Abstract:
Carbonatites are exotic rocks which usually occur in discrete intrusions. Considering the
association of carbonatites with rifting environments, this dissertation proposes that:
carbonatites occur in extensional tectonic settings and therefore carbonatite occurrence can be
used to constrain an extensional setting for related occurrences. In order to give context in
which to consider this hypothesis, the formation of carbonatites is reviewed. This work favours
the direct mantle melting model as it is most relevant and consistent with observations of
Kaapvaal Craton carbonatites. However the liquid immiscibility model cannot be entirely
rejected with current knowledge. The hypothesis is applied to the Bushveld Igneous Complex
after providing evidence of the rift-carbonatite association. The Bushveld Igneous Complex is
considered to have been emplaced in the same tectonic setting as carbonatites. Therefore the
Bushveld Igneous Complex was emplaced in an extensional tectonic setting. Finally the
carbonatites which are part of the Pilanesberg Alkaline Province are considered in order to test
the hypothesis. This work finds that the Pilanesberg carbonatites do occur with other rift related
magmatism during the break-up of Nuna (Columbia) and therefore the hypothesis is not
rejected. This work offers reviews of basic carbonatite background, formation models and
carbonatite occurrences on the Kaapvaal Craton.
