Bushveld intrusion

As discussed previously, numerous Premier peri-dotites give ages close to 2.0 Ga (Pearson et al. 1995a Carlson et al. 1999). The Premier kimberlite erupted near the 2.05 Ga Bushveld intrusion and the Palaeoproterozoic model ages probably reflect substantial modification of the lithosphere beneath this region at c. 2Ga plus possibly some new lithospheric material (Carlson et al. 1999). 

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. 

Layered intrusions. Chlorine isotope studies of the Stillwater Complex of Montana, USA (e.g., Stewart et al. 1996 Boudreau et al. 1997), and the Bushveld Complex in the Republic of South Africa (e.g., Willmore et al. 2002) show that both intrusions are anomalously rich in chlorine (e.g., Boudreau et al. 1986 Willmore et al. 2000), but that, their chlorine-isotopic compositions are distinct from one another (Fig. 1). The 8 Cl values of Stillwater samples range from -0.93%o to 0.27%o with all but one value below 0.1 %o (Fig. 1). In contrast the... 

Most of the world s chromium reserves occur in large, layered mafic/ultramafic intrusions such as the 2.06 Gyr old Bushveld Complex in the Republic of South Africa, where nearly mono-mineralic layers of chromite appear to result from the mixing of primitive and evolved liquids that... 

Ford AB (1970) Development of the layered series tmd capping granophyre of the Dufek intrusion of Antarctica. In sser DJL, von Gruenewaldt G (eds) Symposium on the Bushveld igneous complex and other layered intrusion. Geol Soc South Africa, Spec Pub 1 492-510... 

The mineralization age is close to that of widespread igneous activity in South Africa, such as intrusion of the Bushveld Complex and metamorphism of the Witwatersrand system, at 1,950 m.y. (Nicolaysen et ai, 1958). The lead isotopic data support the petrologic evidence presented by Liebenberg (1955) that the lead was largely derived from detrital uraninite in the Dominion Reef conglomerate. 

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