Late Archaean to early Proterozoic granitoid magmatism and high-grade metamorphism in the central Limpopo Belt, South Africa

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doi: 10.1144/gsjgs.154.1.0025
Authors:Jaeckel, P.; Kröner, A.; Kamo, S. L.; Brandl, G.; Wendt, J. I.
Author Affiliations:Primary:
Universität Mainz, Institut für Geowissenschaften, Mainz, Federal Republic of Germany
Max-Planck-Institut für Chemie, Federal Republic of Germany
Royal Ontario Museum, Canada
Council for Geoscience, South Africa
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, Vol.154 (Part 1), p.25-44. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:1997
Note:In English. 88 refs.; illus., incl. 5 tables, sketch maps
Summary:New single zircon U/Pb and Pb/Pb ages are reported for granitic gneisses, supracrustal rocks and anatectically derived granitic melt patches in the area around Messina, South Africa. The Sand River gneiss is a composite suite of tonalitic to trondhjemitic rocks with protolith ages of 3200-2600 m.y. and the Singelele gneiss, a heterogeneous granodioritic to quartz monzonite rock, has protolith ages of 2580-2550 m.y.; since both gneisses experienced polyphase high-strain ductile deformation, this must have occurred later than 2550 m.y. ago. Granulite-facies pelitic gneisses of the Beit Bridge complex contain abundant spherical multifacetted zircons which reflect new zircon growth near the peak of metamorphism; these zircons give a mean age of 2026.5 ± 6.3 m.y., interpreted as reflecting a high P-T event (>><[dollar]I> 10 kbar, 825 ± 25°C). Granitic melt patches in the metapelites as well as in the Sand River gneiss and anatectic granites are probably related to rapid near-isothermal decompression to <<<[dollar]I> 3-5 kbar and 600-750°C; these rocks contain new magmatic zircons dated at 2005.6 ± 4.4 m.y., probably reflecting a crustal melting event resulting from rehydration of the granulitic assemblage. These results support the suggestion of a single granulite-facies event, probably at ∼ 2027 m.y. ago. The 'Limpopo orogeny' is not an Archaean event but took place in the early Proterozoic. [R.A.H.]
Subjects:Absolute age; Archean; Dates; Facies; Gneisses; Granulite facies; High-grade metamorphism; Magmas; Metamorphic rocks; Metamorphism; Neoarchean; Nesosilicates; Orogeny; Orthosilicates; P-T conditions; Paleoproterozoic; Pb/Pb; Precambrian; Proterozoic; Silicates; U/Pb; Upper Precambrian; Zircon; Zircon group; Africa; Limpopo Belt; South Africa; Southern Africa; Beit Bridge Complex; Igneous activity; Sand River Gneiss; Singelele Gneiss
Abstract Numbers:97M/3079
Record ID:1997056622
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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