Re-healing cratonic mantle lithosphere after the world's largest igneous intrusion: Constraints from peridotites erupted by the Premier kimberlite, South Africa

Constraining the processes that drive the disruption and re-healing of cratonic mantle roots is essential in understanding how cratons evolve. A striking example of this “cycle” of disruption and re-healing is provided by the deep mantle root currently observed beneath the ∼2.05 Ga Bushveld-Molopo Farms Complex (BMFC) of the central Kaapvaal Craton. Magmatism that produced the BMFC involved considerable disruption of the craton mantle root, yet the diamondiferous nature of the root, as sampled by Mesoproterozoic kimberlite eruptions, indicates that following Paleoproterozoic disruption, the lithosphere was re-healed and a cool geotherm re-established. A snap-shot of this mantle root provided by 48 peridotite xenoliths from the ∼1.2 Ga Premier (now Cullinan) kimberlite allows us to examine the evolution of the central Kaapvaal mantle lithosphere to constrain this re-healing process. Premier peridotites can be classified into 3 petrographic groups: an olivine-rich group (>80% olivine), with predominantly Archean Re-depletion (TRD) ages (Group I), a more orthopyroxene-rich group (Group II;