Carbon and U-Pb evidence for a Palaeoproterozoic crustal component in the Central Zone of the Limpopo Belt, South Africa

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doi: 10.1144/0016-764902-059
Authors:Buick, I. S.; Williams, I. S.; Gibson, R. L.; Cartwright, I.; Miller, J. A.
Author Affiliations:Primary:
La Trobe University, Department of Earth Sciences, Bundoora, Victoria, Australia
Australian National University, Australia
University of the Witwatersrand, South Africa
Monash University, Australia
University of Cape Town, South Africa
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, 160(4), p.601-612. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:2003
Note:In English. 49 refs.; illus., incl. 4 tables, geol. sketch maps
Summary:Supposedly mid-Archaean (c. 3.3 Ga) granulite-grade marbles from the Gumbu Group, Central Zone, Limpopo Belt (South Africa) have anomalously high δ13C values (+4.6 to +7 ppm) interpreted as minimum values for their limestone protoliths. Such elevated δ13C values are unknown in any Archaean carbonate worldwide, but occur in Palaeoproterozoic (c. 2.4-2.1 Ga) carbonates; for example, on the adjacent Zimbabwe and Kaapvaal cratons. This suggests that the Central Zone contains a previously unrecognized Palaeoproterozoic cover sequence, contrary to the prevailing view. This conclusion is supported by zircon U-Pb sensitive high-resolution ion microprobe ages from two metasediments, which, in addition to c. 2.02 Ga metamorphic zircon overgrowths, contain detrital zircons no older than c. 2.68 Ga, and some possibly as young as c. 2.2 Ga. The recognition of post-3.3 Ga metasediments in the Central Zone requires a major revision of models of the tectonic evolution of the Limpopo Belt.
Sections:Age determination
Subjects:Absolute age; Archean; C-13/C-12; Calc-silicate composition; Carbon; Crust; Dates; Geochemistry; Ion probe data; Isotope ratios; Isotopes; Marbles; Mass spectra; Metamorphic rocks; Metasedimentary rocks; Nesosilicates; Orthosilicates; P-T conditions; P-T-t paths; Paleoproterozoic; Precambrian; Proterozoic; Sedimentary cover; SHRIMP data; Silicates; Spectra; Stable isotopes; U/Pb; Upper Precambrian; Zircon; Zircon group; Africa; Limpopo Belt; Central Zone
Coordinates:S230000 S220000 E0300000 E0280000
Abstract Numbers:03M/3468
Record ID:2003054774
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
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