corridor, before passing into deeper water turbiditic sedimentary rocks in the Synclinorial Zone to the west. Similarly, the structure is subsequently largely submerged, overlain by the shelf/carbonate-rich to lagoonal Upper Roan subgroup sequence (Porada and Berhorst, 2000);
  Breccias, interpreted to be after mobilised evaporitic units, are found within the Upper Roan subgroup over and adjacent to the Kafue Anticline. These breccias and interpreted evaporitic layers are much less developed than in the similar lithologies and halokinetic megabreccias of the mineralised sequence in the DRC.
Roan cross section • Renewed Extension, from ~765 to 735 Ma (Hitzman et al., 2012), accompanying, and post-dating deposition of the Mwashya subgroup and Nguba Group. During this period, the main centre of deposition migrated north from the region principally to the west of the "Kafue Anticline" basement ridge in Zambia, to be located in Katanga in the DRC, between the Domes Region and the Kundelungu Gulf Foreland (see Congolese/Katangan Copperbelt record for more detail).
  It is suggested here, that during this event, extension resulted in the development of a corridor of metamorphic core complexes in the Domes Region, including the Kabompo Mwonbezhi, Solwezi, Luswishi Dome and Kabuche domes, but not the Kafue Anticline (and subsidiary Luina and Konkola domes), which had formed as a faulted basement high during or prior to the Early extension. It is suggested that uplift associated with these metamorphic core complex domes, and the coeval deepening of the rift basin to the north, initiated northward verging gravity gliding of the evaporite-rich Upper Roan Subgroup over a décollement, which followed the interpreted salt/evaporite bed of the R.A.T./Upper Roan Subgroup. This produced a modified 'intraformational' package, comprising an imbricated stack of folded north-vergent thrust sheets and a zone of diapiric thickening in the mid External Fold and Thrust Belt (see the schematic section in the separate Congolese/Katangan Copperbelt record). This package, largely composed of megabreccia in the NE, represents extension and thinning of this unit in the Domes Region of northern Zambia, and shortening and thickening in the External Fold and Thrust Belt of the DRC. The upper limit of this deformed package would appear to be the breccia zone within the upper Dipeta Subgroup in DRC, below the poorly deformed Mwashya Subgroup.
  Both the Mwashya subgroup and Nguba Group are found over and flanking the Kafue Anticline and associated Konkola and Luina domes, the Solwezi dome and the External Fold and Thrust Belt. The dominantly shale facies of the Mwashya subgroup are best developed in the deeper section of the rift basin in the External Fold and Thrust Belt in the DRC, grading into sandy facies on the margin with the Kundelungu Gulf Foreland to the north, and to the SW towards the Domes Region (Cailteux et al., 2007). At the same time, deposition extended to the NW and SE over the marginal Kibaran and Irumide basement respectively, and into the Kundelungu Gulf Foreland. The Mwashya subgroup is absent or only present as thin oxidised conglomerate-sandstone wedges in these transgressive sequences, and is not mapped around the westernmost domes or to the SW of the domes, in the Synclinorial Belt or the Katanga Core, although they may have not been differentiated in these areas. The Nguba Group however, is well developed over most of these same intervals, although it appears to thin over the domes to the west of the Kafue Anticline, while the best development of the Nguba Group Kakontwe Limestone flank these domes, suggesting they were emergent or shallow during Nguba deposition.
  A ~30 to 100 km wide by ~500 km long, arcuate ESE-WNW trending corridor of gabbroic to dioritic intrusions follows the Domes region from the Luanshya Structural Basin through the Chambishi Structural Basin, Kabuche Dome, southern margin of the Nkana Dome, the Luswishi, Solwezi, Mwombezhi and Kabompo domes. These rocks vary from mafic to ultramafic in composition, mainly amphibolites, ophitic gabbros and olivine gabbros, but also basaltic lavas, norites, picrites, peridotites, Iherzolites, troctolites and a few eclogites and serpentinites. They are often lensoid and discontinuous, with structural margins accompanied by brecciation (Porada and Berhorst, 2000), although large masses up to 10 km across have also been mapped. Based on limited dating, and stratigraphic relationships, these intrusions are interpreted to be associated with the ~765 to ~735 Ma extensional event, and coeval with the mafic to intermediate volcanic rocks in the Dipeta and Mwashia subgroups and lower Nguba group in the DRC. They intrude rocks from the basement Lufubu Metamorphic Complex to the Nguba Group, and are frequently well developed in Upper Roan Subgroup carbonate rocks. Key et al. (2001) have mapped a belt of~765 Ma mafic lava flows along the western margin of the Katanga Basin in NW Zambia within the western margin of this corridor of mafic intrusions.
  The geochemical evolution of these mafic rocks ranges from earliest continental tholeiite to alkaline and tholeiitic magmas, and finally in the DRC, to lavas with E-MORB affinities, suggesting a progression from continental to a possible embryonic oceanic rift (Kampunza et al., 2000). Stratigraphic relationships at Kansanshi suggest some of these intrusions may be late Lufilian, <600 Ma in age. These mafic rocks are observed to have a wide variation in metamorphic overprint (Porada and Berhorst, 2000), which may be explained by their presence within and outside of the metamorphic core complexes of the Domes and two different ages.

• Main Stage Lufilian Orogenesis, commencing at ~590 Ma, but spread over the interval from 600 to 512 Ma (Armstrong et al., 2005), corresponding to the D1 Kolwezian tectonic event of François (1974) and Kampunzu and Cailteux (1999). The earliest greenschist facies metamorphism has been dated at 592±22 Ma (U-Pb monazite) and 585±0.8 Ma (Ar-Ar biotite; Rainaud et al., 2002), with peak metamorphism at ~530 Ma for talc-kyanite white schist metamorphism (John et al., 2004) in the thrust mylonites that cap the domes of the western Domes region.
  This, generally NE vergent compressional stage, corresponds to the structural inversion of the Katangan rift basin, and is characterised by complex polyphase deformation and superimposed thrust terranes, curved folds and sinistral strike-slip shear/fault zones.
  Décollements related to the earlier extensional phases appear to have been reactivated in the domes to the west of the Kafue Anticline, and rocks of the Mwashia and Nguba groups have been isoclinally, folded immediately to the NE of the domes, as interpreted at the Kansanshi deposit (see the separate Kansanshi record and the schematic section in the separate Congolese/Katangan Copperbelt record).
  The structure over and adjacent to the Kafue Anticline is characterised by thrusting within the basement, passing up to be expressed as folding within the overlying Roan Group rocks. This is evident across the anticline from Chingola-Nchanga eastward to Mufulira. In the west of this section, ENE verging thrusts follow the basement-Roan Group contact, passing upwards to emplace imbricated and interleaved wedges of basement gneiss and granite into Roan Group rocks. Further east, the basement thrust climbs into the Roan Group, and follows the Copperbelt Orebody Member of the basal Kitwe Formation as a décollement. This structure separates basement, granite and overlying Mindola Clastics Formation siliciclastic rocks, all of which are poorly folded, from overlying, strongly deformed, Kitwe Formation lithologies. Similar décollements and decoupling are common at this stratigraphic position elsewhere, e.g., at the Luanshya, Nkana and Chambishi deposits, exploiting the more fissile lithologies of the Copperbelt Orebody Member. Eastward, towards the centre and eastern margin of the Kafue Anticline, WSW facing folds and east dipping reverse faulting, thrusting and banded mylonite zones are evident. On the eastern margin of the Kafue Anticline, at Mufulira, ENE verging folds are evident although, these face downwards. Similar structures are mapped elsewhere on the same margin (Daly et al., 1984).
  Daly et al. (1984) interpret this structural pattern to reflect ENE vergent thrusting above a deep décollement within the basement of the Kafue Anticline, with associated branching subsidiary thrusts that climbed up through the sequence. The back thrusts to the east are interpreted to be compensatory structures, while the downward facing folds are taken to be equivalents of the structures on the western flank that have been subsequently tilted as the Kafue Anticline rose as a thrust culmination.
  The Kafue Anticline is also characterised by a series of basinal and domal structures e.g., the Luanshya and Chambishi structural basins, the Konkola and Luina domes and the basin between the Luina, Konkola domes and northern Kafue Anticline. These structures appear to be the result of interference between an earlier NE-SW and a later NNE-SSW compressional event. It is suggested that during the three separate pulses recognised by Croaker (2011), the direction of compression may have rotated to produce this interference pattern. Croaker (2011) also suggests the pattern of folding may be partly influenced by the orientation of the original rift/graben depositional basins and inhomogeneity of facies distribution, consistent with Annels (1984) who proposed the interference pattern is due to the overprinting of initial ESE-WNW trending rift phase depositional basins and the NE-SW compression.
  A D2 tectonic event is recognised in the northern sections of the Congolese Copperbelt (the Monwezian event of François, 1974, and Kampunzu and Cailteux, 1999), comprising a series of generally WSW-ENE to east-west sinistral, branching, strike slip faults displacing D1 Kolwezian structures. To the east and SE these structures curve to parallel the trend of the Lufilian Arc and trend SE. No equivalent structural phase is recognised in the literature in Zambia, other than the major WSW-ENE trending sinistral Mwembeshi Shear Zone to the south which truncates the Lufilian Arc and separates it from the Zambezi Belt. Possibly the set of WNW-ESE trending structures which offset the D1 folds of the Kafue Anticline area may be related to this event.
Cross section
• Late Orogenic Extensional Collapse, a brittle event, only recorded in the Lufilian Arc, which Kipata (2013) regards as probably post ~530 Ma. It caused NW-SE directed extension across the whole arc, and reactivation of earlier compressional and strike-slip structures. Selley et al. (2005) suggest the widespread 510 to 465 Ma Ar-Ar biotite and Rb-Sr muscovite ages (Cosi et al., 1992; Torrealday et al. 2000; Rainaud et al., 2002; John et al., 2004), most likely record post-orogenic cooling.

• Post-orogenic Transpressional Inversion, a NW-SE brittle transpressional inversion recorded in the Lufilian Arc also affects the Kundelungu Foreland and the fringing Irumide and Ubendian basement. It corresponds to the Lufilian D3 Chilatembo stage of Kampunzu and Cailteux (1999) and took place after the Lufilian extensional collapse. François (1993) suggested an age of ~305 Ma for this event, which Kipata (2013) similarly regards to be post-Lufilian, "most likely Palaeozoic in age". It produced large, gentle, open, upright folds with axes varying from NNE-SSW to ENE-WSW (e.g., the ENE-WSW oriented syncline that separates the Luina and Konkola domes from the main Kafue anticline), and north-south and east-west faults, low-angle thrusting of Nguba and Kundelungu group units, possibly accompanied by late salt diapirism in the DRC (Kampunzu and Cailteux, 1999; Schuh et al., 2012; Kipata, 2013). This phase is responsible for much of the interference folding seen in the DRC and northern Zambian sections of the Lufilian Arc.

• Uplift, Peneplanation and Cratonisation, followed by more recent extension related to the Cenozoic African Rift.

Zambian Copperbelt

Distribution of Mineralisation

Traditionally, the ore deposits of the Zambian Copperbelt have been interpreted to lie within the Neoproterozoic Lower Roan Subgroup, composed principally of coarse siliciclastics (conglomerate to arkose and siltstone, with lesser carbonate rocks). The main deposits define two NW-SE trending parallel lines of Cu mineralisation some 20 km apart, separated by the Palaeoproterozoic basement gneisses, granitoids and schists, and Mesoproterozoic conglomerates, quartzites and granitoids that make up the Kafue Anticline, in the eastern Domes Region of the Lufilian Arc. Each of these two belts is 5 to 20 km wide and up to 150 km long. Ore grade mineralisation, however, tends to occupy linear, often more structurally complex, semicontinuous bands, up to 2 to 3 km wide, and as much as 17 km long, particularly on the SW line, interrupted by narrow barren gaps and cross folded anticlinal basement ridges (e.g., the Nkana-Mindola, Nchanga and Konkola strings of deposits separated by barren gaps which coincide with basement hills and reef facies dolostones). The majority of the deposits are on the SW of the two lines of mineralisation, which coincides with a corridor of shale facies developed at the base of the Kitwe Formation, and lapping onto basement to the east.
   Within these two belts of deposits, there are some 6 major and >25 minor stratabound deposits. The major deposits are Luanshya-Baluba, Mufulira, Nkana-Mindola, Nchanga-Chingola, Chambishi and Konkola-Lubambe. The larger orebodies had production + resources that range from 90 to 1000 Mt @ 2.4 to 3.6% Cu. Between 1930 and 1987 some 24 Mt of copper metal was produced from 1.07 Gt of ore averaging 2.71% Cu. The total mined ore plus reserves/resources has been calculated at 3.28 Gt @ 2.68% Cu containing ~88 Mt of Cu (Selley et al., 2005 and references cited therein).

The Lower Roan Subgroup is conformably overlain by Neoproterozoic carbonate rocks of the Upper Roan Subgroup which is equivalent to the R.A.T., Mines and Dipeta subgroups in the External Fold and Thrust Belt of the neighbouring Democratic Republic of Congo (DRC). These rocks are mostly barren in the Zambian Copperbelt, but host most of the significant Cu-Co deposits of the Katangan section of the Central African Copperbelt in the DRC.

