A New Look at the Geology of the Zambian Copperbelt

Selley, D; Broughton, David; Scott, Robert B.; Hitzman, Murray W.; Bull, SW; Large, Ross R.; McGoldrick, Peter; Croaker, Mawson; Pollington, Nicky; Barra, Fernando

doi:10.5382/av100.29

Cited by 100 publications

(106 citation statements)

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“…1B). The sedimentology, interpreted origins and stratigraphic architecture of diamictites and associated facies at Kamoa all support sedimentation in variablyconnected and progressively evolving rift subbasins (grabens or half grabens) not in a single large open basin, as interpreted for the Roan Group in Zambia and the Democratic Republic of Congo (Selley et al, 2005;Batumike et al, 2007). The Mwashya Subgroup has been attributed to an early phase of rifting (the so-called 'Roan Rift') separate from later rifting that produced the Grand Conglom erat and other Nguba Group strata .…”

Section: Regional Tectonic Settingmentioning

confidence: 66%

Basinal setting and origin of thick (1·8 km) mass‐flow dominated Grand Conglomérat diamictites, Kamoa, Democratic Republic of Congo: Resolving climate and tectonic controls during Neoproterozoic glaciations

2018

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The Kamoa sub‐basin, in the south‐eastern part of the Democratic Republic of Congo, is a rift basin that hosts a world‐class stratiform copper deposit at the base of a very thick (1·8 km) succession of matrix‐supported conglomerates (diamictite) (Grand Conglomérat Formation) that has been interpreted by some as the product of deposition in the aftermath of a planet‐wide glaciation. Newly available subsurface data consisting of more than 300 km of drill core throws new light on the origin of diamictite and associated facies types, and their tectonic, basinal and palaeoclimatic setting. Initiation of rifting is recorded by a lowermost subaqueous succession of fault‐related mass flow conglomerates and breccias (the ‘Poudingue’) with interdigitating coeval and succeeding sandstone turbidites (Mwashya Subgroup). Overlying diamictites of the Grand Conglomérat were deposited as subaqueous debrites produced by mixing and homogenization of antecedent breccias and gravel from the Poudingue and Mwashya sediments with basinal muds. Failure of over‐steepened basin margins and debris flow was likely to be triggered by faulting and seismic activity, and was accompanied by syn‐depositional subaqueous basaltic magmatism recorded by peperites and pillow lavas within diamictites. The thickness of diamictites reflects recurring phases of faulting, volcanism and rapid subsidence allowing continued accommodation of rapidly deposited resedimented facies well below wave base. A distal or indirect, glacial influence in the form of rare dropstones and striated clasts is evident, but tectonically‐driven mass flow destroyed any primary record of glacial climate originally present in basin margin sediments. Such basin margin settings were common during Rodinia rifting and their stratigraphy and facies record a dominant tectonic, rather than climatic, control on sedimentation. Deposition occurred on tectonic timescales inconsistent with a Snowball Earth model for Neoproterozoic diamictites involving a direct glacial contribution to deposition.

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Section: Regional Tectonic Settingmentioning

confidence: 66%

Basinal setting and origin of thick (1·8 km) mass‐flow dominated Grand Conglomérat diamictites, Kamoa, Democratic Republic of Congo: Resolving climate and tectonic controls during Neoproterozoic glaciations

2018

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“…Similar lithologies and textures within the Roan Group breccia of the Central Aftrican Copperbelt also suggest an origin as a former layered evaporite sequence (e.g. Jackson et al, 2003;Selley et al, 2005;Bull et al, 2011). Currently, there is a consensus among investigators that most of the diapiric breccia throughout the Flinders Ranges represents passive diapirs that grew at or just beneath the ground surface or sea floor due to an intricate balance between salt-supply rates and sediment-accumulation rates (e.g.…”

Section: Callanna Group Brecciamentioning

confidence: 94%

Geology and tectonics of Neoproterozoic salt diapirs and salt sheets in the eastern Willouran Ranges, South Australia

