3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item An integrated geochemical and isotopic study of the Prieska Province kimberlites from the Republic of South Africa(1994) Clark, Trevor, CharlesRb-Sr emplacement ages of nineteen kimberlites from the Prieska Province vary from 74 to 174 Ma, Their isotopic, whole-rock geochemical signatures and perovskite REE distributions were also determined. Non-micaceous and micaceous kimberlites from the area show similar petrographic, geochemical and isotopic compositions relative to cratonic kimberlites, indicating similar sub-continental mantle source compositions in the two tectonic environments. Transitional varieties of kimberlite, which can be defined petrographically, geochemically and isotopically are also recognised from the area, but are not prevalent in the cratonic environment. The Prieska Province kimberlites are possibly derived by partial melting processes within a subcontinental reservoir characterised by a spectrum of compositions from time-averaged depleted (HllMU) to enriched (Group II). The occurrence of these components in both on- and off-craton settings indicates that the kimberlite source area is not strictly linked to the suberatonic lithosphere. Mantle' plume sources are not favoured because of the variable source compositions and distribution of emplacement ages within the Province. Transitional kimberlites were derived from a source component with mixed character, not yet noted from within the Kaapvaal Craton. This is the first documented example of isotopically transitional kimberlites from southern Africa.