More recently, the Lumwana and Kansanshi operations, located in the central to western Domes Region to the west of the established Copperbelt, were brought into production. In 2013 they were the biggest copper producers in Africa, each with large, lower graded resources of 800 to 1000 Mt @ 0.5 to 0.7% Cu. These deposits have differences in the apparent mode of occurrence compared to the main copperbelt deposits fringing the Kafue Anticline. See the two overlapping images below for a geological summary of the Domes Regions and distribution of units described above. For more details of the local geology and the mineralisation styles, see the records for the Lumwana (Chimiwungo and Malundwe), Kansanshi, Enterprise and Sentinel deposits. Eastern Domes Region Western Domes Region


Mineralisation within the major deposits 'flanking' and overlying the Kafue Anticline has the following characteristics:

Fault Controls
   The geometry, size and distribution of orebodies is closely linked to early fault-controlled sub-basin architecture during deposition of the Lower Roan Subgroup. Basement faulting affected facies distribution on basement margins, the formation of structural and stratigraphic culminations influencing fluid flow and entrapment, and may also have provided pathways for fluid ingress, e.g., most argillite hosted orebodies overlie anomalously condensed wedges of Mindola Clastics Formation, where the overlying Copperbelt Orebody Member is transgressive onto basement, coincident with fault related trough margins/basement highs. Many orebodies are also located at the intersection of basin bounding faults. In addition, footwall and hanging wall arenite hosted orebodies are also frequently aligned along basin margin faults (Selley et al., 2005 and references cited therein).
   Many of the early basin controlling faults appear to have been reactivated during Mwashya to lower Nguba extension, reflected by changes in stratal thickness of Roan Group rocks and by increased folding and deformation that was commonly focused by these structures during Lufilian deformation (Hitzman et al., 2012).

Mafic magmatism
   Many of the largest deposits in the Central African Copperbelt, have a spatial association with mafic magmatism, e.g., Kamoa and Kolwezi in the DRC and Konkola and Kansanshi in Zambia, which are spatially associated with abundant mafic sills or flows or aeromagnetic anomalies that may represent buried mafic intrusions (M. Hitzman, unpub. data, 2010). The line of deposits of the Domes Region in Zambia (Sentinel, Enterprise, Lumwana and Kansanshi) fall within and are aligned along the major corridor of gabbroic intrusions that occupy that structural feature. In addition, the same gabbroic corridor obliquely intersects the Kafue Anticline from Luanshya in the south to Nchanga in the north, although mafic dykes are also found at Konkola. The flanks of the Kafue Anticline over this interval hosts virtually all of the large Cu-Co deposits of the Zambian Copperbelt. The corridor of mafic magmatism in the Domes/Kafue Anticline region of Zambia is dated at ~753 and 742 Ma (from 2 datings), while a belt of mafic intrusions and extrusions in the western Congolese Copperbelt was emplaced from 765 to 735 Ma.

Stratigraphic Control
   Copper ±Co ±Ni ±Au ±Ag ±U mineralisation within the Central African Copperbelt, emplaced after the commencement of deposition of the Katanga Supergroup at <580 Ma, to the end of the late Lufilian Orogenic cycle, is found in rocks from the basement Lufubu Metamorphic Complex (e.g., Samba) to ~510 Ma (e.g., Kansanshi).
   Stratabound mineralisation is restricted to host rocks from the "Footwall" orebodies in the Mindola Clastics Formation (Lower Roan Subgroup), to the Grand Conglomérat of the basal Nguba Group. Mineralisation in rocks older and younger are predominantly transgressive vein style, although they may include substantial amounts of bedding plane replacement outwards from mineralised vein margins.
   Significant Cu-Co, or Cu-Au or Cu-Ag ore deposits, are found in association with the following units within the Central African Copperbelt, including those that only host ore in the DRC:
• A package of rocks, up to ~150 m thick, straddling the Copperbelt Orebody Member, incorporating sections of the upper Mindola Clastics and lower Kitwe formations of the Lower Roan Subgroup. The Copperbelt Orebody Member largely comprises a finer 0 to 100 m thick unit of generally carbonaceous argillites, carbonatic argillites and interbedded arenites, underlain and overlain by the coarser, oxidised, clastic successions of the Mindola Clastics and Kitwe formations respectively, on the SW fringe of the Kafue Anticline. The 30 to 80 m thick Mufulira ore-bearing sandstones to the NE of the same basement high, are an inferred equivalent of the Copperbelt Orebody Member, and comprises three "Orebody Quartzites", each within a separate upward-fining unit that has conglomeratic sandstone at their bases, followed upsection by sandstone (quartzite), and culminating a mudseam, dolomitic bed or argillaceous quartzite. Mineralisation occurs either: i). predominantly as disseminations within reduced arenites immediately below a capping finer facies bed (e.g., the Copperbelt Orebody Member at Mwambashi B; the mudseams at Mufulira; the Upper Banded Shale at Nchanga); or ii). mainly veins, both parallel and oblique to bedding within a reduced fine facies, and disseminated in sandy interbeds (e.g., the Copperbelt Orebody Member at Nkana-Mindola and Konkola-Lubambe). More than one style may occur at some deposits.
   Individual ore zones within this package average 4 to 15 m in thickness (maxima of 15 to 30 m), with Nchanga an exception having an average thickness of 35 m and a maximum thickness of 91 m.
   Some 65% of the mineralisation of the Zambian Copperbelt lies within or immediately below the Copperbelt Orebody Member (e.g., Luanshya-Baluba, Mufulira, Nkana-Mindola, Nchanga-Chingola, Chambishi and Konkola-Lubambe) and the inferred equivalent Mufulira ore-bearing sandstones (e.g., Mufulira).
   A further 25% of the Zambian Copperbelt ore lies within coarser footwall clastics of the underlying Mindola Clastics Formation (e.g., at the Chibuluma deposits, where ore is capped by sandy argillites within the Mindola Clastics, whilst the Copperbelt Orebody Member and Kitwe Formation are absent, and the Mindola Clastics formation is directly overlain by the Upper Roan Subgroup; at Fitula, Mimbula and Chingola in the Nchanga district, where the ore steps upwards to the north, from the "footwall" Mindola Clastics formation, in the south, before being hosted within the Copperbelt Orebody Member at Chingola-Nchanga; and the Footwall ore below the Southern Ore Body at Nkana).
   The remaining 10% of the ore within the Zambian Copperbelt lies within the coarse "Hanging Wall" arenites of the Kitwe Formation, above the main mineralised Copperbelt Orebody Member (e.g., the large deposit within The Feldspathic Quartzite at Nchanga, where it is 15 to 40 m thick, and is capped by the Upper Banded Shale, on the northern end of the string of deposits, where the upward transition described above has passed through the Copperbelt Orebody Member into the "hanging wall");
   Lithologically, 60% of the ore in this package is hosted by argillites, and 40% in arkose, quartzites and conglomerates. Ore within this package is largely restricted to the eastern Domes Region in Zambia and southern DRC.
• The 'Lower' and 'Upper' orebody packages in the Mines Subgroup, only found in the DRC (e.g., at the Kolwezi and Tenke-Fungurume deposits), and sometimes the overlying 'Third orebody' position (e.g., Kambove-Ouest), also in the same subgroup. The Lower and Upper orebody packages overlie the red to lilac R.A.T. Subgroup and comprise two 5 to 15 m thick units of grey, laminated, fine-grained, argillaceous and chloritic dolostone to dolomitic siltstones, sandwiching a strongly silica-dolomite altered unit that is 10 to 30 m thick, originally composed of massive, porous reefal stromatolitic dolostones. The Third orebody position is 60 to 100 m above the the Upper orebody package, within carbonaceous massive to laminated dolostones. Where ore occurs in this latter position, the mineralised intervals lower in the sequence are often poor (Pelletier,1964). These rocks were deposited in the post-Lower Roan Subgroup sag phase facies of the Roan Group that transgressed northward from the main rift in Zambia, onto its margins in the DRC. For detail, see the Congolese/Katangan Copperbelt record;
• The Kansuki Formation of the Dipeta Subgroup, also restricted to hosting ore in the DRC (e.g., Mutanda and Deziwa), are part of the Roan Group sag phase facies, deposited at the transition to renewed extension. It comprises a generally >80 m thick sequence, mostly separated from the underlying Dipeta sequence by a structural contact, marked by an evaporite-facilitated breccia-detachment. It is characterised by alternating reefal to intertidal deposition, comprising laminated and massive stromatolitic or arenaceous dolostones, oolitic dolostone, erosional surfaces, intraformational conglomerates and pseudomorphs after anhydrite near the top of the formation. The Kansuki Formation also contains ~765 Ma (Key et al., 2001) mafic lavas, and extensive, 2 to 12 m thick beds of associated pyroclastic flows and volcaniclastic rocks interbedded with dolostones, defining a regional 'volcanic belt'. This sequence is underlain by the R.G.S. Formation, at the base of the Dipeta Subgroup, containing oxidised clastic rocks, similar to those of the R.A.T. Subgroup.
   Ore zones are generally thicker than in the other Copperbelt mineralised positions, but with correspondingly lower grades. Thicknesses of ore as defined by a 0.4% Cu cut-off vary from a few, up to 150 m, with grades of ~1.4% Cu and 0.1 to 0.6% Co (e.g., Mutanda and Deziwa).
   Where the Kansuki Formation hosts major deposits, it is uncertain if the Mines Subgroup is developed below, although it may only be represented by the normally barren Menda facies. For detail, see the Congolese/Katangan Copperbelt record;
• The Mwashya Subgroup in Zambia (e.g., Kansanshi) and DRC (e.g., Frontier), deposited in the deepening Katangan basin during the main episode of renewed extension and northward migration of the depocentre. The main prospective unit is the central, ~75 to 140 m thick Kafubu Formation, a sequence of finely bedded, grey to dark grey or black, pyritic carbonaceous shales with local sandy, silty and dolomitic interbeds. At Frontier, the normally underlying Lower Roan hosts are absent, and the Mwashya Subgroup represents the first reduced unit overlying an oxidised arenite sequence separating it from the basement. At Kansanshi, the underlying Lower and Upper Roan subgroups are exposed on the margins of the Solwezi Dome, 12 km to the south;
• The Grand Conglomérat of the basal Nguba Group (e.g., Kamoa in the DRC, Fishtie in Zambia, and to a lesser extent at Frontier in the DRC). Mineralisation extends into the lower Kakontwe Limestones at Fishtie. Like the Mwashya Subgroup, the Nguba Group was deposited during the 'renewed extension', as the Katangan Basin continued to deepen and spread outward onto the Kibaran and Irumide basement to the NW and SE respectively, without any underlying Roan Group, other than a thin oxidised conglomeratic wedge of Mwashya Subgroup at Kamoa.
   At Kamoa, the Grand Conglomérat comprises a 'basal diamictite package', commencing with 0 to 30 m thick, clast-rich, sandy diamictite, overlain by 0 to 5 m of sandstone-siltstone to lithic greywacke and by 0 to 15 m of clast-poor, silty/muddy and weakly carbonaceous diamictite. This package hosts the bulk of the resource, and it is uncertain how much original pyrite was in the rock, prior to the introduction of the copper sulphides. It is overlain by a 15 to 45 m thick, dark, pyritic, siltstone-sandstone unit, which is predominantly well stratified and laminated, with bedded pyrite and little Cu sulphide. These are overlain by 0 to 900 m of diamictites and pyritic siltstones, and then by the Kakontwe Limestone (For detail, see the Congolese/Katangan Copperbelt, Kamoa and Fishtie records).
• The Kundelungu Group - a number of transgressive, relatively small, but high grade vein deposits are found outside of the main Lufilian Arc in the northern part of the Kundelungu Gulf/Foreland e.g., Dikulushi (1.138 Mt @ 8.11% Cu, 238 g/t Ag) hosted in the Ks-1 Kalule Subgroup); Kapulo group of deposits (4.2 Mt @ 3.4% Cu), 100 km to the NE, hosted within the underlying mid to upper Nguba Group Monwezi Subgroup).
  No major stratabound Cu-Co deposits have yet been found (to 2015) higher than the Grand Conglomérat, although late stage pitchblende and uraninite veins penetrate overlying Nguba and Kundelungu group rocks at Shinkolobwe and related deposits both in the DRC and Zambian Copperbelt, while late stage Pb-Zn ore at Kipushi and similar occurrences to the south of the main Cu-Co zone in the DRC (e.g., Kalongwe) are also hosted by rocks at higher stratigraphic positions within the Nguba Group. Late stage Pb-Zn ore is also found in Upper Roan Subgroup carbonate rocks at the Kabwe group of deposit, ~150 km of the main Zambian Copperbelt.

