RE:RE:High GradingMy comment about potential high grade conglomerates follows the location of high grade Egina gold nuggets in valleys. However, I accept that this principle may be more difficult to apply to the laying of Beatons Creek conglomerate gold, since the conglomerate gold content will be dwarfed by the weight of the host rock. Nevertheless, any free gold in the conglomerate layers is likely to be concentrated in valleys, as with Egina free gold nuggets.
https://www.csiro.au/en/Research/MRF/Areas/Resourceful-magazine/Issue-16/Pilbara-goes-for-gold Extract below:-
Formation of Pilbara conglomerate gold still a mystery
CSIRO’s Dr Pearce says the search for an answer to the forces that created the Pilbara conglomerates, which lie between the very old Archaean basement and the later Fortescue group of rock units, have narrowed to focus on what must have been a very wet and high energy environment.
But, even that general hypothesis can not explain the presence of chlorite, a soft mineral, in a halo-like pattern around some of the nuggets.
“The presence of chlorite is a puzzle that is yet to be explained,” Dr Pearce says.
Mark Creasy, one of Australia’s most successful prospectors and an early participant in the Pilbara gold hunt, agrees with the theory that the gold was deposited in a marine environment.
“It’s got to be alluvial with some kind of input with gold precipitated from water,” Mr Creasy says.
“But exactly how it was formed and whether there is a connection to events in South Africa is harder to say.
“We’re talking about a period of time covering between 2.8 and 3 billion years ago, and a lot can happen in 200 million years.”