HIMALAYAN-TIBETAN ANALOGIES FOR THE EVOLUTION OF THE ZIMBABWE CRATON AND LIMPOPO BELT

The Limpopo Orogeny, which lasted from approximately 2700 to approximately 2600 Ma, was characterised by NNW-SSE directed shortening. This resulted in both crustal thickening, accommodated by folding and NNW-directed thrusting, and associated crustal extrusion whereby a number of crustal blocks, including the Central Zone of the Limpopo Belt, was displaced to the west-southwest along WSW-ENE trending shear zones. This was part of a regionally distributed phase of orogenic deformation which affected the adjoining Kaapvaal and Zimbabwe Cratons from the Witwatersrand Basin in the south to the Harare Greenstone Belt in the north. This deformation, which migrated northwards with time, postdated an earlier phase of crustal accretion during which the Archaean crustal unit now marked by the Kaapvaal and Zimbabwe Cratons and the Limpopo Belt, grew towards the north-northwest. Shortening of this unit during the Limpopo Orogeny may be regarded as the last stage of the crustal accretion process. This tectonic process of continental growth by accretion followed by crustal shortening with associated crustal extrusion has many features in common with Tibetan tectonics from the Mesozoic to the present.