Ocean Acidification and the Permian and Triassic Extinctions

["Paul H." <oxytropidoceras@cox.net>]

Asteroid impacts are not the only possible cause for the Permian 
and Triassic-Jurassic 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/ 
 
âCompromise 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.â 
 
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 
 
âGlobal 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.â 
 
3. Hautmann, M., 2004, Effect of End-Triassic CO2 maximum 
on carbonate sedimentation and marine mass extinction. 
Facies. vol. 50, pp. 257â261. 
http://www.springerlink.com/content/ajvptjvenfvte5ck/ 
 
âBesides 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.â 
 
4. Hautmann, M., M., J. Benton, and A. Tomasovych, 2008, 
Catastrophic ocean acidification at the TriassicâJurassic 
boundary. Neues Jahrbuch fÃr Geologie und PalÃontologie 
Abhandlungen. vol. 249, pp. 119â127. 
 
"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 
 
âour results favor genesis as a submarine dissolution 
surface resulting from ocean acidification during the 
end-Permian extinction.â 
 
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 
 
âMass extinction events, many of which may be caused by 
rapid global changes in temperature and/or pCO2, represent 
major intervals of turnover.â 
 
Yours, 
 
Paul H.