et al. 2014

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Allochthonous salt structures and associated primary and secondary minibasins are exposed in Neoproterozoic strata of the eastern Willouran Ranges, South Australia. Detailed geologic mapping using high-quality airborne hyperspectral remote-sensing data and satellite imagery, combined with a qualitative structural restoration, are used to elucidate the evolution of this complex, long-lived (>250 Myr) salt system. Field observations and interpretations at a resolution unobtainable from seismic or well data provide a means to test published models of allochthonous salt emplacement and associated salt-sediment interaction derived from subsurface data in the northern Gulf of Mexico. Salt diapirs and sheets are represented by megabreccias of nonevaporite lithologies that were originally interbedded with evaporites that have been dissolved and/or altered. Passive diapirism began shortly after deposition of the Callanna Group layered evaporite sequence. A primary basin containing an expulsion-rollover structure and megaflap is flanked by two vertical diapirs. Salt flowed laterally from the diapirs to form a complex, multi-level canopy, now partly welded, containing an encapsulated minibasin and capped by suprasalt basins. Salt and minibasin geometries were modified during the Late Cambrian-Ordovician Delamerian Orogeny (ca. 500 Ma). Small-scale structures such as subsalt shear zones, fractured or mixed 'rubble zones' and thrust imbricates are absent beneath allochthonous salt and welds in the eastern Willouran Ranges. Instead, either undeformed strata or halokinetic drape folds that include preserved diapir roof strata are found directly below the transition from steep diapirs to salt sheets. Allochthonous salt first broke through the diapir roofs and then flowed laterally, resulting in variable preservation of the subsalt drape folds. Lateral salt emplacement was presumably on roof-edge thrusts or, because of the shallow depositional environment, via open-toed advance or extrusive advance, but without associated subsalt deformation.

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“…Recently, some workers suggested the Lufilian Foreland as the fifth tectonic zone (Porada & Berhorst, 2000;Wendorff, 2005;Wendorff & Key, 2009). The Congolese Copperbelt (CCB) and the ZCB occur within the external fold and thrust belt and the Domes region, respectively ( Figure 1b; Bull et al, 2011;El Desouky et al, 2010;Selley et al, 2005). The ZCB was divided into the western and eastern Kafue Anticline by the exhumed basement core complex (Figure 2).…”

Section: Geological Settingmentioning

confidence: 99%

“…at Kamaoto and Konkola, respectively (Muchez, André-Mayer, Desouky, & Reisberg, 2015;Selley et al, 2005). This provided a minimum age constraint for the Lower Roan Group ore host.…”

Section: Deposition Age Of the Lower Roan Groupmentioning

confidence: 99%

“…. Most of the Cu deposits are hosted in the Copper Orebelt Member (COM) of the Lower Roan Group of the Katanga Supergroup (Selley et al, 2005). Therefore, systematic studies on the deposition ages and provenance of sedimentary rocks of the Lower Roan Group not only help to clarify the regional tectonic evolution but also to better understand the ZCB stratiform deposits and thereby guide future exploration work.…”

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confidence: 99%

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Detrital zircon U–Pb geochronology and provenance of the Neoproterozoic Lower Roan Group, Chambishi Basin, North‐eastern Zambia: Implication for rift evolution of the Congo Craton

et al. 2019

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Zambia Copperbelt hosts numerous world‐class, high‐grade sediment‐hosted stratiform Cu deposits. The Lower Roan Group of the Katanga Supergroup is the main ore host and mainly comprises clastic rocks. In this study, we conducted laser ablation inductively coupled plasma mass spectrometry detrital zircon dating on the sedimentary rocks of the Lower Roan Group in the Chambishi Basin, in order to investigate the Neoproterozoic rift evolution of the Congo Craton. Our results reveal that the main zircon age population (97.1%) falls within 2.1–1.7 Ga (peaks at 1.95 and 1.88 Ga), and minor age populations fall into the Archaean (2.7–2.4 Ga), Palaeoproterozoic (2.3–2.1 Ga), and Mesoproterozoic (1.5–1.05 Ga). Detrital zircons from the Lower Roan Group have distinct oscillatory zoning in cathodoluminescence images, high Th/U ratios (mostly 0.5–2.0), and are sub‐angular, suggesting close detrital provenance. Provenance of the Lower Roan group may have been mainly the Lufubu Metamorphic Complex, Bangweulu Block, and Muva Supergroup, and minor the nearby granitoids of the Irumide Belt. The south‐eastern Congo Craton likely underwent two Neoproterozoic rifting events: the first rift cycle lasted from 880 to 820 Ma when the Lower Roan and Upper Roan groups were deposited in the Roan Basin. After an uplift, the Mwashia, Nguba, and Kundelungu groups of the Katanga Supergroup were likely deposited during the second rift basin development (765–635 Ma). The similar detrital zircon age spectra suggested that the Mwashia Group may have derived from the Lower Roan Group.

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A New Look at the Geology of the Zambian Copperbelt

Cited by 100 publications

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Basinal setting and origin of thick (1·8 km) mass‐flow dominated Grand Conglomérat diamictites, Kamoa, Democratic Republic of Congo: Resolving climate and tectonic controls during Neoproterozoic glaciations

Basinal setting and origin of thick (1·8 km) mass‐flow dominated Grand Conglomérat diamictites, Kamoa, Democratic Republic of Congo: Resolving climate and tectonic controls during Neoproterozoic glaciations

Geology and tectonics of Neoproterozoic salt diapirs and salt sheets in the eastern Willouran Ranges, South Australia

Detrital zircon U–Pb geochronology and provenance of the Neoproterozoic Lower Roan Group, Chambishi Basin, North‐eastern Zambia: Implication for rift evolution of the Congo Craton

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