[meteorite-list] Coal Methane Contributed Late Permian Extinctions ????

[Paul]

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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