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Saturday, 22 December 2007

Coal Methane Contributed Late Permian Extinctions ????

Coal Methane Contributed Late Permian Extinctions ????

Paul bristolia at yahoo.com
Fri Dec 21 16:23:22 EST 2007

Dear friends,

There is an interesting paper about how coal methane
might have contributed to Late Permian extinctions.

It is:

Retallack, G. J., and A. H. Jahren. 2007, Methane Release
from Igneous Intrusion of Coal during Late Permian
Extinction Events. The Journal of Geology. vol. 116, pp. 1–20

http://www.journals.uchicago.edu/doi/abs/10.1086/524120

In part the abstract read:

“Unusually large and locally variable carbon isotope excursions
coincident with mass extinctions at the end of the Permian
Period (253 Ma) and Guadalupian Epoch (260 Ma) can be
attributed to methane outbursts to the atmosphere. .... On
paleogeographic maps, the most marked carbon isotope
excursions form linear arrays back to plausible methane
sources: end-Permian Siberian Traps and Longwood-Bluff
intrusions of New Zealand and end-Guadalupian Emeishan
Traps of China. Intrusion of coal seams by feeder dikes to
flood basalts could create successive thermogenic methane
outbursts of the observed timing and magnitude, ...
Methane released by fracturing and heating of coal during
intrusion of large igneous provinces may have been a
planetary hazard comparable with bolide impact.”

This paper concluded:

“Addition of the end-Guadalupian case to the better known
end-Permian, end-Triassic, and end-Cretaceous cases
makes coincidence less likely, and copious generation of
methane by intrusion of coals supplies ample killing power.
Like meteorite and comet impacts, thermogenic methane
outbursts may have been significant hazards to life on Earth.”

Yours,

Paul H.

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