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Re: Age of the Barun Goyot, Djadoktha and Nemegt Formations




--- "Jaime A. Headden" <qilongia@yahoo.com> wrote:

> Tim Donovan (uwrk2@yahoo.com) wrote:
> 
> <This makes no sense; they couldn't be
> contemporaneous. The Nemegt overlies the
> Barun Goyot which overlies the Djadokhta.
> Radiometric dating indicates the
> latter is c 75 Ma or a little younger. The Barun
> Goyot is probably latest
> Campanian-basal Maastrichtian in age and the Nemegt
> late early-mid
> Maastrichtian.>
> 
>   So the distinct geologies must span several
> million years and not be rapid
> and short-interval formations for ... what reason
> again?
> 

  Faunal turnover e.g. Pinacosaurus-Saichania-Tarchia.
The presence of Saurolophus and a tyrannosaur closest
to Tyrannosaurus in the Nemegt argues for a younger
age than that of the Djadokhta. The latter is late
Campanian but Russell and Jerzykiewicz considered the
Nemegt mid Maastrichtian. 



                
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