One must remember that the real Wits is very aerially extensive...

One must remember that the real Wits is very aerially extensive but only crops out in a few places such as the Vredefort Dome, Johannesburg (original discovery by an Australian, George Harrison) and Klerksdorp area. The lower Wits (West Rand Group) has little gold except near Klerksdorp. The upper Central Rand Group is extensive but less so. Most of the basin is covered by younger volcanics, Proterozoic and Phanerozoic intracratonic sediments. Obviously exploration below cover, especially deep cover, has its own challenges and costs. There is little unconsolidated cover as the basin lies below an extensive erosional regime, the Great African Divide in places.

The secret to finding a Wits analogue is finding what enriched the Wits in gold so much compared with the likes of Elliott, Athabasca, Jacobina etc which are similar basins with similar conglomerates. If one studies the Wits one discovers that the gold in the oligomictic reefs (the majority) is present in shears, fractures and splays. There is a lot of evidence of cataclasis or shock metamorphism such a psuedo mylonitic textures, grain crushing, pressure fringes (generally unrotated), undulose quartz, neobastic growth, dilation and shearing.

Gold is mostly resident in these fractures. The reefs are very high energy environments, probably prograding fan deltas. Gold is obviously secondary (resident in the fractures and is very fine grained) and ditto the carbon. Pyrite is obviously a replacement product as cm size pyrite grains cannot have survived in that high energy environment. Quartz cobbles show extensive pressure solution where Fe oxide grains blew up like balloons on sulphidation. The molar volume of pyrite is much greater for the equivalent iron. The fractures develop in the reefs due to lithological competency contrasts (in layman's terms what doesn't bend, breaks).

The question we should be asking is if we see the same structures in the Pilbara rocks?

(Been there, done that, got the T shirt).