Petrogenesis of the Bushveld Complex and its PGE-Cr-V deposits
CET Annual Report (abstract)
Large layered intrusions are emplaced in stable cratonic or intracratonic settings, under locally extensional, but far-field compressive regimes that allow the formation of thick composite sills. The parental magmas to many of the PGE-bearing intrusions are siliceous magnesian basalts (Bushveld, Great Dyke, Stillwater, Penikat) derived from both asthenospheric and lithospheric mantle sources, and variably modified by contamination with crust during magma ascent. The existence of mineralised intrusions of tholeiitic lineage (e.g., Skaergaard) highlights that specific mantle sources or contamination are non-essential for PGE reef formation.