Sulphur and Sulphates
   Anhydrite, dolomite and calcite are common throughout the Roan Group, occurring as coarsely crystalline anhydrite-dolomite beds, patchy to pervasive authigenic cements, replacive grains, nodules (up to several cm diameter), alteration products and as veins. They are most abundant within the Kitwe Formation and Upper Roan Subgroup, where they are probably of evaporitic origin. Widespread discordant and semi-concordant breccias within the Upper Roan Subgroup have been interpreted to have resulted from the dissolution of extensive halokinetic remobilised evaporites. Based on the thickness of breccias that are thought to represent original evaporite beds, and the absence of diapiric structures, it is calculated these evaporite beds were originally <500 m thick (Selley et al., 2005 and sources cited therein). The Upper Roan Subgroup, in the hanging wall of the main Zambian Copperbelt ore deposits, appears to contain the first significant primary evaporite beds in the Katanga Supergroup of Zambia.
   However, anhydrite, dolomite and calcite are also present, within non-evaporitic deltaic and shallow marine lithologies of the Lower Roan Subgroup, mainly as authigenic cements (van Eden, 1974), e.g., a). ±30% anhydrite filling pores within the Porous Conglomerate member and other arenites of the Mindola Clastics Formation; b). quartz-dolomite-anhydrite veinlets in the lower Copperbelt Orebody Member argillites of the basal Kitwe Formation; and c). 20 to 30% anhydrite in the Mufulira ore-bearing sandstones. These include the main ore bearing units.
   The presence of this assemblage in the non-evaporitic units of the Lower Roan Subgroup, below the only interpreted significant primary evaporitic source, has been postulated to be the product of diagenetic brine reflux, whereby dense Mg-Ca-SO4 brines, sourced from the overlying evaporitic Upper Roan Subgroup, sink to displace, lighter fresh pore waters, and precipitate interstitial evaporite minerals (Selley et al., 2005 and references cited therein).
   Anhydrite from throughout the lower section of the Katangan Supergroup, both primary evaporites and disseminated sulphates in non-evaporitic units, has sulphur isotope values of 11.0 to 25.6‰, mostly between 14 and 19‰ (Dechow and Jensen, 1965; Claypool et al., 1980; Surman, reported in Annels, 1989; Hitzman and Broughton, unpub. data), compatible with published Neoproterozoic sea water δ
34S sulphate values (Hurtgen et al., 2002).
   As there is no evidence of a widespread magmatic sulphur source, and as sulphides can be widely observed replacing anhydrite disseminations and nodules, the source of sulphur in the Zambian Copperbelt has been interpreted to most probably be the disseminated anhydrite within the host rocks, derived from sea water sulphate, or sulphate redeposited from evaporite beds during early diagenesis.
   There is a marked antithetic relationship between anhydrite and ore, which is taken to reinforce the interpretation that anhydrite may represent an in situ source of sulphur in ore minerals and was 'consumed' in the process of ore formation, to produce sulphides and a dolomite gangue, as described above. Authigenic anhydrite nodules and crystals show progressive to total replacement by ore sulphides and gangue dolomite/carbonates at the lateral transition to ore (Hitzman et al., 2012; Selley et al., 2005; Sweeney and Binda, 1989; Annels, 1974).
   However, sulphides of the Zambian Copperbelt ore deposits have irregular intra- and inter-deposit distribution trends and large ranges of δ34S sulphate values, ranging from -18.4 to +23‰ (Dechow and Jensen, 1965).
   Never-the-less, trends are evident, e.g., sulphides in late-formed veins commonly have δ34S values heavier than those of earlier disseminated or veinlet sulphides (Annels, 1989; McGowan et al., 2003), locally at the upper range of assumed sea water values (21 to 23‰). Sulphides in late shear zones also may be heavier relative to nearby disseminated sulphides (Dechow and Jensen, 1965; Hitzman, unpub. data). These data suggest that sulphur isotope values became heavier with time.
   Average isotopic fractionation (Δ
SO4-sulphides) values for the arenite-hosted deposits are anomalously low, averaging from 5 to 6‰, at three examples, Chibuluma, Chibuluma West and the Nchanga Upper orebody. Fractionations for argillite-hosted deposits are higher, ranging from ~10.8‰ at Chambishi South East, to ~30‰ for the Luanshya deposit.

Source of Metals
   A number of authors have proposed that the copper-cobalt mineralising fluids in the Zambian Copperbelt were derived from leaching by brines of early rift-cycle red beds of the lower Katanga Supergroup (Mindola Clastics Formation), containing mafic volcanic rocks and/or labile mafic detritus (e.g. Brown and Chartrand, 1986; Haynes, 1986; Rose, 1989; Walker, 1989; Jowett, 1989; Kirkham, 1989). However, Hitzman (2000), Selley et al. (2005), Cailteux et al. (2005), Kampunzu et al. (2005) and others agree that these rocks occupy insufficient volume by more than an order of magnitude to supply the volume of copper within the Central African Copperbelt. In addition, they do not have an appropriate composition, i.e., they lack mafic volcanic rocks and/or significant labile mafic detritus.
   Kampunzu et al. (2005) estimated the contained copper, within past production and known resources (152 Mt in 80 deposits; Zientek et al., 2013), allowance for undiscovered deposits (~168 Mt; Zientek et al., 2013), plus subeconomic and anomalous copper accumulations between and surrounding these deposits, totalled ~1850 Mt, which would require the leaching of ~25 ppm Cu from a volume of ~10
14 m3 (~100 000 km3) of source rock.
   To leach this volume of rock, would require the inclusion either a significantly greater portion of the Katangan Supergroup stratigraphy, possibly including basement rocks, or an adjacent thicker basin succession. Selley et al. (2005) conclude that, based on the extent of observed alteration throughout the rocks of the Lower and Upper Roan, and Mwashia subgroups, and of the uppermost basement, metal leaching from these units above and below the level of ore (a thickness of ~1500 m) would be plausible (i.e., over an area of ~ 200 x 300 km).
   Selley et al. (2005) suggest leakage of basement fluids via major rift-related fault systems along the basin margin, provides input from a much larger potential metal reservoir (e.g., Annels, 1989). Authors such as Sweeney et al. (1991) have argued that copper occurrences in basement rocks were the most likely source of copper for the deposits of the Zambian Copperbelt. However, the most significant of these, Samba (see Basement mineralisation below) has been shown to be Lufilian in age, and others are due to replacement into weathered basement in the immediate footwall of the main stratabound deposits, while others have similar gangue assemblages to the intrabasinal deposits, and many lie close to the basal unconformity of the Katangan Supergroup. These are therefore likely to be related to passage of fluid from basement during the main Copperbelt mineralising episode, rather than a source of copper (Selley et al., 2005).
   Selley et al. (2005) quote estimates of µ values (
238U/204Pb) for potential basement source reservoirs from Carr et al. (unpub. 1986) quoted in Sweeney et al. (1991), and analysed by Kamona et al. (1999). Three end-member source reservoirs were considered (after Kamona et al., 1999): a). upper continental crust Pb from Palaeoproterozoic Lufubu Metamorphic Complex schist and granodiorite (µ = 10.38 and 10.21, respectively); b). average crustal Pb for the Neoproterozoic Nchanga Red Granite (µ = 9.756); and c). upper mantle Pb for the intrabasinal gabbros (µ = 9.451). Stratabound chalcopyrite and carrollite from all deposits sampled yielded µ values of between 10.14 and 10.31 (Richards et al., 1988; Kamona et al., 1999). Regionally, these µ values increase southwards from Konkola to Luanshya, both in basement rocks and in Katangan stratabound sulphides from the ores (Carr et al., reported in Sweeney et al., 1991). These data are consistent with derivation of lead in the ore systems from local basement rocks or locally eroded basement sources.
   The broad coincidence of cobalt mineralisation and the gabbroic corridor in Zambia was noted by Annels, (1974; 1984; 1989). If a common source for Pb, Cu and Co is assumed, a source from mafic rock is not supported by this Pb isotope data. However, the main Pb phase within these orebodies is paragenetically late, and may not necessarily be directly related to the main Cu-Co phase.
   A study by Richards et al. (1988) analysed copper sulphides from stratabound ore and rutile in uraniferous ~500 Ma post-peak metamorphic veins at Musoshi. Rutile from these veins yielded a µ value of 9.7, suggesting that these late veins derived Pb (and possibly also Cu) from a different source than the earlier ore-stage.

Reductants and Redox Boundaries
   Mineralisation within the Zambian Copperbelt is closely associated with stratigraphic or structural redox boundaries in the host units described above, related to rocks that may have contained reductants and that overlie coarse, permeable, oxidised arenites. The redox boundaries are related to reductants that may be either i). in situ largely occurring relatively dark and locally carbonaceous siltstones and argillites, often with fine arenite interbeds; or ii). mobile e.g., sites that are geometrically favourable to the entrapment of liquid hydrocarbons or sour gas. These rocks acted both as a cap to fluid flow within the coarse clastic sediments, and as a redox boundary and reductant, catalysing the release of Cu from oxidised fluids. Pyritic, carbonaceous rocks, with few exceptions, form a barren cap and or mark the lateral margins to ore, as well as in some cases, a barren footwall.
   Of the major deposits, Luanshya, Nkana-Mindola, Chambishi, Konkola-Lubambe and in part Nchanga, are hosted by the Copperbelt Orebody member which is taken to represent a unit that contained in situ hydrocarbons. Deposits of this type are laterally extensive with strike lengths up to 17 km. The deposits hosted by Mwashya Subgroup (e.g., Frontier and Kansanshi) and Nguba Group (Fishtie in Zambia and Kamoa in DRC) are also most likely associated with in situ hydrocarbons.
   Deposits interpreted to be related to accumulation of mobile hydrocarbons are usually arenite-hosted deposits which occur in both the footwall, hanging wall and equivalents of the Copperbelt Orebody member, and have maximum strike lengths of 5 km. Deposits of this type include Mufulira and much of the Fitula-Mimbula-Chingola-Nchanga string of deposits, as well as Mwambashi B and the Chibuluma deposits.
   No direct evidence of mobile hydrocarbons has been recognised, e.g., pyrobitumen, although nterstitial carbonaceous matter in the arenites hosting orebodies at the Mufulira deposit, and the strongly depleted carbon isotope signature of carbonate gangue at the Mufulira and Mwambashi B deposits are taken as indirect evidence for the involvement of hydrocarbons in the mineralising process (Selly et al., 2005).
   On the eastern margin of the Kafue Anticline, a thick carbonaceous arenite unit, occurs at the same stratigraphic position as the Mufulira arenite hosted ore deposit, and forms the lateral gradational margin to mineralisation. The carbonaceous matter, which is finely disseminated throughout this sandstone suite, is interpreted to have originated as mobile hydrocarbons based on δ
13C and δ18O values (see below; Annels, 1979; 1989). It transgresses bedding and is continuous over a strike length of >16 km, capped by less permeable shale and dolomite interbeds. Similarly, the string of deposits from Fitula, through Chingola and Nchanga gradually climbs through the sequence from the Mindola Clastics Formation in the south, to the hanging wall of the Copperbelt Orebody member of the Kitwe Formation 18 km to the north, much of which is hosted by arenites, capped by argillite bands.
   The location, geometry and size of deposits, particularly those related to mobile hydrocarbons are fundamentally controlled by early sub-basin fault architecture and the supply of the reductants, which are also linked to basin architecture (Selley et al., 2005). The most common interpreted trap sites for mobile hydrocarbons include: i). where the argillites of the Copperbelt Orebody member lap onto basement up-dip, over a pinchout wedge of Mindola Clastics formation rocks; ii). early Lufilian antiformal culminations, as postulated at Nchanga and iii). culminations resulting from differential compaction of sediments over, or lapping onto a localised composite basement high, as at Mufulira, due to a lesser decrease in thickness of thinner sections over underlying basement hills (usually of granite), compared to the greater cumulative reduction in thickness over intervening basement lows (usually over Lufubu schists).
   Mobile hydrocarbons are generated when organic rich rocks (usually argillites containing 4 to 20 wt.% total organic carbon) are heated to ~60°C, when petroleum begins to form in the source rock by the thermogenic breakdown (cracking) of organic matter (kerogen) known as maturation. The temperature dependant oil window, or interval over which oil is generated and expelled from the source rocks, is ~60 to 120°C. The succeeding gas window occurs over the temperature range of ~100 to >200°C. These temperatures are usually the result of burial, which at the typical thermal gradient of ~30°/km, is 2 to 4 km for the oil window and 3 to 6 km for the gas window. In addition, large intrusions may supply sufficient heat to complement the thermal gradient to reach the required temperature window at shallower depths.
   Consequently, where mobile hydrocarbons are the indicated redox agent, mineralisation did not take place until the organic rich source rocks had been buried to sufficient depths to promote maturation. If those source rocks were from the Katanga Supergroup, such a thickness was not achieved in the immediate Zambian Copperbelt until late in the deposition of the Kundelungu Group during the early Lufilian Orogeny. If the hydrocarbons were formed in a deeper core of the Katanga Basin to the SW (or NW), where the host sequence may have been thicker, and then migrated up dip, this could have occurred earlier, most likely during deposition of the Nguba Group. This corresponds to the period of 'renewed extension' and deepening of the Katanga basin, when deeper water, more reduced equivalents of the Roan or Lower Nguba groups were buried and dropped to well below the level of the basin margins, and may have acted as source rocks. This would include potential source rocks such as the carbonaceous argillites of the Copperbelt Orebody Member and the Mwashya Subgroup. The extensive gabbro corridor rocks in Zambia and coeval mafic volcanic rocks in DRC, as described above, which were emplaced during the 'renewed extension' and deposition of the Mwashya Subgroup and Nguba Group, may also have contributed to maturation of source rocks.
   Alternatively, potential source rocks in the Mesoproterozoic Irumide and Kibaran sequences would have passed into the 'oil window' earlier in the deposition of the Roan Group sequence and migrated up section along extensional structures. Whichever may have occurred, mobile hydrocarbons would not have been introduced to the host sequence until late- or post-diagenesis, after lithification had commenced, when porosity and permeability were facilitated by both interstitial/intergranular space that remained open, and early brittle fracturing.
   Throughout the Zambian Copperbelt, the most carbonaceous rocks within an ore horizon are commonly not economically mineralised, i.e., there is an antithetic relationship between carbonaceous rocks and ore. This implies the carbonaceous reductant is 'consumed' during the ore forming process, as explained below. Also, where deposits occur in the stratigraphically lowermost reduced rocks (e.g., the Copperbelt Orebody Member), any overlying reduced or favourable rocks (e.g., the Mwashya Subgroup) were generally not mineralised. Conversely, deposits within higher stratigraphic level reduced rocks (e.g., the Mwashya Subgroup) are found where underlying reduced units are absent.
   The antithetic relationships between copper sulphide mineralisation and both carbonaceous material and authigenic anhydrite (described below under Alteration) within host units, suggests both carbon and anhydrite were an integral part of the formation of ore. Mobile hydrocarbons within a hydrocarbon reservoir react with authigenic anhydrite cements (using methane as generic hydrocarbon), to produce H
2S (sour gas) in the first instance: CaSO4 + CH4 → CaCO3 + H2S + H2O. The second step involves interaction with a Cu-bearing brine, with a most likely chloride ligand, as follows: H2S + 2 CuCl → Cu2S + 2 HCl.
   In the event of a Cu-bearing brine reacting with in situ carbonaceous material and entrained authigenic anhydrite cements, the process becomes: CaSO
4 + CH4 + 2 CuCl → Cu2S + 2 HCl + CaCO3 + H2S + H2O.
   However, in both cases, the HCl produced breaks down the CaCO
3 and reverses the process. But, where excess Fe, Mg or Mn ions are present within the brine, the HCl is neutralised and the process becomes: CaCO3 + (Mg/Fe/Mn) + HCl → CaCl + (Mg/Fe/Mn)CO3 + H2O (Orr 1974 and Irwin, et al., 1977). This process destroys both the anhydrite and carbonaceous matter, where ore is formed, and produces a gangue of dolomite, ankerite, siderite, etc., deficient in free carbon and anhydrite, as is observed.
   These formula represent the simplified process from ingredients to final products. However, it is apparent that the process took place in a chain of reactions from early pyrite, through chalcopyrite, bornite to chalcocite, as outlined in the Paragenesis and Zoning sections below.
   Annels (1989) recognised that light δ
13C and δ18O values can be the result of temperature effects during hydrothermal alteration, from the incorporation of isotopically light C and O, produced by oxidation of organic matter (in situ or mobile hydrocarbons), into secondary carbonates during low-temperature (~60 to 80°C) bacterial sulphate reduction, or from high temperature (>100°C) thermochemical sulphate reduction as in the processes outlined above.
   Selley et al. (2005) collected δ
13C and δ18O data from 369 carbonate samples (whole rock, veins and evaporite nodules) from 10 deposits and one regional drill hole, spanning the stratigraphic interval from rocks of the Mindola Clastics Formation to those of the Mwashya Group. These data revealed that samples from both ore zones and the immediate hanging walls to ore zones, have consistently light isotopic signatures compared with normal sedimentary values found in primary clastic and carbonate rocks (including 'barren gap' dolostones). Carbonates from the argillaceous rocks of the Copperbelt Orebody Member, and Mindola Clastics Formation contain a broad range of isotopic values (δ13C ~ -26 to +3‰ and δ18O ~ +7 to +23‰). However, strongly depleted isotopic values (δ13C < -14‰ and δ18O <+13‰) are entirely restricted to ore zones. There are a number of possible ways to produce this result, which Selley et al. (2005) discuss, but conclude that the most plausible is oxidation of organic matter to CO2 which then becomes incorporated in diagenetic or hydrothermal carbonates (e.g., Rollinson, 1993; Ohmoto and Goldhaber, 1997; Wilson et al., 2003).

