The Kaapvaal craton covers an area of approximately 1.2 million square kilometers and is welded to the Zimbabwean craton to the north by the Limpopo Belt, a late Archean orogenic belt (Fig. 1). To the south and west, the Kaapvaal craton is flanked by Proterozoic orogens, and to the east by the Lebombo monocline that contains Jurassic igneous rocks associated with the breakup of Gondwana. The Kaapvaal craton formed and stabilized between 3.7 and 2.6 billion years ago and is a mixture of early Archean (3.0-3.5 Ga) granite greenstone terranes and older tonalitic gneisses (ca. 3.6-3.7 Ga), intruded by a variety of granitic plutons (3.3-3.0 Ga), in turn overlain by a succession of late Archean basins (3.0-2.5 Ga) filled with thick sequences of both volcanic and sedimentary rocks. The early Archean crust is well exposed only on the east side of the craton and comprises a collage of subdomains or crustal blocks characterized by distinctive igneous rocks, deformation history, and tectonic style (Fig. 1).