Petrogenesis of the Northwest Corner intrusive phases, Dutoitspan kimberlite, South Africa

The Outoitspan Group 1 kimberlite pipe forms part of the well-known cluster of pipes located in and around the city of Kimberley, South Africa. Eight macroscopically distinct intrusive phases, i.e. D2 Type 2, D2 Type 3, D2/D5, D5, D18, Type 5, D16 and the D16 dyke are present in the Northwest Corner area of the mine. Microscopically they range from macrocrystic to aphanitic hypabyssal (magmatic) kimberlites with varying amounts of opaque minerals, monticellite and phlogopite. Olivine is the dominant macrocryst phase and alteration varies from unaltered to highly serpentinised. These intrusive phases also contain variable amounts of crustal xenoliths.