Multiphase Emplacement of the PGE-bearing Platreef in the Northern Limb of the Bushveld Complex

The Platreef in the northern limb of the Bushveld Complex is a major world resource of PGE with significant Ni and Cu credits. It is dominantly a pyroxenitic package that comprises a composite set of sills, each with a distinctive geochemistry, PGE and base metal abundance. The Platreef package may exceed 400m in thickness, but this is due in part to thick metasedimentary interlayers that may occur between the sills. Some of these interlayers may be in situ relics rather than xenoliths. Recent data derived from whole rock geochemistry including Mg#, and Cr content and microprobe analyses of chromitite compositions, suggests that the uppermost Platreef 'sill' with simple Pt-dominated mineralogy and highest PGE tenors sometimes associated with chromitite layers and stringers, can be correlated with the Merensky Reef. Other Platreef sills have geochemical parameters that are similar to those of the upper Critical Zones of the eastern and western limbs.