A wide range of geochemical studies directed at understanding the mechanisms of origin of the craton and its geologic evolution are being undertaken as part of the Kaapvaal Project. These include:
Chemical and isotopic characterization of lithospheric mantle beneath the Kaapvaal craton. This characterization is possible through petrofabric, petrologic, isotopic and chemical studies of mantle xenoliths brought to the surface by numerous kimberlite pipes that have perforated the craton over a period of >2.0 Ga. These studies will provide essential data for interpretation of the seismic imaging as well as direct input into models of craton assembly, stabilization and reactivation.
Geochemical, geochronological, field and experimental petrology studies of komatiites and lithospheric peridotites to develop models for the depth range and physical conditions (temperature range and volatile contents) of melt extraction and mantle depletion. The results of these studies will be integrated with petrologic studies of xenoliths to test for a genetic relation between depleted lithosphere and magma generation.
Geochronologic, geochemical and petrologic studies of the lower crustal rocks of the Kaapvaal craton to establish the time-temperature history of crust formation and its relation to mantle lithosphere stabilization beneath the Kaapvaal craton.
Re-Os isotopic study of picrites from the Karoo flood basalt province to examine the degree of involvement of the Kaapvaal lithospheric mantle in the genesis of these Jurassic flood basalts associated with the break-up of Gondwana.
Figure 1. Plot of Mg/(Mg+Fe) in mole percent (Mg-number) against modal olivine in weight percent for low-temperature peridotites from both the Kaapvaal and Siberian cratons. The arrows identified as Oceanic Trend describe the compositional change from fertile peridotite (lower end) to depleted residues (upper end) including abyssal peridotites, alpine peridotites and ophiolite tectonites.