Browsing by Author "Coetzee, Megan"

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    Geochemistry of selected South African group I, group II and transitional kimberlites located on and off the Kaapvaal craton
    (2004) Coetzee, Megan; Le Roex, Anton
    Eighteen Jurassic to Cretaceous South African kimberlites representative of group 1, group 11 and transitional varieties that have been emplaced through both the Archean Kaapvall craton (on-craton) and Proterozoic Namaqua-Natal belt (off-craton), have been selected for a comparative study aimed at characterising their geochemistry and source region compositions, as well as understanding the petrogenetic processes that have affected them. The petrography of the analysed kimberlites is similar to typical group 1 and group 11 kimberlites, characterised by deformed and anhedrarl olivine and phlogopite macrocrysts, with more subhedral to euhedral olivine and phlogopite phenocrysts and microphenocrysts, set in a groundmass of mostly serpentine, calcite and phlogopite (group 1 kimberlites), or calcite, serpentine, phlogopite and diopside (group 11 kimberlites). The transitional kimberlites tend to show intermediate characteristics, with the on-and off-craton transitional kimberlites showing more similarity to group 1 and group 11 kimberlites, respectively.