The Kibaran of southern Africa: Tectonic evolution and metallogeny

Thomas, Robert J.; Agenbacht, A.L.D.; Cornell, David H.; Moore, John M.

doi:10.1016/0169-1368(94)90025-6

Cited by 152 publications

(54 citation statements)

References 45 publications

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“…Figures 4 and 6 in Thomas et al, 1994). However, the regional tectonic fabric imaged in profile IyA-200501 dips north and the shallow dipping décollement separating the mid-and lower crust is not a deep suture.…”

Section: Mesoproterozoic Tectonic Settingmentioning

confidence: 99%

“…Moore et al, 1986;Sangster et al, 1992;Thomas et al, 1994;Robb et al, 1999). However, no geophysical comparisons have been made because until recently, no complementary seismic profiles have been available.…”

Section: Rodinian Connectionsmentioning

confidence: 99%

“…Hartnady et al, 1985;Joubert, 1986a, b;Cornell et al, 1992;2006;Gibson et al, 1996;Thomas et al, 1994;1996;Basson and Watkeys, 2003;Colliston and Schoch, 2002;Eglington and Armstrong, 2003;Raith et al, 2003;Eglington, 2006;Bailie et al, 2007;Cornell and Pettersson, 2007 and references therein).…”

Section: Mesoproterozoic Tectonic Settingmentioning

confidence: 99%

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Deep Crustal Profile Across the Southern Karoo Basin and Beattie Magnetic Anomaly, South Africa: An Integrated Interpretation With Tectonic Implications

Lindeque

Wit

Ryberg

et al. 2011

South African Journal of Geology

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Two geophysical onshore-offshore lines on the southern margin of Africa form the Agulhas-Karoo Geophysical Transect (AKGT) and cross prominent geological features such as the Karoo Basin, Cape Fold Belt (CFB) and the Beattie Magnetic Anomaly (BMA). Geophysical data acquired along this AKGTransect between 2004 and 2007 within the Inkaba yeAfrica (lyA) framework, provide the platform for constructing a deep crustal section (IyA-200501) for the centre 100 km of the western AKGT-transect in order to resolve these features at depth. We present a detailed deep crustal model constructed from the joint interpretation of: i. archive data comprising surface geology, aeromagnetic data, nearby deep boreholes, teleseismic receiver functions and regional seismic reflection profiles, and ii. line coincident newly acquired high-resolution geophysical data consisting of near vertical seismic reflection data, shallow P-and S-wave velocity data, wide-angle refraction data, high resolution magnetotelluric data and impedance spectroscopy measurements on borehole samples. Our model differentiates four components in the up to 45 km thick crust: 1. a ~2 to 5 km thick folded Karoo Supergroup, disrupted by low-angle thrust faults rooted in a zone of local décollements in the lower Ecca Group and resting paraconformably on 2. a continuous undeformed sub-horizontal ~1.5 to 10 km thick wedge of the Cape Supergroup (CSG). This CSG wedge stretches from the Escarpment in the north to the tectonic front of the CFB in the south, and rests on an unconformity that dips about three degrees to the south. The angular unconformity is interpreted as an erosional peneplain that separates the CSG wedge from component 3. the ~13 to 21 km mid-crust basement below. The mid-crust contains a distinct north-dipping seismic fabric, here interpreted as 1.4 to 1.0 Ga Mesoproterozoic Namaqua-Natal Metamorphic Belt (NNMB) crust. A south-dipping mid-crustal detachment, interpreted as a ductile thrust zone, separates the mid-crust from component 4. a highly reflective ~10 to 24 km thick lower crust. The latter is interpreted as an older Palaeoproterozoic section of the NNMB (or even Archean cratonic basement), and bounded by a ~2 to 5 km thick, highly reflective bottom layer below that lies subparallel to a clear Moho. This bottom layer is interpreted as a mafic underplate, metasomatic reaction zone, or lower-crust to mantle transition zone. Collectively the seismic reflection and wide-angle refraction data support an interpretation that the NNMB mid-crustal layer contains the BMA source, possibly connected to two zones of strong reflectivity: a ~10 to 12 km wide northern zone and a ~5 to 7 km wide southern zone, both about 5 km thick and 7 to 8 km below surface. We interpret the BMA source to be at least in part, a Namaqua-like massive to disseminated, deformed/metamorphosed stratiform sulphide-magnetite ore body with metasomatic overprint.