Ore Fluids
   Salinities of fluid inclusions (Selley et al., 2005 and references cited therein) increase from:
• 11 to 21 wt.% NaCl
equiv. and homogenisation temperatures of 110 to 170°C, from diagenetic early mineralisation (chalcopyrite-bearing carbonate nodules and subconcordant veins at the Chambishi and Chambishi South East deposits; Annels, 1989), to
• 21 to 38 wt.% NaCl
equiv. and homogenisation temperatures of 155 to 185°C, from folded veins cutting stratabound ore (unmineralised, high-angle and deformed quartz±carbonate-K-feldspar-pyrite veins cutting the Lower and Upper orebodies, at the Nchanga deposit; McGowan, 2003), to
• ~39 wt.% NaCl
equiv. and homogenisation temperatures of ~400°C for late ~500 Ma veins interpreted to be related to mineralisation at Musoshi, interpreted to represent feeders for copper mineralising fluids (Richards et al., 1988).
  This trend indicates an increase in salinity and temperature with time. These fluid inclusions are the product of reactions between three components, namely the sulphur source (most likely authigenic sulphate in the Zambian Copperbelt), a reductant (either in situ or mobile) and the copper bearing fluid (an oxidised brine), rather than representing a single ore fluid.

Mineralisation Styles and Textures
   Deposits have a range of differing mineralisation styles and textures that may occur together or alone. The chief of these are:
• Disseminated, generally fine-grained (<0.1 to 3 mm) sulphides within interstitial sites between detrital or authigenic grains, randomly distributed or aggregated to form bedding-parallel streaks and lenses of blebs. There is a correlation between the size of detrital and sulphide grains in this style of dissemination (Selley et al., 2005 and references cited therein). Sulphides may also occur replacing detrital grains and authigenic cements, including anhydrite, carbonate, quartz and feldspar, as well as diagenetic pyrite, anhydrite, carbonate, quartz, feldspar or heavy minerals such as rutile (Binda, 1975; Fleischer et al., 1976). Disseminated ores predominate in porous and permeable host rocks such as sandstones, coarse silts or shales with sandy interbeds (Hitzman et al., 2012);
• Vein-hosted, which may occur as prefolding, layer-parallel and discordant veins or veinlets of sulphide, which have sharp contacts with argillaceous strata, and diffuse margins in arenites (Annels, 1989). Prefolding vein-dominated deposits occur within strongly carbonaceous host rocks which lack economic disseminated mineralisation, and may consist entirely of sulphides or be accompanied by other minerals, particularly quartz and dolomite, with lesser K feldspar, albite, chlorite, sericite, phlogopite and anhydrite (Hitzman et al., 2012).
   Veining also occurs as late-tectonic, generally coarse-grained sulphide grains (commonly >0.5 to 3 cm) in quartz-carbonate (dolomite, calcite) veinlets and subordinate veins, which may also contain K-feldspar, chlorite, sericite, biotite, and, very locally, albite, tremolite, and below the zone of supergene dissolution, anhydrite. Veinlets are typically ~0.5 to 2 cm wide, but may locally be up to several tens of cm thick and extend for distances of several tens of metres or more, with densities of 1 to 5 per metre, following and stepping up through the stratigraphy. Veins also occupy tension gashes on a small scale and other structures at a high angle to bedding. Veins and veinlets can be particularly abundant at the tops and/or bottoms of the stratabound orebodies, commonly coinciding with rheologic contrasts and occupying shear zones and décollements at the boundaries between more argillaceous and siliciclastic rocks. Veinlets often penetrate upwards from arenite hosted disseminated mineralisation into otherwise unmineralised, impermeable carbonaceous shales.
   Mineralised veins are restricted to zones of disseminated mineralisation, and contain the identical sulphide assemblages found within the enclosing disseminated mineralisation throughout the zoned sulphide assemblages (Hitzman et al., 2012, and references cited therein; Sillitoe et al., 2010).
   In addition to these Cu±Co vein systems, the Zambian Copperbelt contains volumetrically minor Cu-U-Mo-(Au)-(Ni) sulphide assemblages in post-folding veins with associated albite haloes, e.g., Mindola, which is the only known economic accumulation (Darnley et al., 1961). Generally sub-economic uranium occurs as late veins and local disseminations of pitchblende, uraninite, brannerite, coffinite and secondary oxide minerals below or adjacent to copper mineralisation (Selley et al., 2005).
•  oxide ores, usually gradationally overlying the hypogene mineralisation, through a progression from primary sulphide (chalcopyrite-bornite-carrollite), through mixed oxide-sulphide (chalcocite-copper carbonate/sulphate-cuprite-native copper) to leached capping (usually ~30 m thick). The transition usually takes place over an interval of 30 to 70 m below the surface, although in some areas of deep faulting, malachite and chalcocite have been found to persist to depths of as much as 1 km at Konkola and >600 m at Nchanga Lower. As chalcocite generally occurs closest to the surface in the primary sulphide zonation, it is often difficult to differentiate between primary and supergene populations of the mineral (Selley et al., 2005).
•  cupriferous mica mineralisation, which occurs at a number of deposits as an upper and/or lower fringe to sulphide orebodies, but never laterally. At the Mimbula-Fitula deposits, cupriferous micas persist to a depth of up to 150 m, although the bulk is in the zone from near surface to a depth of 60 m. The cupriferous micas are brown to dark brown in colour, and are visually indistinguishable from unmineralised mica. Stockpiles of as much as 150 Mt @ 1.2% Cu have been accumulated at Chingola, and resources of in situ mineralisation and stockpiles at Nchanga are >275 Mt @ 1 to 1.4% Cu. The mineralisation is refractory. Copper is held in the mica lattices in the exchange position, tied largely to hydroxyl groups in interstratified phlogopite-cupriferous chlorite micas. Some copper is also absorbed on the surfaces of layered mineral structures. Under tropical or sub-tropical conditions of weathering, it has been shown that copper may be dissolved out of primary minerals, and where the adjacent rock is micaceous, Cu is 'soaked up' by the micas as it passes through the rock. Weathering of primary phlogopite causes exchanges of K ions by hydrated Cu and Mg ions, followed by chloritisation. The Cu content of this mineralisation ranges from 1 to 8% Cu (Diederix 1977).

