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C13: C12 Ratios...
Hey,
Bear with me, as this may be a bit off topic, but it is part of a much larger
picture.
Before the terrorist attacks of two weeks ago I was beginning an on-list
conversation on a possible Upper Pennsylvanian extinction event in Illinois. I
had a question of whether there was evidence for this event at other sites
around the world, or if it was localized.
As far as I can now tell, the event probably was localized. However, that is
assuming that there WAS an extinction event. The rocks certainly preserve what
appears to be a mass-death layer of brachiopods. But, this could simply be an
artifact of preservation.
In order to test whether or not this mass-death event may be real, I would like
to employ a little C13: C12 ratio test. Basically speaking, as far as I can
tell from my research, the ratio of C13 to C12 (sorry about the scripts) in
ideal carbon dioxide emitted from volcanoes is about 1:99 (of course, this can
vary, but it is the ideal ratio). Correct me if I'm wrong, please.
However, this ratio changes as this carbon dioxide is used by photosynthesizing
plants and algae. Organisms that photosynthesize prefer C12. Therefore, in
carbonate rock samples that were formed in an area of high life diversity, the
ratio of C13: C12 is higher.
I have two basic questions:
1) Would testing this ratio in a few samples of Upper Pennsylvanian limestone
be a good indicator of diversity (low ratio=less life, high ratio=more life)?
2) What would be the ratio of C13: C12 in an ideal sample of Paleozoic
limestone? By this, I mean a limestone that was formed when there was a
relatively high diversity of life.
Thanks for bearing with this. Have a nice weekend!
Steve
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Steve Brusatte-DINO LAND PALEONTOLOGY
SITE: http://www.geocities.com/stegob
ONLINE CLUB: http://clubs.yahoo.com/clubs/thedinolanddinosaurdigsite
WEBRING: http://home.wanadoo.nl/dinodata.net/
INTERNATIONAL LANGUAGE SITE: http://www.geocities.com/stegob/international.html
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