Blythefan. Actually I agree with most of what you say. Yes most...

Blythefan. Actually I agree with most of what you say. Yes most of the uraninite is commonly micro particles in pyrobitumin (carbon/ thucolite call it what you like) - exactly what I said- I used the word 'rafts'. This is the end stage of carbon infiltration. The uraninite starts off as rounded grains before carbon infiltration and before it gets fractured. There are, however, many unfractured or fractured rounded grains of uraninite not associated with carbon. If not detrital maybe colloidal? Carbon infiltrates and assimilates the uraninite and clearly posts dates it. Less obvious in the CLR but seen in the other oligomictic reefs with 'flyspeck' carbon where carbon deposits on the uraninite. No algal mats there. All this takes place in shears, fractures and splays. The uraninite originally may not be detrital but its hard to explain the degree of rounding prior to fracturing or interaction with the carbon. Maybe a replacement?

Source of hydrocarbons could be West Rand Group shales although these are not particularly organic rich. They are black due to the magnetite contents, not the carbon. The source of the carbon would be of peripheral interest.

Gold deposition is principally on the outside of the carbon grains which would indicate carbon first. Maybe unmixing of thiosulphide complexes: H2S partitions into the organic phase and gold drops out.

That said the degree of brittle deformation we see in the reefs did not take place in a pond with unconsolidated sediments. Shears, splays and fractures are the clue.