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| Titel |
Conditions for the formation and atmospheric dispersion of a toxic, heavy gas layer during thermal metamorphism of coal and evaporite deposits by sill intrusion |
| VerfasserIn |
Michael Storey, Robin K. S. Hankin |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250039960
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| Zusammenfassung |
| There is compelling evidence for massive discharge of volatiles, including toxic species, into
the atmosphere at the end of the Permian. It has been argued that most of the gases were
produced during thermal metamorphism of coal and evaporite deposits in the East Siberia
Tunguska basin following sill intrusion (Retallack and Jahren, 2008; Svensen et al., 2009).
The release of the volatiles has been proposed as a major cause of environmental and
extinction events at the end of the Permian, with venting of carbon gases and halocarbons to
the atmosphere leading to global warming and atmospheric ozone depletion (Svensen et al.,
2009)
Here we consider the conditions required for the formation and dispersion of toxic, heavier
than air, gas plumes, made up of a mixture of CO2, CH4, H2S and SO2 and formed during the
thermal metamorphism of C- and S- rich sediments. Dispersion models and density
considerations within a range of CO2/CH4 ratios and volatile fluxes and temperatures, for gas
discharge by both seepage and from vents, allow the possibility that following sill
emplacement much of the vast East Siberia Tunguska basin was - at least intermittently -
covered by a heavy, toxic gas layer that was unfavorable for life. Dispersion scenarios for
a heavy gas layer beyond the Siberian region during end-Permian times will be
presented.
REFERENCES
G. J. Retallack and A. H. Jahren, Methane release from igneous intrusion of coal
during Late Permian extinction events, Journal of Geology, volume 116, 1–20,
2008
H. Svensen et al., Siberian gas venting and the end-Permian environmental crisis, Earth and
Planetary Science Letters, volume 277, 490–500, 2009 |
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