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

[Tim Donovan <uwrk2@yahoo.com>]

--- David Marjanovic <david.marjanovic@gmx.at> wrote:

> >> The magnetostratigraphy mentioned in the above
> >> abstract suggests that the Barun Goyot, Djadoktha
> >> and Nemegt Formations are all upper Campanian-
> >> Lower Maastrictian in age,
> >
> >  This makes no sense; they couldn't be
> contemporaneous.
> 
> Nobody said they were. 


 Yes they did, see above, supposedly they are ALL
upper Campanian-lower Maastrichian in age. Supposedly
they all spanned the same chrons.

>Maybe the Djadokhta is upper
> Campanian, the 
> Baruungoyot is around the CMP-MAA boundary, and the
> Nemegt is lower 
> Maastrichtian?
> 
> > 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.
> 
> Looks like you agree. :-)
> 
> > The Djadokhta is only coeval with the lowest part
> of
> > the Horseshoe Canyon, and the Nemegt only the
> upper
> > part.
> 
> Where did you get that precision? 

 See above-radiometric dating for the Djadokhta- and
in part, the presence of Saurolophus in the upper
Horseshoe Canyon and Nemegt. Btw Norman considered S.
angustirostris "virtually indistinguisable" from
S.osborni.
> 
> 



                
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