Vulcanism and the Late Triassic Mass Extinction

Compound-specific carbon isotopes from Earth’s largest flood basalt eruptions directly linked to the end-Triassic mass extinction

1. Jessica H. Whiteside (a,1)
2. Paul E. Olsen (b,1)
3. Timothy Eglinton (c)
4. Michael E. Brookfield (d)
5. Raymond N. Sambrotto (e)


a. Department of Geological Sciences, Brown University, Box 1846, Providence, RI 02912;

b. Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964;

c. Department of Marine Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543;

d. Institute of Earth Sciences Academia Sinica, Nankang, Taipei 11529, Taiwan; and

e. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964

1. To whom correspondence may be addressed. E-mail: Jessica_Whiteside@Brown.edu or polsen@ldeo.columbia.edu.


Abstract:

A leading hypothesis explaining Phanerozoic mass extinctions and associated carbon isotopic anomalies is the emission of greenhouse, other gases, and aerosols caused by eruptions of continental flood basalt provinces. However, the necessary serial relationship between these eruptions, isotopic excursions, and extinctions has never been tested in geological sections preserving all three records. The end-Triassic extinction (ETE) at 201.4 Ma is among the largest of these extinctions and is tied to a large negative carbon isotope excursion, reflecting perturbations of the carbon cycle including a transient increase in CO2. The cause of the ETE has been inferred to be the eruption of the giant Central Atlantic magmatic province (CAMP). Here, we show that carbon isotopes of leaf wax derived lipids (n-alkanes), wood, and total organic carbon from two orbitally paced lacustrine sections interbedded with the CAMP in eastern North America show similar excursions to those seen in the mostly marine St. Audrie’s Bay section in England. Based on these results, the ETE began synchronously in marine and terrestrial environments slightly before the oldest basalts in eastern North America but simultaneous with the eruption of the oldest flows in Morocco, a CO2 super greenhouse, and marine biocalcification crisis. Because the temporal relationship between CAMP eruptions, mass extinction, and the carbon isotopic excursions are shown in the same place, this is the strongest case for a volcanic cause of a mass extinction to date.

And the commentary from Rampino.

Could someone send these to me? For some reason the Lab has lost its subscription to PNAS, of all goofy things.

anzha el-why-you at gmail dot com.

thanx.