A MULTI-STAGE ORTHOMAGMATIC AND PARTIAL MELTING HYPOTHESIS FOR THE DRIEKOP PLATINIFEROUS DUNITE PIPE, EASTERN LIMB OF THE BUSHVELD COMPLEX, SOUTH AFRICA

摘要

The occurrence of platiniferous dunite pipes is restricted to four localities in the eastern limb of the Bushveld Complex.They comprise wholly discordant bodies aligned perpendicular to the regional layering, and reveal a complex internal zonation.They remain poorly understood, despite a number of contributions dealing with the ore mineralogy, due mainly to the fact that field relationships and the silicate and oxide mineralogy have not been adequately addressed. The principal geological features of one such pipe, at Driekop, are revisited on the basis of detailed mapping and sampling of mine workings that are not generally accessible. The pipe forms a subcircular body (diameter 300 m) that is persistent to considerable depth. The principal unit is a stock-like body composed entirely of fine-to-medium grained magnesian dunite (Fo83.4).