Re: Clarification of impact event at K-T

[Paul <bristolia@yahoo.com>]

Re: Clarification of impact event at K-T

Dr. Thomas R. Holtz quoted and wrote:

>> The five craters are: Chicxulub (Yucatan, Mexico), 
>>Shiva (offshore western India), Small Point Maine 
>>(offshore Maine & Massachusetts),
>
>This has been featured in a few GSA talks, but I don't 
>know if it is written up. And as far as I recall, there 
>was no secure age data for it.

>From what I have seen, nothing has been formally written up 
about the alleged Small Point (Maine) âcraterâ except for the 
GSA abstracts. What I could find in GEOREF was:

1. Manzer, D., and D. H. Abbott, 2003, A large K/T crater in 
the Gulf of Maine? Abstracts with Programs - Geological
Society of America. vol. 35, no. 3, pp. 81
http://gsa.confex.com/gsa/2003NE/finalprogram/abstract_51410.htm

2. Abbott, D. H., and D. Manzer, 2003, Effects and implications 
of a proposed Gulf of Maine K/T impact. Abstracts with 
Programs - Geological Society of America, vol. 35, no. 3, pp. 15.
http://gsa.confex.com/gsa/2003NE/finalprogram/abstract_51447.htm

3. Possible Second Crater Linked to Dinosaur Extinction
http://starryskies.com/articles/2003/04/impact.html

âOther scientists are less optimistic that this is indeed
 an impact crater. David Kring of the Lunar and 
Planetary Laboratory at the University of Arizona. 
Insists that there is no evidence of an impact.â

4. Maine Crater Related to Dino-Killer Asteroid?
By Larry O'Hanlon, Discovery News, April 3, 2003
http://seti.sentry.net/archive/bioastro/2003/Apr/0045.html
http://www.mail-archive.com/meteorite-list@meteoritecentral.com/msg11328.html

There is a lack of any really solid evidence, which has been 
so far published, that this feature is an actual crater of any 
sort and, if it is a real crater, what it is age might be.

David Marjanovic ( http://dml.cmnh.org/2009Feb/msg00079.html  ) wrote:

>The Shiva "crater" is not a crater, however; Chatterjee just 
>interpreted a crater into a seafloor map without considering 
>what the geological evidence actually says and without 
>explaining why the shape has a corner

That is my impression also. There is a discussion of its highly 
disputed nature in âShiva: Another K-T impact?â by Leslie 
Mullen in Astrobiology magazine at:
http://www.astrobio.net/news/article1281.html

The Shiva Crater has advocated by Sankar Chatterjee in a number
of abstracts and short articles including:

Chatterjee, S., N. Guven, A. Yoshinobu, and R. Donofrio, 2003,
The Shiva Crater; implications for Deccan volcanism, India-
Seychelles rifting, dinosaur extinction, and petroleum entrapment 
at the K T boundary. Abstracts with Programs - Geological 
Society of America. vol. 35, no. 6, pp. 168
http://gsa.confex.com/gsa/2003AM/finalprogram/abstract_58126.htm

The alleged Shiva crater still has yet to make the Earth Impact 
Database at:

http://www.unb.ca/passc/ImpactDatabase/
http://www.unb.ca/passc/ImpactDatabase/CINameSort2.htm

Details and references about the Boltysh Impact Structure can be 
found at:

http://www.unb.ca/passc/ImpactDatabase/images/boltysh.htm

There, the age of  the Boltysh Impact Structure is given as 
65.17Â 0.64 millions years ago and being 24 km in diameter.

Yours,

Paul V. Heinrich
Baton Rouge, LA