Summary:
The Steelpoortdrift Project is located within the Eastern Limb of the Bushveld Complex which is the world’s largest igneous intrusion and spans approximately 450km in width, 66,000km2 in area and up to 9km in thickness. Stratigraphically, the Bushveld Complex is comprised of three intrusive suites, namely the Rustenburg Layered Suite (“RLS”), Rashoop Granophyre Suite and the Lebowa Granite Suite.
The RLS is host to mafic layers rich in platinum group elements (“PGEs”), nickel, copper, chromium and vanadium. The RLS is sub-divided into four stratigraphic zones namely the Upper Zone, Main Zone, Critical Zone and Lower Zone. Only the Upper Zone is of relevance to the Steelpoortdrift Project and comprises a layered succession of ferrogabbros, troctolites, anorthosites and magnetite layers.
The Bushveld Complex is a saucer-shaped, layered igneous intrusion emplaced as multiple injections or pulses of sulphide rich magma. Crystal fractionation of the magmas into immiscible silicates and sulphides formed the layering. The sulphides scavenged the PGEs and other metals from the melt and deposited them into the sulphide layers. The layers or reefs are typically gently dipping tabular bodies, which are identifiable across hundreds of kilometres.
Vanadium predominantly reports, but not only, to the magnetite layers, with controls on mineralisation being related to oxygen fugacity and temperature of the melt. Vanadium mineralisation occurs within four vanadiumbearing titano-magnetite-rich layers which are located at the base of the Upper Zone. A distinct anorthosite layer is present near the contact with the Main Zone. Previous work focussed on the various layered zones or units present namely; the Main Magnetite Layer Mineralised Zone (“MMLZ”), the Upper Mineralised Zone (“UMZ”), the Intermediate Mineralised Zone (“IMZ”) and the Lower Mineralised Zone (“LMZ”), with average thicknesses of 5m, 19m, 14m and 12m, respectively. These units are each comprised of varying thicknesses magnetite, magnetite gabbro, gabbro and anorthosite.
Dimensions
The UMZ and LMZ have been mapped along strike (NW-SE) for approximately 4km and intersected in drilling for approximately 1.7km to the SW (distance from outcrop to furthest drilling. The thickness of the layers ranges from 5m to 37m (not true thickness).