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Section: Mesoproterozoic Tectonic Settingmentioning

confidence: 99%

Section: Rodinian Connectionsmentioning

confidence: 99%

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Deep Crustal Profile Across the Southern Karoo Basin and Beattie Magnetic Anomaly, South Africa: An Integrated Interpretation With Tectonic Implications

Lindeque

Wit

Ryberg

et al. 2011

South African Journal of Geology

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“…Both regions were affected by high-grade metamorphism and deformation between 1.0 to 1.1 Ga (Jacobs et al, 1993). However, there are distinct geological and isotopic differences (crustal model ages and geochronology) between the Natal and the Namaqualand, and a number of separate terranes have now been identified (Jacobs et al, 1993;Thomas et al, 1994;Eglington and Armstrong, 2003). The Namaqualand metamorphic rocks were derived from older basement (1.3 to 1.8 Ga), whereas the Natal rocks comprise of a mosaic of eastwest elongated volcanic/plutonic arc terranes dating around 1.1 to 1.4 Ga (Thomas et al, 1994;Eglington and Armstrong, 2003).…”

Section: Geological Settingmentioning

confidence: 99%

Comparison of electrical conductivity structures and 2D magnetic modelling along two profiles crossing the Beattie Magnetic Anomaly, South Africa

Weckmann

Jung

Branch

et al. 2007

South African Journal of Geology

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“…The observed coefficient of variation in the Pb/U ratios measured for the SL13 standard was 2.49% for the analytical session. The Pb/U ratios have Thomas et al, 1994).…”

Section: Introduction and Geological Settingmentioning

confidence: 99%

Geochronology of the Sikombe Granite, Transkei, Natal Metamorphic Province, South Africa

Thomas

Armstrong

Eglington

2003

South African Journal of Geology

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A new U-Pb SHRIMP zircon date of 1181 ± 15 Ma has been obtained from a sample of the syntectonic, gneissose Sikombe Granite from northeastern Transkei (Eastern Cape Province). The outcrops form the most southerly exposures of the ~1.1 Ga Natal Metamorphic Province (NMP). Previously, these isolated outcrops have been regarded as possibly forming a separate southerly, amphibolite facies terrane of the NMP, as the lithological assemblage is somewhat different from those of the granulite grade Margate terrane to the north. The new data do not conclusively demonstrate this, but they do show that the accretion age of the southerly terrane of the NMP is not significantly younger than the more northerly terranes. Sm-Nd analyses of three samples of the Sikombe Granite give consistent, positive ⑀ Nd values (+4 at t = 1180 Ma) showing that, like the rest of the NMP, the granite was derived from juvenile Mesoproterozoic crust, with little or no involvement of older material in its genesis

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The Kibaran of southern Africa: Tectonic evolution and metallogeny

Cited by 152 publications

References 45 publications

Deep Crustal Profile Across the Southern Karoo Basin and Beattie Magnetic Anomaly, South Africa: An Integrated Interpretation With Tectonic Implications

Deep Crustal Profile Across the Southern Karoo Basin and Beattie Magnetic Anomaly, South Africa: An Integrated Interpretation With Tectonic Implications

Comparison of electrical conductivity structures and 2D magnetic modelling along two profiles crossing the Beattie Magnetic Anomaly, South Africa

Geochronology of the Sikombe Granite, Transkei, Natal Metamorphic Province, South Africa

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