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Re: Re: "No Bolides!"
Quoting my inflammatory remarks, Tom Holtz stated (04/04/96; 1:47p):
(my words first):
>>I believe that the claim that core data from Chicxulub simply shows
>>volcanism is no longer being promoted by those (e.g. Charles
>>Officer) who once did so. The claim by marine micropaleontologists
>>(e.g. Gerta Keller) that the presumed impact did not quite
>>correspond to plankton extinctions also seems to have been
> Not to be nitpicky, but I have not seen retractions by either of
> these workers, nor have I seen any published or presentation
> refutations of Officer's data (at least).
I have seen a refutation in print of some of what Officer has published,
and I will forward the reference when I locate it. I doubt that he has
retracted anything. Keller has not, to my knowledge, retracted anything,
either. However, my observation of them, in person at the last two
national GSA meetings, is that they are no longer promoting their earlier
positions. I think they are being much more cautious now, waiting and
watching. This is in very sharp contrast to a few years ago, when they
were being VERY uncomplimentary--sarcastic even--to the bolide impact
group, with Walter Alvarez sitting right there.
>Secondly, and much more intriguing to this soft rock worker, is the
>claim that the disturbed layers are *overlain* by carbonates
>containing late Campanian and Maastrichtian microfossils. If true,
>this would require the impact/volcano/whatever to have occurred 12
>million years or more before the K/T boundary.
I seem to recall a discussion of this (at an oral session), with the
claim made that the Campanian and Maastrichtian microfossils apparently
overlying the crater are also in disturbed rock. In other words, they
apparently fell or were washed into the crater. I'm a little fuzzy on
that, but I know that an effective case for Campanian and anything but
latest Maastrichtian age has not been presented for Chicxulub at any
meeting I have attended. Gerta Keller and co-workers, as well as others,
have presented a whole lot of data on microfossil ranges on either side
of the K-T boundary from sites world-wide, but I don't know about
>Just to put this in: I do think the K/T impact (which was probably
>Chixculub, if the age data confirm such a date) was resonsible for
>the terminal Cretaceous extinctions. However, the "rock dropping
>establishment" (rde) has refused to acknowledge the paleontological
>data of other extinction events prior to the K/T boundary.
There has been much discussion recently of the Signor-Lipps effect near
the K-T boundary, especially with respect to ammonites and microfossils.
Some statistical studies, presented last November, I believe, have
verified its existence in a portion of the data. Sorry I can't be more
Norman R. King tel: (812) 464-1794
Department of Geosciences fax: (812) 464-1960
University of Southern Indiana
8600 University Blvd.
Evansville, IN 47712 e-mail: firstname.lastname@example.org