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Re: Asteroid Impact Ended The Triassic
Title: Re: Asteroid Impact Ended The
> Still to be found is what would be a
vast crater, said Olsen, [...]
What about that Nature paper from 1997 about a possible Tr-J boundary
chain throughout North America and Europe
Spray, J. G., S. P. Kelley and D.
B. Rowley. 1998. Evidence for a late Triassic multiple impact event on
Earth. Nature 392:171-173.
Unfortunately the ranges and error bars on their dates for the
craters in this 'chain' span millions of years. So there is no
evidence, at the present resolution of dating, that these craters are
'contemporaneous' with each other, let alone the TJ boundary. Oh, and
if memory serves, they used Harland et al's 1990 date of 208 Ma for
the TJ boundary, whereas it's presently put at 202 Ma.
Likewise Manicouagan (Hodych and Dunning 1992) is supposedly 213
Ma but again the error bars (largely due to difficulties with argon
loss) span TENS of millions of years (not to mention those authors had
to discard a good third of their results to GET '213'!). But,
Manicouagan is being redated as we speak....
Hodych, J. P. and G. R. Dunning.
1992. Did the Manicouagan impact trigger end-of-Triassic mass
extinction? Geology 20:51-54.