Falk,
I'm glad to hear it's someone else's idea. Archean land life!
Sounds crazy.
I would expect gold to recrystallize during even 250-300°C
metamorphism. I know that Neil Phillips has argued that the Wits gold
was remobilized in part.
Gold grows in placer deposits? That also seems unlikely. I
could imagine it accreting but how much of it would ever touch another
grain?
eric
On Jun 23, 2008, at 4:59 PM, Falk H. Koenemann wrote:
> "Eric Essene" <[log in to unmask]> schrieb:
>> Falk,
>> This seems like a farfetched interpretation to me somehow. Why
>> do you conclude you have lichens? That would imply formation on
>> land. Why can't the gold result from local reduction rather than
>> being physically trapped?
>> cheers,
>> eric
>
>
> Hi Eric,
>
> the lichen interpretation is not mine, but that of one of the
> researchers on that subject at the time, Hallbauer, who was my boss at
> the Chamber of Mines of South Africa then. He has published a number
> of articles on this.
>
> Indeed the lichen layers are interpreted to have formed subaerially.
> Regarding the gold, you see the detrital gold particles in the
> conglomerate in Xray stereographs, but the extremely fine gold beneath
> the Thucholite had been transformed chemically, probably in the same
> way as gold nuggets grow in a placer deposit from thin gold
> concentrations.
>
> Falk
>
>
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