Bushveld event

The evidence reported by Nguuri et al. (2001) for a thick crust and a relatively diffuse Moho in the Bushveld Province supports the argument for a broadly continuous mafic body at depth beneath the Bushveld Complex (Cawthom et al. 1998 Webb et al. 2000 Cawthom Webb 2001). The substantial load of material added to the cmst during the Bushveld event was interpreted by Webb and coworkers to have produced a downward crustal flexure of up to 6 km with a resultant crustal thickness of 45-50 km beneath stations located in the central Bushveld Province (Webb et al. 2000). 

Despite the abundant evidence for huge plume events, such as the immense Bushveld event, the anthropic principle implies that the whole Earth has not experienced 2>100°C greenhouse conditions as long as life has existed. Since then, there have always been parts of the Earth below about 100°C, and since the evolution of mesophiles there have been parts of the Earth below about 40°C. Possibly the plume events have simply been too small to disrupt global climate beyond habitability. Or possibly life itself has played a hand. 

To date, Re-Os isotope studies of peridotite xenolith suites, taken to be representative of the lithospheric mantle beneath continents, reveal that although some lithospheric mantle began to form beneath continents in Palaeo- to Mesoarch-aean time, major crustal differentiation events continued until Neoarchaean time when, at least in southern Africa, significant volumes of lithospheric mantle formed and stabilized the newly accreted continent. On the Kaapvaal Craton, major magmatic events such as that which formed the Bushveld intrusion, substantially modified or introduced new material into the lithospheric mantle (Carlson et al. 1999) and the lower crust (Schmitz Bowring 2000), but the craton retained its integrity for another 2 Ga. 

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