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

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