   Prolonged, repeated, multiple stages of alteration are evident within the Zambian Copperbelt, ranging from diagenetic overgrowths, to post-metamorphic vein selvedges, reflecting the similarly prolonged history of Cu mineralisation. Three dominant alteration types are widespread throughout the Copperbelt, controlled partly by lithology and indicative of the large scale passage of basinal brines. These are (after Selley et al., 2005 and references cited therein):
•  Calcic-magnesian - an early diagenetic to early lithification, dominantly pre-ore, alteration suite, characterised by anhydrite, dolomite, calcite and later development of phlogopite. Anhydrite, dolomite and calcite are common throughout the Roan Group, as described above in the Sulphur and sulphates section, e.g., a). ±30% anhydrite filling pores within the Porous Conglomerate member and other arenites of the Mindola Clastics Formation; b). quartz-dolomite-anhydrite veinlets in the lower Copperbelt Orebody Member argillites of the basal Kitwe Formation; and c). 20 to 30% anhydrite in the Mufulira ore-bearing sandstones. There is a marked antithetic relationship between anhydrite and ore, as described above in the Sulphur and sulphates section.
  The widespread development of phlogopite (KMg
3AlSi3O10)(F,OH)2), particularly in argillites, is suggested by Selley et al. (2005) to represent later isochemical metamorphism of previously pervasively magnesian metasomatised rocks throughout the succession. Within the Upper Roan and Mwashya subgroups, and the lower Nguba Group, above the main evaporite horizons, local significant albitisation and silicification accompanies the calcic-magnesian phase.
•  Potassic - characterised by K feldspar and sericite-muscovite. The feldspar content of detrital rocks within the Lower Roan Subgroup is virtually 100% potassic, at variance with the high sodic feldspar content of the source basement rocks. This and textural features of the rocks (e.g., the partial to total replacement of plagioclase detrital grains), are interpreted to be the result of intense K metasomatism of the Lower Roan Subgroup. Textures indicate multistage K feldspar replacement which took place from diagenesis (as pre-anhydrite-carbonate overgrowths) to orogenesis (vein-hosted K feldspar). Secondary K feldspar is a major gangue mineral in many Zambian Copperbelt deposits, typically intergrown with Cu-Co sulphides, particularly in argillite hosted deposits where sulphides and K feldspar are intergrown in coarse clots throughout the detrital network. In addition, there is a concomitant increase of the the K
2O:Al2O3 ratio and Cu within rocks of the Copperbelt Orebody Member. However, elevated K2O:Al2O3 ratios persist for hundreds of metres into the hanging wall of mineralisation and for kilometres laterally beyond the margins of ore (Selley et al., 2005). The formation of sericite, in close association with Cu-Co mineralisation, at the expense of K feldspar (and Ca-Mg-bearing minerals), is evident at a number of (but not all) deposits, particularly those hosted by arenites (e.g., Mufulira). This has been taken to reflect evolving conditions in the potassic environment, resulting from a more acid phase, possibly associated with H2S in sour gas within the sandstones, and/or generated from the reaction between Cu-bearing fluids and anhydrite and/or the progressive enrichment of Cu in sulphide minerals (see the reactions outlined in the Zoning section below). In these deposits, the sericite alteration is much more closely associated with the ore mineralisation than potassic alteration is elsewhere. Sericite is also localised along faults and shear zones at a number of deposits (Selley et al., 2005).
•  Sodic - late-stage, structurally controlled alteration, usually as structurally controlled vein-associated, albite and/or scapolite. Secondary albite alteration dominates in rocks above the evaporite horizons in the Upper Roan and Mwashya subgroups and the lower Nguba Group. However, it is relatively rare in the Lower Roan Subgroup, occurring in some 'footwall' arenite-hosted deposits (e.g., Chibuluma), where the Upper Roan section containing breccias interpreted as after evaporites, has been stepped down to be juxtaposed with the Mindola Clastics Formation.
   Within the Zambian Copperbelt, sodic alteration is associated with late events, e.g., as a halo to discordant, post-folding, barren to sub-economic vein-fracture zones superimposed on the stratabound ore, as at Chambishi and Musoshi, but also as albite associated with an increase in economic mineralisation elsewhere in the same deposits, associated with shearing at the base of the Copperbelt Orebody Member. Albite is developed as a partial replacement of secondary K feldspar and sericite, and occurs both in equilibrium with, and overprinting, Cu-Co sulphides at different deposits.
   A late, post-peak metamorphic paragenesis is indicated, where geochronological and geological data is available, for some vein and fracture-related albite alteration, such veins contain molybdenite (e.g., Chambishi Ore Shale, Jolly, 1971; or Musoshi Ore Shale, Lefebvre and Tshiauka, 1986; Richards et al., 1988), or that introduce late U-Mo-Cu-(Au) (e.g., Mindola, Darnley et al., 1961). Veins of this type in the footwall of the Musoshi orebody were dated at ~514 Ma (Richards et al., 1988). Albite alteration is associated with post-folding quartz-dolomite-chalcopyrite ore veins at the Kansanshi deposit (dated at ~510 Ma; Torrealday et al., 2000) and is the main alteration phase at the Frontier deposit (Broughton, unpub. data, 2004).
•  Regional IOCG-style - comprising sodic and sodic-calcic (albite-actinolite-scapolite) alteration that overprints the pervasive potassic altered rocks of the region, as does regionally distributed occurrences of Cu, Cu-Au, Au, magnetite/hematite and U. The sodic stage described above, is part of this regional alteration. This alteration and mineralisation occurs in the following regions:
  a). the Katanga Core, centred on the ~560 Ma Hook Granite and associated younger ~530 Ma phases and syenites, and include the Mumbwa/Kitumba Cu deposit (Resources of 38.8 Mt @ 2.19% Cu at a 1% Cu cutoff; Blackthorn Resources website, 2012) and the Kasempa Fe deposit (~230 Mt @ 66% Fe in 10 deposits; Nisbet, et al., 2000). These deposits are associated with vertically oriented, structurally-controlled magnetite-hematite-rich breccia zones in Nguba Group sedimentary rocks and 'Hook' granites and syenites (Hitzman, 2001). Gabbro, as well as syenite is also found at some of these occurrences (e.g., Kalengwa, 1.9 Mt @ 9.44% Cu, 50 g/t Ag; Lobo-Guerrero, 2010). At Mumbwa, potassically altered rocks are cut by magnetite, which is in turn replaced by hematite during a hydrolytic (sericite-chlorite) alteration event, overprinted by a final sulphidation event resulting in the precipitation of pyrite and then chalcopyrite (Lobo-Guerrero, 2010; Hitzman, 2001);
  b). the Domes Region, extending from southern DRC and western Zambia, to and overlapping the southern Kafue Anticline. Massive magnetite bodies are associated with mafic intrusive stocks or sills (gabbros) which have undergone extreme sodic alteration, resulting in the formation of albite-actinolite-scapolite assemblages. Hitzman (2001) notes that Cu-(U-Au) deposits associated with intense sodic alteration (e.g. Kansanshi) are also present in this part of the Lufilian arc, and although these deposits lack significant iron oxides, the intense sodic alteration is somewhat similar to that observed in many magnetite-apatite systems (Hitzman, 2001). This belt of Fe, Cu, Au and U occurrences forms an inner arc SW of the Zn-Pb zone (e.g., Kipushi and Kalongwe) and the outer main Lufilian Arc Zambian and Congolese copperbelts Cu-Co deposits to the NE;
  c). The Irumide Belt, south of the Kafue Anticline, where the Fishtie (55 Mt of 1.04% Cu at a 0.5% Cu cut-off; Hendrickson, 2014) deposit is located. At Fishtie, stratabound, replacement magnetite-ankerite-apatite-quartz mineralisation hosted by the Grand Conglomérat of the basal Nguba Group, was overprinted by later hydrothermal alteration and sulphide mineralisation. The stratabound early iron phase tapers outwards from steep syn-sedimentary faults. The overprinting sulphide and Cu mineralisation is spatially closely controlled by, and is not extensively developed distal to, the same faults, but is zoned relative to them, from proximal bornite, outward to ore stage pyrite with chalcopyrite. This deposit has characteristics of both IOCG and sediment hosted mineralisation, but lacks a thick siliciclastic palaeoaquifer beneath the Grand Conglomérat Formation as is present at Kamoa deposit which is in a similar setting in the DRC (Hendrickson et al., 2015);
  d). the Zambezi Belt, south of Lusaka.
   These observations suggest two IOCG events occurred in the broader Lufilian Arc, one during the 'renewed extension' (~765 to 736 Ma) and the second during the late Lufilian orogenesis (~560 to 530 Ma), both of which contributed fluids that produced either IOCG sensu stricto deposits, or overprinted earlier sediment hosted copper mineralisation, or produced hybrids with the characteristics of both styles.

   Croaker (2011) determined the following paragenesis for the Nkana deposit in Zambia:
• Pyrite - the earliest sulphides are a disseminated pyrite phase, which is interpreted to be of late diagenetic origin, typically replacing earlier diagenetic anhydrite and/or dolomite (Annels, 1989).
  Diagenetic framboidal pyrite is widespread in both Zambian and Congolese copperbelts, but is not always accompanied by Cu-Co ore (Sweeney and Binda, 1989; Dewaele et al., 2006). Croaker (2011) identified a number of pyrite types in the Chambishi Basin deposits. These included pyrite grains hosted within black carbonaceous argillite, with 'spongy' cores, and the isotopically lightest sulphur signatures, at the poorly deformed Chambishi SE deposit, 10 km to the north, interpreted as typical of early diagenetic origin. At the more heavily metamorphosed Nkana deposit, fine grained (~0.1 mm or less) disseminated pyrite is observed in low strain zones, interpreted to be late diagenetic. This is suggested by the rotation of some equivalent, but coarser (0.2 to 10 mm), inclusion free pyrite porphyroblasts, with quartz-calcite strain shadows in high strain domains, suggesting they are pre-tectonic. In addition, a further variety of disseminated pyrite with inclusions of mica laths aligned parallel to the regional structural foliation is taken to be syn-tectonic.
  Similarly, late diagenetic, (pre-kinematic), syn-tectonic and late-tectonic (or recrystallised) pyrite veins were identified, based on their structural relationships. These later generations may not represent introduction of new pyrite, but recrystallisation and the localised deformation and remobilisation of the sulphides on the scale of centimetres to metres within the confines of the stratabound copper ore envelope. Locally pyrrhotite dissolves and partially replaces pyrite along cleavage and fracture planes in the high strain domain.
• Copper sulphides - predominantly chalcopyrite, with lesser bornite and carrollite. An early phase of chalcopyrite and carrollite overgrows and/or replaces pyrite, whilst chalcopyrite locally displays myrmekitic, vesicular and exsolution textures with bornite. A second generation of chalcopyrite-bornite frequently overgrows carrollite, or encloses fractured carrollite. A volumetrically minor late stage of carrollite, confined to the high strain domain, overgrows both chalcopyrite and bornite. A minor bornite phase may contain exsolved or pseudomorphic intergrowths of chalcocite. Chalcopyrite and bornite have been recrystallised and locally remobilised during peak deformation and metamorphism and are commonly aligned parallel to cleavage and intergrown with, or overprinted by, silicate minerals.
  These generations are represented in both disseminations and veins of late diagenetic, syn-tectonic and late-tectonic origin. Croaker (2011) notes that whilst these relationships may be interpreted to indicate syn-orogenic introduction of metals, the existence of disseminated sulphides in more poorly deformed parts of the orebody that are truncated/overprinted by cleavage, is considered to be evidence of at least some pre-existing sulphide assemblages prior to deformation which was remobilised.
• Accessory sulphides - sphalerite occurs as anhedral grains within black carbonaceous shales, commonly on the margins of chalcopyrite grains aligned parallel to cleavage. Molybdenite occurs as rare 10 to 30µm subhedral grains, associated with veins parallel to and crosscutting cleavage, commonly intergrown with chalcopyrite and bornite.
• All mineralised veins are confined to the stratabound, folded copper orebody envelope and regardless of their generation, contain a similar sulphide and gangue assemblage to the host lithology.

Zonation of Ore Minerals
 There is a zonation of minerals, on both a deposit and local scale reflecting the paragenesis. At the deposit scale, there is a gross mineral zonation from hematite in oxidised footwall rocks to a chalcocite-bornite assemblage in immediately adjacent or overlying reduced rocks, particularly those adjacent to syn-sedimentary faults. The chalcocite-bornite assemblage then grades stratigraphically upward and/or laterally away from the footwall or syn-sedimentary structures, to a bornite-chalcopyrite assemblage, then a chalcopyrite-rich assemblage, a chalcopyrite-pyrite assemblage and, finally to pyrite (Hitzman et al., 2012). This zonation reflects the flow of Cu-bearing ore fluids, from chalcocite-bornite proximal to pyrite distal.
  On a finer scale, zonation may occur between individual beds, being relatively simple where host rocks lack significant compositional layering, to complex and overlapping where bedding is well developed (e.g., the Mines Subgroup orebodies), and fluids are contemporaneously penetrating along and outwards from closely spaced layers.
  Individual grains of sulphide may also display sequential, concentric replacement textures, mimicking the observed broader scale mineral zonation. Similarly, the transition from early to late-formed sulphides is reflected by identical zoning in disseminated sulphides, veins and nodules (Brummer, 1955; Mendelsohn, 1961; Richards et al., 1988; Selley et al., 2005; Sillitoe et al., 2010). The complex and overlapping mineral zonation observed in some deposits, particularly those of the Mines Subgroup in the DRC, could reflect either multiple fluid ingress events, controls on sulphide speciation by local host-rock variability, or both (Hitzman et al., 2012).
  The earliest stage pyrite may be formed during early diagnesesis in anaerobic tidal marsh conditions, from the reaction between iron oxides, organic matter and sea water sulphate, as follows:   Fe
2O3 + 4 SO42- + 8 CH2O + 0.5 O2 → 2 FeS2 + 8 HCO3- + 4 H2O (Fanning et al., 2012). Alternatively it may be formed from sour gas generated by the reaction between mobile hydrocarbons and authigenic anhydrite, as follows: CaSO4 + CH4 → CaCO3 + H2S + H2O. The H2S then reacts with iron oxide in the reservoir rocks in a two stage process to first produce the monsulphide FeS (Mackinawite): Fe2O3 + 3 H2S → 2 FeS + S + 3 H2O which then reacts further with H2S to produce the more stable pyrite: FeS + H2S = FeS2 + H2 (Schoonen, 2004). The two reactions tend to produce a different gangue. Reduction of seawater sulphide produces the weak carbonic acid, which may be flushed in the shallow aqueous conditions, while the production of H2S and then pyrite results in a carbonate gangue of dolomite as detailed below. These reactions represent the first stages of sulphide which are overprinted by copper sulphides as Cu-rich solutions infiltrate in situ reductant bed, or enter the mobile reductant reservoir. Early pyrite is preserved either as cores to later sulphides, or distal to both ore and the influx of Cu-rich solutions, where they are not replaced.
  Influx of an oxidised Cu-bearing brine, most likely with a chloride ligand, which is in equilibrium with footwall oxidised arenites, is reduced on contact with the reductant, decreasing the solubility of Cu, and resulting in its release from solution. This leads to the generation of chalcopyrite, either by addition of Cu to the lattice of existing pyrite, without additional sulphur: 2 FeS
2 + 2 CuCl + H2O → 2 CuFeS2 + 2 HCl + 0.5 O2, or by direct combination with iron oxide and H2S in the mobile reductant reservoir: Fe2O3 + 4 H2S + 2 CuCl → 2 CuFeS2 + 2 HCl + 3 H2O. The addition of further Cu progressively converts chalcopyrite into bornite, either by complete replacement, or as rims to a chalcopyrite (or pyrite) core, as follows: 4 CuFeS2 + 6 CuCl + 3 H2O → 2 Cu5FeS4 + 6 HCl + Fe2O3. While Cu-bearing brine remains, or continues to ingress, the bornite is progressively converted to chalcocite: 2 Cu5FeS4 + 6 CuCl + 3 H2O → 8 Cu2S + 6 HCl + Fe2O2.
  The zoning pattern and paragenesis suggests that after initial pyrite and early chalcopyrite deposition, the process of ore formation predominantly involved the addition of Cu to alter existing sulphides, with lesser new sulphur added to the assemblage.
  Each new generation of Cu sulphide with a progressively higher Cu:S ratio, begins to be generated from the last, at the interface between the incoming oxidised Cu-bearing brine in the oxidised arenites and the sulphide body, whilst sulphides with the lowest Cu:S ratio are distal, grading outward into barren pyrite. The above zoning pattern suggest the fluid influx was both from below and laterally from the syn-sedimentary structures, i.e., the fault structures were the conduits for the mineralising fluids, which were released into porous footwall arenites, and precipitated when reducing hydrocarbons were encountered, either within those arenites or an overlying aquitard.
  As indicated above (Reductants and redox boundaries section), the excess HCl produced by these processes may reverse or terminate the initial generation of H
2S, unless buffered by excess Fe, Mg or Mn ions which produces a gangue of dolomite, ferroan dolomite as excess Fe is released and magnesite.
  Borg et al. (2012) suggest that a similar process of sulphide formation and acid generation, promoted the dissolution of interstitial sulphate and carbonate cements in the Kupferschiefer of Europe, and increased permeability, allowing the progress of the mineralising front into cemented host rocks and ultimately the slow escape of depleted mineralised brines into the rocks above, permitting the influx of new brines from below.

