Regional geological setting of the Limpopo Belt

Abstract

The ∼ 2.7 Ga Limpopo Belt granulite terrane is situated between two lower-grade granite-greenstone cratons, the Kaapvaal Craton in the south and the Zimbabwe Craton in the north. This granulite-facies terrane is subdivided into three zones, each with a distinctive geological signature and separated from each other, and from the adjacent cratons, by well defined shear zones: (1) the Southern Marginal Zone, composed of granite-greenstone material very similar to that of the Kaapvaal Craton, has retrogressed granulites on its southern margin in the hanging wall of the northward-dipping terrane boundary (Hout River Shear Zone) separating the granulite terrane from the adjacent Kaapvaal Craton; (2) the Northern Marginal Zone, a granite-greenstone terrane at granulite grade, which is separated from the Zimbabwe Craton by a southward-dipping terrane boundary; and (3) the Central Zone, a unique crustal element, with distinctive carbonate platform lithologies and a metagabbroic layered complex which intruded before or at ∼ 3250 Ma. This zone cannot be related to the Kaapvaal Craton or to the Zimbabwe Craton. It is separated from the two Marginal Zones by mylonitic shear zones with horizontal stretching lineations. The entire Limpopo Belt is characterized by a distinctive deformational and metamorphic style which contrasts markedly from that of the adjacent granite-greenstone terranes of the Kaapvaal and Zimbabwe Cratons. This distinctive pattern developed during the Limpopo Orogeny, probably as a consequence of continental collision during the late Archaean.