[meteorite-list] Columbian Impact Structure (??) and Deccan Basalts was “Multiple Impact and 73P

[Paul]

In “Multiple Impact and 73P(was..More Evidence 
Chicxulub..)”, MexicoDoug at aol.com wrote

>Sterling W. writes: 
<< Keller-Harting get lots of press, but nobody 
<<is convinced by them but them... >> 
>
>Hola Sterling, 
>
>The idea that multiple impacts ocurred doesn't 
>seem to far fetched, and we can basically thank 
>them for introducing it as potentially more viable 
>and consistent based on top-notch fieldwork, not 
>just astronomical mullings.”

Columbian Impact Structure ??

This discussion reminded me a geologic structure, which
was found in seismic surveys made for oil and gas 
exploration, lying beneath the Columbian continental
shelf. It was a huge, possibly larger than Chicxulub, 
circular stucture, which was a candidate for the K/T
impact site, until it was found. Once Chicxulub was
found and published, it seems to have been completely
forgotten. Does anyone know if anything had ever been
published on it? Might this still be an alternate possibility 
for the K/T killer?

The Deccan Flood Basalts, An Additional Complication

To further complicate the K/T boundary controversy,
there are these findings and interpretations:

India’s Smoking Gun: Dino-Killing Eruptions 
Geological Society of America Press Release, 9 
August 2005 

http://www.geosociety.org/news/pr/05-27.htm

The abstract stated:

“In fact, most mass extinctions over the past 300 million 
years have coincided with large volcanic events, said 
Chenet. The general rule is that massive volcanism 
like the Deccan Traps correlates with all major mass 
extinctions in Earth's history, she said.”

Another article is “Volcanic prepping for dinosaur 
extinction” from the October 2005 Geotimes at:

http://www.agiweb.org/geotimes/oct05/NN_volcextinction.html

The abstract discussed in the above articles is: 

Chenet, A.-L. Courtillot, V., Fluteau, F., Besse, J., 
Subbarao, K. V., Khadri, S., Bajpai, S., and Jay, A., 2005, 
Magnetostratigraphy of the Upper Formations of the 
Deccan Traps: an Constraint on the Timing of the 
Eruptive Sequence. Session no. T9. Large Igneous 
Provinces: Their Biotic, Climatic, and Oceanic Impact, 
Earth System Processes 2 Meeting, August 8-11, 2005. 
Calgary, Alberta. 

http://gsa.confex.com/gsa/2005ESP/finalprogram/abstract_88502.htm

I find it fascinating that there seems to exist a far better 
correlation between eruption of massive flood basalts 
and mass extinctions than there is between impact 
events and mass extinctions. This is discussed in an 
interesting abstract:

Courtillot, V., and Thordarson, T., 2005, Flood basalts 
appear to be the main cause of biological mass 
extinctions in the Phanerozoic. Geophysical Research 
Abstracts, Vol. 7, 11196, 2005 
SRef-ID: 1607-7962/gra/EGU05-A-11196

http://meetings.copernicus.org/egu2005/download/EGU05-J-11196-1.pdf

The who, what, and when of the K/T extinction event is
far from a settled matter.

Best 

Paul


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