Geochronology of ore
  Most datings of sulphides and ore-related minerals in the Zambian Copperbelt give Lufilian ages of 670 to 550 Ma. Available data from Selley et al. (2005) includes the following:
• Nchanga - 576±41 Ma (Re-Os Co sulphide; Barra and Broughton, unpub. data);
• Chibuluma West - 576±41 Ma (Re-Os Cu sulphide; Barra and Broughton, unpub. data);
• Nkana-Mindola - 520±20 Ma (U-Pb uraninite; Cahen et al.,1971 and references therein); 522±15 Ma (U-Pb uraninite; Darnley et al., 1961);
   576±41 Ma (Re-Os Cu sulphide; Barra and Broughton, unpub. data); 525±3.4 Ma (Re-Os molybdenite; Barra et al., 2004);
• Musoshi - 514±3 Ma (U-Pb uraninite; Richards et al., 1988); 514±2 Ma (U-Pb rutile; Richards et al., 1988); 496±1 Ma (U-Pb rutile; Richards
    et al., 1988); 645±15 Ma (Pb-Pb Cu sulphide; Richards et al., 1988);
• Kansanshi - 503±15 Ma (U-Pb uraninite; Darnley et al., 1961); 512.4±1.2 Ma (Re-Os molybdenite; Torrealday et al., 2000); 502.4±1.2 Ma
    (Re-Os molybdenite; Torrealday et al., 2000); 511±11Ma (U-Pb monazite; Torrealday et al., 2000).
However, an Re-Os isochron age for chalcopyrite in diagenetic evaporitic nodules in the hanging wall (not ore) of the Konkola deposit (Barra et al., 2004), yielded an age of 816±62 Ma presumed to be close to the post 877±11 Ma (basement Nchanga Red Granite age) depositional age. The minimum age of 645±15 Ma determined for copper-sulphides in little deformed disseminated ores from the Musoshi deposit, DRC (Richards et al., 1988) would be consistent with a late diagenetic emplacement. The range of dates, styles of mineralisation, textural evidence and the presence of ore in rocks younger than this earliest age, suggest mineralisation took place over a protracted period from late diagenesis to post orogenesis.

Basement Mineralisation
   Basement mineralisation is found in numerous locations within the Lufubu Complex gneisses, schists and granitoids, both in close association with, and distal to, Roan Group hosted deposits. Mineralisation occurs in a number of forms, specifically:
• within palaeosols/palaeoregolith formed at the Katangan unconformity, where Roan Group hosted orebodies rest directly onto basement topographic highs. This is interpreted to represent mineralising fluids that have penetrated into the weathered regolith during the main ore formation. In some localities this mineralisation persists below the regolith, e.g., at Mufulira, where deep fissures filled with Roan Group sands, pebbles and boulders contain disseminated pyrite and chalcopyrite. Similar mineralised palaeosols have been outlined at Nkana and Nchanga (Pienaar, in Mendelsohn, 1961).
• mineralised veins within basement below orebodies, e.g., at Luanshya, where the main orebody in the lower Roan Subgroup rests directly on basement, chalcopyrite and minor pyrite occurs in sporadic, short, discontinuous quartz-calcite veins and as disseminations within schist (mainly biotite schist). The overall average grade in the zone is ~1% Cu, over a thickness of 10 to 15 m below the unconformity. Similar mineralisation has been outlined at Nchanga in both the palaeosol and as dissemination and veins in the underlying granite to depths of ~8 m, carrying an average of 0.77% Cu. At Mufulira, pyrite and chalcopyrite occur in short, erratic and discontinuous quartz-carbonate veins which contain some anhydrite. The more persistent veins strike NE and dip to the NW. At the Selkirk shaft (Mufulira), mineralised veins up to 2 cm thick occur in swarms up to 400 m below the unconformity, hosted by both schists and granites (more abundant near granite contacts), with maximum grades of up to 3% Cu over 2 m intervals (Pienaar, in Mendelsohn, 1961).
• basement host deposits removed from Roan Group ores, the most significant of which is the Samba deposit, hosted in 1.9 Ga (Rainaud et al., 2005) basement metavolcanic rocks on the western edge of the Zambian Copperbelt, 21 km south of Chingola and 24 km west if Chambishi. Mineralisation is hosted by quartz-sericite to quartz-biotite and chloritic schists, which have gradational contacts with sandwiching granodioritic to quartz-monzonitic gneisses (Wakefield, 1978; Freeman, 1988). It occurs as disseminations, stringers and veinlets of pyrite, chalcopyrite and bornite, with minor shallow malachite development. The mineralisation forms lenses that dip at 45 to 80°S and vary from a few mm to ~10 m in thickness, usually decreasing in width with depth. Grades vary from trace to 2.16% Cu over 8.15 m widths, the best being 1.68 m of 4.11% Cu. Two or three, locally up to eight, bands are present at any one interval, each separated by waste bands that are from 2 to 140 m thick. Samba has been interpreted to be a Palaeoproterozoic porphyry Cu deposit with a resource of ~50 Mt @ 0.5% Cu (Wakefield 1978). Freeman (1988) quotes a resource of 14 Mt @ 1.1% Cu with a higher cut-off, based on the tabular bands of ore. However, Hitzman 2012, quotes unpublished data (M. Hitzman, unpub. data, 2006), which has demonstrated that mineralization took place between 490 and 460 Ma, during late to post Lufilian orogenesis.
   Another of the basement accumulations (undated) is the Fimpimpa Prospect, on the NE tip of the Kafue Anticline, 20 km NE of Nchanga and <10 km west of Lubembe, where copper mineralisation occurs along a massive quartz vein cutting basement garnetiferous quartz-mica schists and biotite gneisses, and in an adjacent, vermiculite-rich lamprophyre dyke (Freeman, 1988) or feldspathised quartz diorite (Pienaar, in Mendelsohn, 1961). The lamprophyre dyke is continuous for 20 km south to the Nchanga River Lode. The quartz vein is ~8 m thick with sporadic malachite, chalcopyrite and bornite and is largely < 0.4% Cu (Pienaar, in Mendelsohn, 1961). The lamprophyre dyke is host to fracture, quartz-calcite vein to veinlet hosted and disseminated malachite, chalcopyrite and bornite mineralisation over widths of up to 14 m. The known resource over a 1000 m interval tested was estimated at 1.2 Mt @ 1.23% Cu to a depth of 100 m, including 0.2 Mt @ 1.19% Cu as cupriferous mica to a depth of 15 m (Freeman, 1988).
   Most of the basement hosted occurrences below the palaeoweathering zone have been assumed to represent pre-Katangan mineralisation and illustrate the fertility of the basement as a source of metals. However, the dating of Samba questions this latter assumption. If other occurrences are shown to be Lufilian in age, they may instead reflect the passage of mineralised fluids upward into the Katangan sequence.

Timing, Origin and Discussion        This section is currently being added and is not yet complete

Based on the observations and interpretations outlined, and cited, throughout this summary and that of the Congolese/Katangan Copperbelt record, the following sequence of events and processes are proposed to explain the development of the Lufilian Arc and the ore deposits of the Central African Copperbelt in both Zambia and the DRC:

• Following basin inversion of the NW-SE trending Kibaran and Irumide rift systems, and amalgamation of the Rodinia Supercontinent, there was an ~100 to 200 Ma lull in tectonic activity in what is now southern and central Africa.

• After ~900 Ma, NE-SW directed extension began to the immediate SW of the main Kibaran-Irumide depocentres. This extension resulted in early, ~880 to 850 Ma bimodal volcanic activity and granitic intrusion in what is now the Zambezi Belt and possibly the southern Lufilian Arc, while in the main Zambian Copperbelt, no volcanic rocks and only limited granite intrusion is preserved (e.g., the ~880 Ma Nchanga Red Granite). This latter intrusive activity accompanied the uplift of a NNW-SSE elongated horst block or upwarp, that was to become the Kafue Anticline and form the core of the Zambian Copperbelt. Following intrusion, the horst/upwarp was eroded to expose the granites, prior to deposition of the basal Katanga Supergroup on its flanks.
  This early bimodal magmatism is characteristic of intra-continental rifting, taken to be the result of crustal thinning due to extensional attenuation, shallowing of the Moho, concomitant mantle upwelling, pooling and development of a thick mafic underplate, with consequent anatexis of the lower crust. The mafic volcanism comprises crustal contaminated mantle derived magma, while the felsic volcanism and intrusions are anatectic crustal melt material.

• Extension continued with the development of a number of NW-SE trending extensional fault controlled rift basins (grabens or half grabens), flanking the "Kafue Anticline" basement high, restricted to the Zambian Copperbelt area. These basins were filled with coarse, oxidised rift facies clastic sediments (Mindola Clastics Formation) of limited lateral extent. With progressive extension and subsidence, these became interconnected and grew into a larger rift basin, predominantly in Zambia. There is no convincing evidence of similar rocks in the Congolese Copperbelt.

• Deposition continued with the laterally more extensive Kitwe Formation, composed of clastic rocks, passing upward into dolomitic sediments within the main rift basin in Zambia. The upper dolomitic beds mark the waning of rifting and the onset of the sag phase.
  A 10 to 15 km wide corridor of argillaceous rocks of the Copperbelt Orebody Member occur at the base of the Kitwe Formation, fringing and lapping onto the western margin of the "Kafue Anticline" basement, capping the Mindola Clastics Formation, but lensing out into the basin to the west.
  The Copperbelt Orebody Member represents a transgressive event. It contains ample in situ hydrocarbons and early diagenetic, generally framboidal, pyrite disseminations and nodules, formed by bacterial sulphate reduction from sea water.

• The succeeding sag phase is represented by the Upper Roan Subgroup, dominantly composed of carbonate rocks, including the first interpreted evaporite unit, now represented by a breccia zone after total dissolution. These sag phase rocks spread onto basement, well beyond the margins of the main rift basin, particularly to the north and NE into the DRC, where salt/evaporite, carbonate and reefal units were developed in a lagoonal to shallow marine environment, forming the R.A.T., Mines and Dipeta subgroups of the DRC Roan Group.
  A stromatolitic reef formed in the Congolese Copperbelt area, possibly in part on a shallow rise marking the northward continuation of the "Kafue Anticline" basement high. This reef restricted sea water flow between the main marine basin to the SW, and the shallow embayment to its north and NE, between the Congo Craton and Bangweulu Block, and led to the concentration of hypersaline brines and the accumulation of a thick (>500 m) salt/evaporite bed in a lagoonal to sabkha setting. The R.A.T. Subgroup, is interpreted to be the clastic residue after dissolution of most of this salt/evaporite bed. The lagoonal to marine shelf Upper Roan Subgroup in Zambia was not restricted and consequently, the salt/evaporite unit was thinner, possibly disappearing to the SW.
  Following the oxidised R.A.T. Subgroup, the Mines Subgroup in the Congolese Copperbelt marked a transgressive event, and deepening of the basin over and north of the reef. It is largely composed of reduced rocks that, like the Copperbelt Orebody Member in Zambia, contain ample in situ hydrocarbons and early diagenetic, generally very fine grained pyrite disseminations and nodules, formed by bacterial sulphate reduction from sea water. The 10 to 30 m thick R.S.C. Member, originally largely composed of stromatolitic dolostones, occurs about 10 m above the base of the Mines Subgroup, overlain and underlain by laminated dolomitic shales that were deposited within a shallow-water, high-salinity, reducing, intertidal environment. These two laminated members were to become hosts to the main Lower and Upper orebodies, separated by barren, highly silica-dolomite altered R.S.C. in most of the Congolese Copperbelt orebodies.
  The Mines Subgroup is overlain by the Dipeta Subgroup, with the basal R.G.S. Member marking a regression and change to oxidised clastic and evaporitic conditions analogous to the R.A.T. Subgroup, before transgression and a return to reduced carbonatic and reduced rocks more similar to those of the Mines Subgroup.

