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

[Paul]

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these outcrops have been retracted and the reports of helium-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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