Tectonic controls on kimberlite location, southern Africa

The relationship between kimberlite (the host to diamonds) ascent paths from mantle depths >150 km to surface and major structures is controversial. We use a geometric method of spatial analysis (SpaDiS™), which requires neither statistics nor algebraic models to show that crustal architecture is critical in the localisation of kimberlites. Distinct corridors of kimberlites are parallel to, but not within, prominent shear zones and crustal faults. Instead the kimberlites occur in relatively homogeneous, strong crust capable of maintaining the very high CO2 pressures necessary for rapid emplacement. Archaean directional trends in kimberlite distribution are recognised on craton, whereas Proterozoic and Carboniferous–Permian (Karoo) age trends are recognised both on and off the Archaean craton.