• At some time following the deposition of the salt/evaporite unit within the Upper Roan Subgroup in Zambia, the Roan Group was subjected to regional calcic-magnesian alteration, in the form of diagenetic anhydrite, dolomite, calcite and quartz, mainly occurring as interstitial disseminations, replacements, veinlets and overgrowths throughout the Roan Group. This alteration is inferred to be related to the dissolution and redistribution of that evaporite bed by diagenetic brine reflux, a process whereby dense Mg-Ca-SO
4 brines, dissolveded from salt/evaporite beds, sink to displace lighter fresh pore waters in underlying units to precipitate the alteration minerals. It resulted in up to 30% authigenic anhydrite in large sections of the underlying Lower Roan Subgroup in Zambia, particularly within arenite beds of the Mindola Clastics and Kitwe formations.
  Early diagenetic celestite, gypsum and anhydrite nodules are similarly recorded in DRC deposits, while carbonate (mainly magnesite) crystal growth occurs in carbonate and argillaceous-carbonate rocks, and Mg-chlorite in more argillaceous rocks. This alteration is attributed to dissolution, circulation and redistribution of evaporite/salt beds in the the R.A.T. and R.G.S., into other parts of the Mines and Dipeta subgroups.

• The Upper Roan and Dipeta Subgroups, in Zambia and DRC respectively, are conformably overlain by the deeper water, predominantly black pyritic shales of the Mwashya (or Mwashia) Subgroup. During this period, the centre of deposition migrated northwards into the DRC, where the enviroment had previously been lagoonal to marine shelf. These shales are accompanied by 765 Ma mafic volcanism in the northwestern part of the basin in western Zambia and the northen half of the Congolese Copperbelt and herald the beginning of a renewed phase of extension.

• This major renewed extensional event began with the deposition of the Mwashya Subgroup and the overlying Nguba Group. It resulted in: i). deepening of the Katanga basin; ii). northward migration of the main centre of deposition; iii). expansion of the sequence onto Kibaran and Irumide basement on the basin margins and into the extensive Kundelungu Gulf Foreland; iv). development of a series of metamorphic core complexes to create the arcuate Domes Region in Zambia, updoming the Roan Group, and acting as basement highs to the Nguba and Kundelungu groups; v). a broad corridor of gabbroic intrusions (753 and 742 Ma from 2 datings) coincident with the Domes Region, from the Kafue Anticline to the Angola border; vi). an extensive regional 'volcanic belt' defined by thin mafic lavas and associated pyroclastic flows and volcaniclastic rocks interbedded with dolostones, extending from NW Zambia, following the Lufilian Arc to the central Congolese Copperbelt.
  Mafic intrusions cut rocks from the Lufubu Metamorphic Complex to the lower Nguba Group, but were preferentially emplaced as sills in the Upper Roan Subgroup. Mafic and lesser felsic lavas were intercalated in the western half of the basin in the Mwashya Subgroup and Grand Conglomérat. Over the period 765 to 735 Ma, extrusive mafic magmatism progressed from continental tholeiite in the Mwashya Subgroup, to alkaline and tholeiitic magmas, and finally to lavas with E-MORB affinities (i.e., a transition from crust-contaminated to less contaminated asthenoshpheric melt) in the Nguba Group Grand Conglomérat Formation diamictite sequence. This extension resulted in additional crustal attenuation, further shallowing of the Moho, large scale mafic pooling in the lower crust, the release of considerable energy, and an increase in the thermal gradient. Although mafic magmatism was widespread, felsic equivalents are rare. This may be because the less readily melted mafic underplate from the first extension insulated the felsic crust from appreciable anatectic melting by the upwelling asthenosphere, but still allowed differentiation and ingestion of crustal material to produce sufficiently bouyant magma that could rise and form the intrusive and volcanic rocks observed.

• Following the Grand Conglomérat, deposition continued with the remainder of the Nguba Group, starting with the Kakontwe Limestones, which are best developed around the Domes in Zambia, followed by dolomitic arkosic siltstones, shales, sandy shales and sandstones and the overlying Kundelungu Group, the base of which is represented by the Petit Conglomérat Formation, that has been correlated with the global 635 Ma Marinoan glaciogenic event.

• At some stage following deposition of the Roan Group, most likely during Nguba Group sedimentation, mobile hydrocarbons were generated and migrated up-dip or up-structure (faults), into stratigraphic or structural traps below a number of aquitards within the Roan Group, including argillaceous interbeds within the Mindola Clastics Formation, the Copperbelt Orebody Member, argillaceous beds within the Mufulira ore-bearing sandstone, argillaceous beds higher in the Kitwe Formation, and the Mwashya Subgroup shales.
  The stratabound copper sulphide deposits of the Roan Group in Zambia are almost invariably located within or immediately above, these stratigraphic or structural features that could trap migrating fluids, and which in most cases, contain (or can be inferred to have contained) a mobile hydrocarbon. These trap sites are dominantly, but not universally, where the fine grained cap rocks/aquitards listed above, overstep thinning wedges of underlying oxidised arenite, to lap, up-dip, onto basement, usually coinciding with syndepositional growth faults. Ore occurs either immediately below the cap rock, or within it, or both.
  As outlined in the Reductants and Redox Boundaries section above, at a normal thermal gradient, mobile hydrocarbons are produced by the maturation of organic-rich sedimentary rocks, when they pass through the oil window at depths of 2 to 4 km and the gas window from 3 to 6 km, representing temperature ranges of ~60 to 120°C and ~100 to >200°C respectively, in the absence of other heat sources.
  Potential source rocks containing sufficient organic matter include the Copperbelt Orebody Member, the Mwashya shale, other reduced facies that may be buried in the core of the Katanga Basin, and carbonaceous argillites at the top of the Irumide and Kibaran sequences. Most of these units would need to have been structurally displaced to a lower level during the renewed rift extension so that the hydrocarbons generated could migrate upwards to trap sites that are mostly in the Lower Roan Subgroup.
  Except for the Kibaran-Irumide rocks, a sufficient burden of overlying rocks alone would not have been reached until deposition of the Kundelungu Group, immediately prior to basin inversion with the onset of the Lufilian Orogeny deformation. However, the shallowing of the Moho and the injection of mafic magmatism during both the initial and renewed extension would have raised the thermal gradient, particularly the sill like gabbro bodies preferentially emplaced in the Upper Roan Subgroup, between the potential source rocks of the Copperbelt Orebody Member and the Mwashya shales. This additional energy input would have decreased the depth of burial required to achieve the oil and gas windows temperature ranges.
  By the time the source rocks within the core of the basin (not necessarily those at the site of the potential ore zones on the shallower basin margin) had been buried to the necessary depths, lithification would have been well advanced, and the hydrocarbons generated and emplaced during late diagnesis. The reservoir rocks would have not only intertstitial pore space porosity, but also brittle fractures. The hydrocarbons would have to be emplaced before the permeability of the reservoir rocks was occluded by cements and advanced lithification. The preservation of permeability in this type of sedimentary sequence/setting is common, e.g., the Permian sandstones that host and form the footwall to the Kupferschiefer ores in Europe, also host petroleum reservoirs in Poland and the major North Sea oil fields, and are still both permeable and porous, allowing hydrocarbons to be extracted, almost 300 m.y. after deposition. Formation of mobile hydrocarbons is known to occur within lithologies of this age elsewhere, as evidenced by petroleum bleeds into deep oil wells cutting the temporally, lithologically and tectonically comparable succession in the Amadeus Basin of Central Australia (Marshall et al., 2007).
  Alternatively, Selley et al. (2005) explore the possibiility that the restriction of arenite-hosted deposits to within a 200 m thick fringe straddling the in situ hydrocarbon bearing Copperbelt Orebody Member, suggest that unit may have been a major source of mobile hydrocarbons that were released along the lower and upper boundary of the unit, and directed laterally through permeable media or vertically along fracture zones toward physical traps without substantial basinal migration. However, to do so, the ore-bearing section of the basin would have to go through the oil and/or gas window. This may well be the case, as fluid inclusion homogenisation temperatures of 110 to 170°C are quoted for diagenetic early chalcopyrite-bearing mineralisation replacing carbonate nodules at Chambishi by Annels (1989).

• Following emplacement of mobile hydrocarbons into Roan Group reservoirs, it reacted with the authigenic anhydrite precipitated during the earlier diagenetic calcic-magnesian alteration to produce H
2S, which in turn reduced hematite within the oxidised arenites of the reservoir to produce pyrite. See the Zonation of Ore Minerals section for the chemical reactions.
  This late diagenetic 'early' pyrite preceded Cu mineralisation. It is younger than the early diagnetic 'early' pyrite of the argillaceous hosts produced soon after deposition of each of the main units containing in situ hydrocarbons, specifically, the Copperbelt Orebody Member (Lower Roan Subgroup), the Mwashya Subgroup and Grand Conglomérat (Nguba Group). As such, formation of 'early' pyrite took place on a number of different occassions in different parts of the basin.
  The pyrite associated with in situ hydrocarbons also preceded Cu mineralisation, and although overlapping subsequent ore zones is often much more laterally extensive, and may occur without any associate ore. However, because of its dependence upon trap sites, mobile hydrocarbons and associated pyrite are often less extensive.
  The role of mobile hydrocarbons within the Mines Subgroup in the Congolese Copperbelt is uncertain, as most hydrocarbons there appear to be in situ. The protential reservoir rock, the R.S.C. Member is generally barren of any primary sulphides, which are restricted to the laminated dolomitic shales of the adjacent Lower and Upper orebody hosts which would appear to be the result of early diagenesis.

The most recent source geological information used to prepare this summary was dated: 2012.     Record last updated: 13/1/2015
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd.   Unauthorised copying, reproduction, storage or dissemination prohibited.

