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Re: extinction



On Wed, Jan 14, 2004 at 07:31:30PM -0500, Dewey M. McLean scripsit:
> In 1986, Olmez, Finnegan, and Zoller published a paper titled "Iridium
> emissions from Kilauea volcano" (Journal of Geophysical Research,
> 1986).  Following is a direct quotation from the paper:
> 
> "...Kilauea is a small volcano with insignificant eruptions....To
> estimate the importance for the mass extinction hypothesis, one must
> consider eruptions of a much larger scale, such as those...65 m.y.
> ago. One such eruption has been discussed by McLean [1982], who
> believes that the Deccan Traps basalts were a likely candidate....The
> Deccan probably did not occur on a short time scale, but let us
> estimate the quantity of Ir that could be emitted if the emissions
> were Kilauea-like in nature. Since approximately 10 x 10^6 km^3 of
> magma were emitted by the Deccan, the Ir emissions would be expected
> to be of the order of 30,000 tons, a little less than the mass
> believed to be contained in the KT boundary layer."

How do you go from the million or so years of intermittent
Deccan eruptions to the neat global iridium anomaly?

A number of _diffuse_ iridium enrichment layers would make sense; I
can't see how a narrow, concentrated band of iridium can be explained by
long term flood basalt volcanism, nor how a fluoridated gas transport
mechanism could result in macroscopic particles of metallic iridium being
deposited.

-- 
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