The "DIRT" went 11.8 grams per tonne, page-64

Esh the theories are being developed on the run here, at this stage there is not enough information about the deposit, nor is there any comprehensive well constructed theory that explains the gold embedded in those conglomerates at Purdy's and I think the attempt to somehow link it to the Witwatersrand geology might turn out to be a bit of a cul de sac, possibly created by Quentin H because that was a theory he was working on previously and does not want to walk away from it, and hell it might turn out to be right in the end. But the theories of Archean formation and then later transport and deposition, and a reasonable local model based on current observation are two different things, and for the moment a model would be very useful, but more field work needed - and by the way i read that report that your first quote comes from as proposing emplacement by glacial action in a high energy marine environment but possibly many aeons after the algal scavenging that might have concentrated the originally chemically mobilised gold. If nothing else this has got the rock doctors talking and I expect a lot of historical exploration reports across this area are being dusted off now for review.