  References & Additional Information
 References to this deposit in the PGC Literature Service Collection: Want any of these papers ? Click Here
Annels A E  1989 - Ore Genesis in the Zambian Copperbelt, with Particular Reference to the Northern Sector of the Chambishi Basin: in Boyle R W, Brown A C, Jefferson C W, Jowett E C, Kirkham R V, (eds),  Sediment-hosted Stratiform Copper Deposits:  Geological Association of Canada   Special paper 36 pp 427-452
Annels A E  1984 - The Geotectonic Environment of Zambian Copper-cobalt Mineralization: in    Journal of the Geological Society of London   v141 pp 279-289
Annels A E  1974 - Some Aspects of the Stratiform Ore Deposits of the Zambian Copperbelt and their Genetic Significance: in Bartholome P (Ed),  Gisements Stratiformes et Provinces Cupriferes: Societe Geologique de Belgique, Liege    pp 235-254
Annels A E,  1979 - Mufulira Greywackes and Their Associated Sulphides: in    Trans. IMM, Section B   v.88 pp B15-B23
Annels A E, Vaughan D J, Craig J R  1983 - Conditions of Ore Mineral Formation in Certain Zambian Copperbelt deposits with Special Reference to the Role of Cobalt: in    Mineralium Deposita   v18 pp 71-88
Armstrong R A, Master S and Robb L J,  2005 - Geochronology of the Nchanga Granite, and constraints on the maximum age of the Katanga Supergroup, Zambian Copperbelt: in    J. of African Earth Sciences   v42 pp 32-40
Armstrong R A, Robb L J, Master S, Kruger F J, Mumba P A C C  1999 - New U-Pb age constraints on the Katangan Sequence, Central African Copperbelt: in    Journal of African Earth Sciences, Elsevier, Amsterdam   v28, no.4A pp 6-7
Brandt R T, Burton C C J, Maree S C, Woakes M E  1961 - Mufulira: in Mendelsohn F (ed),  Geology of the Northern Rhodesian Copperbelt McDonald, London    pp 411-461
Bull S, Selley D, Broughton D, Hitzman M, Cailteux J, Large R and McGoldrick,  2011 - Sequence and carbon isotopic stratigraphy of the Neoproterozoic Roan Group strata of the Zambian copperbelt: in    Precambrian Research   v.190 pp. 70-89
Cailteux J L H, Kampunzu A B and Lerouge C,  2007 - The Neoproterozoic Mwashya-Kansuki sedimentary rock succession in the central African Copperbelt, its Cu-Co mineralisation, and regional correlations: in    Gondwana Research   v.11 pp. 414-431
Cailteux J L H, Kampunzu A B, Lerouge C, Kaputo A K and Milesi J P,  2005 - Genesis of sediment-hosted stratiform copper-cobalt deposits, Central African Copperbelt: in    J. of African Earth Sciences   v42 pp 134-158
Daly M C, Chakraborty S K, Kasolo P, Musiwa M, Mumba P. Naidu B, Namateba C, Ngambi O, Coward M P  1984 - The Lufilian Arc and Irumide Belt of Zambia, Results of a Geotraverse across their Intersection: in    Journal of African Earth Sciences, Elsevier, Amsterdam   v2, no.4 pp 311-318
Darnley A G  1960 - Petrology of Some Rhodesian Copperbelt Orebodies and Associated Rocks: in    Transactions of the Institution of Mining and Metallurgy   v69 pp 137-173
Ellis M W, Austen A L, Garlick W G, Gane P G, Cornwall F W  1961 - Exploration: in Mendelsohn F (ed),   Geology of the Northern Rhodesian Copperbelt McDonald, London    pp 166-212
Fleischer V D  1984 - Discovery, Geology and Genesis of Copper-cobalt Mineralisation at Chambishi Southeast Prospect, Zambia: in    Precambrian Research    v25, no.1-3 pp 119-133
Fleischer V D, Garlick W G, Haldane R  1976 - Geology of the Zambian Copperbelt - (Excerpt on Genesis): in Wolf K H, (ed),  Handbook of Strata-bound and Stratiform Deposits; II. Regional Studies and Specific Deposits Elsevier, Amsterdam   v6, Cu, Zn, Pb and Ag Deposits pp 323-352
Fleischer V D, Garlick W G, Haldane R  1976 - Geology of the Zambian Copperbelt (Exerpt covering Roan Antelope and Baluba): in Wolf K H, (ed),  Handbook of Strata-bound and Stratiform Deposits; II. Regional Studies and Specific Deposits Elsevier, Amsterdam   v6, Cu, Zn, Pb and Ag Deposits pp 285-297
Fleischer V D, Garlick W G, Haldane R  1976 - Geology of the Zambian Copperbelt - Mufulira Mine, Zambia (Exerpt on Mufulira only): in Wolf K H, (ed),  Handbook of Strata-bound and Stratiform Deposits; II. Regional Studies and Specific Deposits Elsevier, Amsterdam   v6, Cu, Zn, Pb and Ag Deposits pp 304-323
Fleischer V D, Garlick W G, Haldane R  1976 - Geology of the Zambian Copperbelt (Exerpt covering Nkana): in Wolf K H, (ed),  Handbook of Strata-bound and Stratiform Deposits; II. Regional Studies and Specific Deposits Elsevier, Amsterdam   v6, Cu, Zn, Pb and Ag Deposits pp 275-285
Fleischer V D, Garlick W G, Haldane R  1976 - Geology of the Zambian Copperbelt (Excerpt covering Konkola and Musoshi): in Wolf K H, (ed),  Handbook of Strata-bound and Stratiform Deposits; II. Regional Studies and Specific Deposits Elsevier, Amsterdam   v6, Cu, Zn, Pb and Ag Deposits pp 244-249
Fleischer V D, Garlick W G, Haldane R  1976 - Geology of the Zambian Copperbelt (Exerpt covering Chibuluma and Chibuluma West): in Wolf K H, (ed),  Handbook of Strata-bound and Stratiform Deposits; II. Regional Studies and Specific Deposits Elsevier, Amsterdam   v6, Cu, Zn, Pb and Ag Deposits pp 298-304
Fleischer V D, Garlick W G, Haldane R  1976 - Geology of the Zambian Copperbelt (Exerpt covering Chambishi): in Wolf K H, (ed),  Handbook of Strata-bound and Stratiform Deposits; II. Regional Studies and Specific Deposits Elsevier, Amsterdam   v6, Cu, Zn, Pb and Ag Deposits pp 249-256
Fleischer V D, Garlick W G, Haldane R  1976 - Geology of the Zambian Copperbelt (Excerpt covering the geology only): in Wolf K H, (ed),  Handbook of Strata-bound and Stratiform Deposits; II. Regional Studies and Specific Deposits Elsevier, Amsterdam   v6, Cu, Zn, Pb and Ag Deposits pp 223-243
Fleischer V D, Garlick W G,and Haldane R  1976 - Geology of the Zambian Copperbelt (Exerpt by Garlick and Haldane covering Nchanga): in Wolf K H, (ed),  Handbook of Strata-bound and Stratiform Deposits; II. Regional Studies and Specific Deposits Elsevier, Amsterdam   v6, Cu, Zn, Pb and Ag Deposits pp 256-274
Garlick W G  1961 - Chambishi: in Mendelsohn F (ed),  Geology of the Northern Rhodesian Copperbelt McDonald, London    pp 281-297
Greyling L N, Robb L J, Master S, Boiron M C and Yao Y,  2005 - The nature of early basinal fluids in the Zambian Copperbelt: A case study from the Chambishi deposit: in    J. of African Earth Sciences   v42 pp 159-172
Gunning H C  1961 - The Early Years: in Mendelsohn F (ed),  Geology of the Northern Rhodesian Copperbelt McDonald, London    pp 3-10
Haynes D W  1986 - Stratiform Copper deposits hosted by low-energy sediments: I. Timing of Sulfide precipitation - an hypothesis: in    Econ. Geol.   v81 pp 250-265
Haynes D W  1986 - Stratiform Copper deposits hosted by low-energy sediments: II. Nature of source rocks and composition of metal-transporting water: in    Econ. Geol.   v81 pp 266-280
Hitzman M W  1998 - Petrographic Studies of Ore Shale from the Zambian Copperbelt, Implications for Models of Ore Formation: in   Geological Society of America, 1998 Annual Meeting Geological Society of America - Abstracts with Programs   v30, No.7 pp 19-20
Hitzman M W, Selley D and Bull S,  2010 - Formation of Sedimentary Rock-Hosted Stratiform Copper Deposits through Earth History : in    Econ. Geol.   v105 pp 627639
Hitzman M W, Broughton D, Selley D, Woodhead J, Wood D and Bull S,  2012 - The Central African Copperbelt: Diverse Stratigraphic, Structural, and Temporal Settings in the Worlds Largest Sedimentary Copper District: in Hedenquist J W, Harris M and Camus F, 2012 Geology and Genesis of Major Copper Deposits and Districts of the World - A tribute to Richard H Sillitoe Society of Economic Geologists   Special Publication 16, pp. 487514
Hitzman M W, Kirkham R, Broughton D, Thorson J and Selley D,  2005 - The sediment-hosted stratiform copper ore system: in Hedenquist J W, Thompson J F H, Goldfarb R J and Richards J P (Eds.), 2005 Economic Geology 100th Anniversary Volume, Society of Economic Geologists, Denver,     pp. 609-642
Jordaan J  1961 - Nkana: in Mendelsohn F (ed),  Geology of the Northern Rhodesian Copperbelt McDonald, London    pp 297-328
Kampunzu A B and Cailteux J L H,  1999 - Tectonic Evolution of the Lufilian Arc (Central Africa Copper Belt) During Neoproterozoic Pan African Orogenesis: in    Gondwana Research   v.2 pp. 401-421
Key R M, Liyungu A K, Njamu F M, Somwe V, Banda J, Mosley P N and Armstrong R A,  2001 - The western arm of the Lufilian Arc in NW Zambia and its potential for copper mineralization: in    J. of African Earth Sciences   v.33 pp. 503528
Master S, Rainaud C, Armstrong R A, Phillips D and Robb L J,  2005 - Provenance ages of the Neoproterozoic Katanga Supergroup (Central African Copperbelt), with implications for basin evolution: in    J. of African Earth Sciences   v42 pp 41-60
Master S, Rainaud C, Armstrong R A, Philips D and Robb L J,  2005 - Provenance ages of the Neoproterozoic Katanga Supergroup (Central African Copperbelt), with implications for basin evolution: in    J. of African Earth Sciences   v.42 pp. 41-60
McGowan R  2001 - Towards a New Genetic Model for Precambrian Sediment-hosted Copper Deposits: in   A brief overview of the Zambian Copperbelt  - Web page extract, from: www.soc.soton.ac.uk/SOES/STAFF/sr1/Ross/RMcGowan_HP.htm    5p
McKinnon D, Smit N J  1961 - Nchanga: in Mendelsohn F (ed),  Geology of the Northern Rhodesian Copperbelt McDonald, London    pp 234-275
Mendelsohn F  1989 - Central/Southern African Ore Shale Deposits: in Boyle R W, Brown A C, Jefferson C W, Jowett E C, Kirkham R V, (eds),  Sediment-hosted Stratiform Copper Deposits Geological Association of Canada   Special paper 36 pp 453-469
Mendelsohn F  1961 - Roan Antelope: in Mendelsohn F (ed),  Geology of the Northern Rhodesian Copperbelt McDonald, London    pp 351-405
Mendelsohn F, Garlick W G, Pienaar P J, Demesmaeker G  1961 - General Geology (Extract): in Mendelsohn F (Ed.),  Geology of the Northern Rhodesian Copperbelt McDonald, London    pp 17-56
Porada H and Berhorst V,  2000 - Towards a new understanding of the Neoproterozoic-Early Palaeozoic Lufilian and northern Zambezi Belts in Zambia and the Democratic Republic of Congo: in    J. of African Earth Sciences   v.30 pp. 727-771
Porada H and Druschel G,  2010 - Evidence for participation of microbial mats in the deposition of the siliciclastic ore formation in the Copperbelt of Zambia: in    J. of African Earth Sciences   v.58 pp. 427-444
Rainaud C, Master S, Armstrong R A and Robb L J,  2005 - Geochronology and nature of the Palaeoproterozoic basement in the Central African Copperbelt (Zambia and the Democratic Republic of Congo), with regional implications: in    J. of African Earth Sciences   v.42 pp. 1-31
Rainaud C, Master S, Armstrong R A and Robb L J,  2003 - A cryptic Mesoarchaean terrane in the basement to the Central African Copperbelt: in    Journal of the Geological Society, London   v.160 pp 11-14
Rainaud C, Master S, Armstrong R A, Phillips D and Robb L J,  2005 - Monazite U-Pb dating and 40Ar-39Ar thermochronology of metamorphic events in the Central African Copperbelt during the Pan-African Lufilian Orogeny: in    J. of African Earth Sciences   v.42 pp. 183-199
Richards J P, Cumming G L, Krstic D, Wagner P A, Spooner E T C  1988 - Pb isotope constraints on the age of Sulfide ore deposition and U-Pb age of late Uraninite veining at the Musoshi stratiform Copper deposit, central African Copper belt, Zaire: in    Econ. Geol.   v83 pp 724-741
Richards J P, Krogh T E, Spooner E T C  1988 - Fluid inclusion characteristics and U-Pb Rutile age of late hydrothermal alteration and veining at the Musoshi stratiform copper deposit, central African Copper belt, Zaire: in    Econ. Geol.   v83 pp 118-139
Selley D, Broughton D, Scott R, Hitzman M, Bull S, Large R, McGoldrick P, Croaker M and Pollington N,  2005 - A new look at the geology of the Zambian Copperbelt: in   Economic Geology, 100 Anniversary Volume, Society of Economic Geologists,    pp. 965-1000
Sillitoe R H, Perello J and Garcia A,  2010 - Sulfide-Bearing Veinlets Throughout the Stratiform Mineralization of the Central African Copperbelt: Temporal and Genetic Implications : in    Econ. Geol.   v105 pp 1361-1368
Sutton S J and Maynard J B,  2005 - A fluid mixing model for copper mineralization at Konkola North, Zambian Copperbelt: in    J. of African Earth Sciences   v42 pp 95-118
Sweeney M A, Binda P L  1994 - Some Constraints on the Formation of the Zambian Copperbelt Deposits: in    J. of African Earth Sciences   v19 pp 303-313
Sweeney M A, Binda P L  1989 - The Role of Diagenesis in the Formation of the Konkola Cu-Co Orebody of the Zambian Copperbelt: in Boyle R W, Brown A C, Jefferson C W, Jowett E C, Kirkham R V, (eds),  Sediment-hosted Stratiform Copper Deposits Geological Association of Canada   Special paper 36 pp 499-518
Sweeney M A, Binda P L, Vaughan D J  1991 - Genesis of the Ores of the Zambian Copperbelt: in    Ore Geology Reviews   v6 pp 51-76
Sweeney M, Turner P, Vaughan D J  1986 - Stable isotope and geochemical studies of the role of early diagenesis in ore formation, Konkola Basin, Zambian Copper belt: in    Econ. Geol.   v81 pp 1838-1852
Unrug R  1988 - Mineralization Controls and Source of Metals in the Lufilian Fold Belt, Shaba (Zaire), Zambia and Angola: in    Econ. Geol.   v83 pp 1247-1258
Unrug R  1989 - LANDSAT-based Structural Map of the Lufilian Fold Belt and the Kundelungu Aulacogen, Shaba (Zaire), Zambia and Angola, and the Regional Position of Cu, Co, U, Au, Zn and Pb Mineralisation: in Boyle R W, Brown A C, Jefferson C W, Jowett E C, Kirkham R V, (eds),  Sediment-hosted Stratiform Copper Deposits Geological Association of Canada   Special paper 36 pp 519-524
Unrug R  1988 - Mineralization controls and source of metals in the Lufilian Fold Belt, Shaba (Zaire), Zambia, and Angola: in    Econ. Geol.   v83 pp 1247-1258
van Eden J G  1974 - Deposition and Diagenetic Environment Related to Sulfide Mineralization, Mufulira, Zambia: in    Econ. Geol.   v69 pp 59-79
Wendorff M,  2005 - Sedimentary genesis and lithostratigraphy of Neoproterozoic megabreccia from Mufulira, Copperbelt of Zambia: in    J. of African Earth Sciences   v42 pp 61-81
Winfield O  1961 - Chibuluma: in Mendelsohn F (ed),  Geology of the Northern Rhodesian Copperbelt McDonald, London    pp 328-342
Zientek M L, Hayes T S and Hammarstrom J M  2013 - Overview of a New Descriptive Model for Sediment- Hosted Stratabound Copper Deposits: in Zientek M L, Hammarstrom J M and Johnson K M, 2013 Descriptive Models, Grade-Tonnage Relations, and Databases for the Assessment of Sediment-Hosted Copper DepositsWith Emphasis on Deposits in the Central African Copperbelt, Democratic Republic of the Congo and Zambia USGS Scientific Investigations,   Report 20105090J pp. 2-16

 PGC Literature Compilations containing papers referring to this deposit: Browse & Buy collection papers
Africa-B 2001: Volume 1 - The Zambian Copper Belt

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