[meteorite-list] Re: Does a Giant Crater Lie Beneach the Antarctic Ice?

From: Paul <bristolia_at_meteoritecentral.com>
Date: Wed Jun 7 00:07:12 2006
Message-ID: <20060606170813.60690.qmail_at_web36215.mail.mud.yahoo.com>

On June 4, 2006, Ron Baalke quoted

?http://www.nature.com/news/2006/060529/full/060529-11.html

Does a giant crater lie beneath the Antarctic ice?
Signs of an ancient impact could help to explain a mass
extinction. by Mark Peplow, nature.com,June 2, 2006"

In part, the article stated:

?An impact of that size should also have melted and
twisted nearby rock. Yet rocks in the Transantarctic
Mountains of the same age show no evidence of the
collision, says Jane Francis, a geologist also at the
University of Leeds. "That sequence has been worked
on before, and no one has found evidence to support
a massive impact like this," she says.?

This is an excellent point as there are complete stratigraphic
sections across the Permian-Triassic boundary exposed in
the Transantarctic Mountains and undisputed impact ejecta
and other evidence of a nearby impact of such a size is
completely lacking. The reports of shocked quartz from
these outcrops have been retracted and the reports of helium-
filled fullerenes, meteorite fragments, and other impact-
related debris are highly disputed. A full description of the
Permian-Triassic boundary and a discussion of the impact
ejecta reported from it can be found in:

Collinson, J. W., Hammer, W. R., Askin, R. A., and Elliot,
D. E., 2006, Permian-Triassic boundary in the central
Transantarctic Mountains, Antarctica. Geological Society
of America Bulletin. vol. 118, no. 5, pp. 747?763.
doi: 10.1130/B25739.1

http://www.gsajournals.org/gsaonline/?request=get-abstract&doi=10.1130%2FB25739.1

Yours,

Paul

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Received on Tue 06 Jun 2006 01:08:13 PM PDT