Archean rapakivi granite-anorthosite-rhyolite complex in the Witwatersrand basin hinterland, southern Africa

The Gaborone granite suite and the Kanye Formation formed during a single magmatic event in the late Archean evolution of the Kaapvaal craton, southern Africa, and may be the oldest rapakivi granite-anorthosite-rhyolite suite in the world. The Gaborone granite suite underlies an area of >6000 km² in the northwestern part of the craton and comprises A-type rapakivi granite, leucogranite, granophyric microgranite, and minor anorthosite. It is partly surrounded by the Kanye Formation, a 1000-m-thick pile of pyroclastic and flow-banded rhyolitic lava. Precise U-Pb dating of granitic and granophyric components of the Gaborone suite and rhyolite of the Kanye Formation shows that all three rock types are the same age within error (2783-2785 Ma). Emplaced in the source area during upper Witwatersrand Supergroup sedimentation, the Gaborone-Kanye event has important implications for the tectonic and magmatic evolution of the northern Kaapvaal craton and possibly also played an important role in the development of the adjacent auriferous sediments.