[meteorite-list] Antarctic Craters Reveal Strike

From: Marc D. Fries <m.fries_at_meteoritecentral.com>
Date: Fri Aug 20 10:09:33 2004
Message-ID: <1085.10.17.14.1.1093010895.squirrel_at_webmail.ciw.edu>

Howdy

   The date matches well, but not much else, and thats certainly not
enough to pitch all other findings out the window over. It does show
that the Earth was bombarded with good-sized impactors at a time when
we already know there were impacts, as the existance of the tektites
tells us in the first place. It doesn't clear up problems such as the
size distribution, which points to an impact event in SE Asia, or the
fact that the presumably farther-thrown Australites were partially
remelted by re-entry when those in Vietnam and the Phillipines were
not. This also points to an impact in SE Asia and is strong evidence
against a source impact in Antarctica. SE Asia is farther from
Antarctica than Australia, and if the source were Antarctica then it
should be the SE Asia tektites that were remelted; not the Australites.
   Sorry; even if the Antarctic strikes pan out, there's still a lot of
explaining to do if anyone wants to tie them to the tektite field. It
would be interesting to search for a compositional match between the
Antarctic impactors and the source of the SE Asia tektites, though.
Perhaps they were events that can be tied to a single disruption in the
asteroid belt.

My 2 cents,
MDF


> Hi, Everybody,
>
> Assuming that this first report is solid, is supported by followup
> research, everybody agrees on everything, yada, yada, this has potentially
> revolutionary, or at least upsetting, implications.
> Note the DATE of these huge impacts. Yes, boys and girls, it's almost
> perfect match for the best estimated date of the Australasian tektite
> event.
> So it would seem that decades of vain searching for a same-date impact
> crater in Thailand, Cambodia, drilling in the Tonle Sap, et cetera, was a
> big waste of time.
> Or are we going to insist that an invisible undiscovered crater in
> S.E.
> Asia is responsible for the Australasian tektite event when we have a 200
> mile crater in a field of craters in Antarctica at the right date? And
> right
> next door, too.
> Let's say we accept the obvious conclusion that such a huge impact
> event
> in Antarctica at the same time as the Australasian tektite event cannot be
> a
> "coincidence," and move the Antarctic craters up to number one contender
> for
> the cause of the Australasian tektite event.
> What does that do to the decades of theorizing, modeling, aerodynamic
> studies, and generally self-reinforcing thought that explains the
> variations
> in the tektites in the Australasian tektite strewn field (from Muong Nuong
> to Australites) on the basis of their distance from a supposed S.E. Asian
> impact when the impact is at the other end of the 10,000 mile long strewn
> field?
> Shoots it all to hell, is what it does.
> Even worse, every theorist with a theory license agrees that the
> source
> material for the formation of tektites is the surface rock of the Earth at
> the point of impact. That's SURFACE rock, NOT sub-surface rock, the
> Moldavites for example being explained by the composition of surface sand
> layers, which gave them the properties that set them apart from other
> tektites.
> OK, what's the surface rock of the Antarctic ICE sheet? Well, it's
> ice;
> there isn't any surface rock. It's ICE. How do you make a tektite out of
> ice? Beats me.
> The only source of rock is... the impactor itself. This, in turn,
> makes
> things a hundred times worse, because everybody agrees that tektites
> cannot
> be formed from any extraterrestial material that we know of: wrong
> elemental
> composition, wrong isotopic composition, and so forth.
> In fact, the further one moseys down the logic trail from the obvious
> and hard-to-escape acceptance of this immense crater field as the source
> of
> the Australasian tektite strewn field, the worse it gets. It strongly
> suggests that almost everything we think we know about tektites is wrong.
> Oh, no, how could that be? And us so smart and all...
>
>
> Sterling K. Webb
> -------------------------------------------------------------------------------------
>
> Of course, the first question is: how did they determine this date?
> What's the +/- of the date? Is it the same for all the craters? More
> details!
> -------------------------------------------------------------------------------------
>

-- 
Marc D. Fries, Ph.D.
Postdoctoral Research Associate
Carnegie Institution of Washington
Geophysical Laboratory
5251 Broad Branch Rd. NW
Washington, DC 20015
PH:  202 478 7970
FAX: 202 478 8901

Received on Fri 20 Aug 2004 10:08:15 AM PDT