CHARACTERIZATION OF THE KOLO KIMBERLITE PIPE: CONSTRAINTS on THE COMPOSITION AND GENESIS OF THE DIAMONDIFEROUS LITHOSPHERIC MANTLE BELOW THE EASTERN MARGIN OF THE KAAPVAAL CRATON

The Kolo kimberlite pipe presents a unique opportunity to study a diamondiferous kimberlite deposit in southern Africa, close to the margin of the Kaapvaal Craton before extensive mining has occurred. The Kolo pipe forms part of a group of five Type-II kimberlite pipes and eight associated dykes in the lowlands of Lesotho.

Three main kimberlite lithofacies have been identified within the pipe. The undifferentiated kimberlite (UVK) lithofacies is relatively hard, bluish-green in colour, contains few xenoliths and spatially restricted to the central-western portion of the pipe. Xenolith-rich kimberlite (XVK) lithofacies is tuffaceous, xenolith-rich, weathers to a soft friable yellowish-green, yellow or pale brown material and is restricted to the northwestern and eastern portions of the pipe. Kimberlite breccia (KBX) lithofacies is characterised by a friable, yellow or greenish-brown kimberlite and contains numerous sheared or tectonically rounded clasts. KBX kimberlite is spatially restricted to a cross-cutting fault that separates lithofacies UVK and XVK in the northwestern portion of the Kolo pipe. Previous study indicates that UVK kimberlite contains better grades than the softer XVK lithofacies. This is potentially due to dilution of the kimberlite by country rock xenoliths.

This study seeks to map, petrologically and geochemically characterise kimberlite, xenoliths and xenocrysts of the Kolo kimberlite. The study of which is designed to elucidate the current understanding of the diamondiferous lithospheric mantle close to craton margins, assisting in our understanding and exploration for similar types of kimberlite deposits. The results of which will be used in comparative studies with associated kimberlites in the Sekameng-Kolo Kimberlite Group and other craton margin limberlites (i.e. Letšeng).