[meteorite-list] Ocean Acidification and Permain and Triassic Extinctions

From: Paul H. <oxytropidoceras_at_meteoritecentral.com>
Date: Fri, 18 Dec 2009 8:06:09 -0600
Message-ID: <20091218090609.QFEFV.224358.imail_at_eastrmwml38>

Asteroid impacts are not the only possible cause for the Permian
and Triassic extinctions. Some recent papers on one possible cause.

1. Saunders, A., and M. Reichow, 2009, The Siberian Traps
and the End-Permian mass extinction: a critical review.
Chinese Science Bulletin. vol. 54, no. 1, pp. 20-37.
http://www.springerlink.com/content/1743222152769702/

?Compromise of the carbon sequestration systems (by
curtailment of photosynthesis, destruction of biomass,
and warming and acidification of the oceans) probably
led to rapid atmospheric CO2 build-up, warming, and
shallow-water anoxia, leading ultimately to mass extinction.?

2. Knoll, A. H., R. K. Bambach, J. L. Payne, S. Prussa and
Woodward W. Fischer, 2007, Paleophysiology and
end-Permian mass extinction. Earth and Planetary
Science Letters. vol. 256, no. 3-4, pp. 295-313.
http://dx.doi.org/10.1016/j.epsl.2007.02.018

?Global warming, anoxia, and toxic sulfide probably all
contributed to end-Permian mass mortality, but
hypercapnia (physiological effects of elevated PCO2)
best accounts for the selective survival of marine
invertebrates.?

3. Hautmann, M., 2004, Effect of End-Triassic CO2 maximum
on carbonate sedimentation and marine mass extinction.
Facies. vol. 50, pp. 257?261.
http://www.springerlink.com/content/ajvptjvenfvte5ck/

?Besides the frequently cited climatic effect of enhanced
carbon dioxide, lowering the saturation state of sea water
with respect to calcium carbonate was an additional driving
force of the end-Triassic mass extinction, which chiefly
affected organisms with thick aragonitic or high-magnesium
calcitic skeletons. Replacement of aragonite by calcite, as
found in the shells of epifaunal bivalves, was an evolutionary
response to this condition.?

4. Hautmann, M., M., J. Benton, and A. Tomasovych, 2008,
Catastrophic ocean acidification at the Triassic?Jurassic
boundary. Neues Jahrbuch f?r Geologie und Pal?ontologie
Abhandlungen. vol. 249, pp. 119?127.

"Using carbon isotopes as a geochemical marker, we found
that the onset of the CO2 emissions coincided with an
interruption of carbonate sedimentation in palaeogeographically
distant regions, suggesting that hydrolysis of CO2 led to
a short but substantial decrease of seawater pH that
slowed down or inhibited precipitation of calcium
carbonate minerals. The cessation of carbonate sedimentation
correlates with a major marine extinction event, which
especially affected organisms with aragonitic or high-Mg
calcitic skeletons and little physiological control of
biocalcification."

5. Ryan, D., and D. Lehrann, 2009, Petrographic evaluation of
a Permian-Triassic erosion surface and implications for
causes of the end-Permian mass extinction. Geological Society
of America Abstracts with Programs, Vol 41, No. 4, p. 17
http://gsa.confex.com/gsa/2009NC/finalprogram/abstract_156104.htm

?our results favor genesis as a submarine dissolution
surface resulting from ocean acidification during the
end-Permian extinction.?

6. Veron, J. E. N., 2008, Mass extinctions and ocean acidification:
biological constraints on geological dilemmas. Coral Reefs.
vol. 27, no. 3., pp. 459-472.
http://www.springerlink.com/content/085g2151l3nlt871/

7. Zhuravlev, A. Y.,* and R. A. Wood, 2009, Controls on
carbonate skeletal mineralogy: Global CO2 evolution and
mass extinctions. Geology. vol. 37, no. 12, pp. 1123-1126.
http://geology.gsapubs.org/content/37/12/1123.abstract

?Mass extinction events, many of which may be caused by
rapid global changes in temperature and/or pCO2, represent
major intervals of turnover.?

Yours,

Paul H.
Received on Fri 18 Dec 2009 09:06:09 AM PST