1887

oa South African Journal of Geology - SHRIMP U-Pb zircon geochronology of granites from the Central Zone, Limpopo Belt, southern Africa : implications for the age of the Limpopo Orogeny

Volume 101 Number 4
  • ISSN : 1012-0750
  • E-ISSN: 1996-8590

 

Abstract

This paper presents new U-Pb (SHRIMP) data for zircons from syn- and post-tectonic granites in the western part of the Central Zone, Limpopo Belt, southern Africa. These data are used to assess constraints on the timing of collisional orogeny in the Central Zone. The Selebi-Pikwe and Makowe Hills granites are Late Archaean in age. Field and fabric relationships indicate that these syntectonic granites intruded during the Limpopo Orogeny, thereby providing a minimum age constraint on the contractional stage of orogenesis. This interpretation suggests that recently published mineral ages of c. 2.0 Ga from the eastern part of the Central Zone date metamorphism during reworking of Archaean age shear zones, rather than collision between the Kaapvaal and Zimbabwe Cratons. The Mahalapye granite in the extreme western part of the Central Zone is a post-tectonic intrusion that crystallized at 2023 ± 7 Ma. The granite is unconformably overlain by rocks of the Palapye Group for which it provides a maximum age.

Hierdie artikel bied nuwe U-Pb (SHRIMP) data aangaande sirkone uit sin- en na-tektoniese graniet in die westelike deel van die Sentrale Sone, Limpopogordel, suidelike Afrika. Hierdie gegewens word gebruik om tydsafgrensing vir die botsingsorogenie in die Sentral Sone te bepaal. Die Selebi-Pikwe en die Makowe Hills-graniete dateer uit die laat Argeïkum. Veld en maakselverhoudings dui aan dat hierdie sintektoniese graniete tydens die Limpopo-orogenie binnegedring het wat as 'n minimum ouderdom vir die krimping-stadium van die orogenese kan dien. Hierdie interpretasie doen aan die hand dat die onlangs gepubliseerde mineraalouderdomme van ongeveer 2.0 Ga, afkomstig uit die oostelike dee! van die Sentrale Sone, metamorfisme tydens herwerking van skuifskeursones met 'n Argeïese ouderdom dateer, eerder as die botsing tussen die Kaapvaal- en Zimbabwekratons dateer. Die Mahalapye-graniet, in die verre westelike dee! van die Sentrale Sone, is 'n posttektoniese intrusie wat teen 2023 ± 7 Ma gekristalliseer het. Die graniet word diskordant oorle deur gesteentes van die Palapye Groep waarvoor die graniet 'n maksimum ouderdom verskaf.

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/content/journal/10520/EJC-1ac8f6f0de
1998-12-01
2020-09-26

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