Tabular intrusion and folding of the late Archaean Murehwa granite, Zimbabwe during regional shortening

Blenkinsop, Tom G. and Treloar, Peter J. (2001) Tabular intrusion and folding of the late Archaean Murehwa granite, Zimbabwe during regional shortening. Journal of the Geological Society, 158(4), pp. 653-664. ISSN (print) 0016-7649

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Abstract

The late Archean Murehwa granite in the Zimbabwe craton is a typical member of the Chilimanzi suite of granites that occupy more than 50% of the craton. The granite has a well-defined compositional layering on a metre-scale that generally dips shallowly and has a circumferential pattern near the margins of the granite. The layering is folded on scales from metres to hundreds of metres about sub-horizontal east-west axes. Layering on a scale of tens of metres thick is parallel to the smaller scale layers. Microcline phenocrysts are generally strongly aligned parallel to the layering, but also locally cross-cut the layering in an axial planar orientation. Microstructures demonstrate that no significant deformation occurred: fabrics are thus magmatic. The Murehwa granite was intruded in a tabular sheet that may have been only a few kilometres thick, possibly fed by dykes, contrary to previous concepts of diapirism/ballooning for the late Archean granites of the Zimbabwe craton. The consistent orientation of magmatic folds and axial planar fabrics demonstrate that the granite was intruded during regional north-south shortening, consistent with the orientation of cratonic-scale extension fracturing during the intrusion of the Great Dyke, that occurred within 20 Ma prior to the intrusion of the Murehwa granite

Item Type: Article
Uncontrolled Keywords: granites, intrusions, magmatic fabric, folding, crustal shortening, u-pb zircon, south-mountain Batholith, experimental deformation, great dyke, Chindamora batholith, tectonic evolution, limpopo-belt, Nova-Scotia, emplacement, craton
Research Area: Earth systems and environmental sciences
Faculty, School or Research Centre: Faculty of Science (until 2011) > School of Geography, Geology and Environment > Centre for Earth and Environmental Science Research (CEESR)
Depositing User: Peter Treloar
Date Deposited: 16 Oct 2007
Last Modified: 28 Feb 2012 11:59
URI: http://eprints.kingston.ac.uk/id/eprint/1770

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