Younger Dryas - likely the result of meteor impact


by jim mcnamara
Tags: dryas, impact, meteor, result
jim mcnamara
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Sep10-13, 07:09 PM
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Origin and provenance of spherules and magnetic grains at the Younger Dryas boundary
Yingzhe Wu, Mukul Sharma, Malcolm A. LeCompte, Mark N. Demitroff, and Joshua D. Landis
PNAS 2013 ; published ahead of print September 5, 2013, doi:10.1073/pnas.1304059110
From the pnas.org overview:
Significance
This study ties the spherules recovered in Pennsylvania and New Jersey to an impact in Quebec about 12,900 y ago at the onset of Younger Dryas. Our discovery resulted from an exhaustive search that examined the question of whether there is any evidence of extraterrestrial platinum group metals present in the bulk sediments, magnetic grains, and spherules recovered from the Younger Dryas boundary (YDB). We find that the spherules are likely quenched silicate melts produced following the impact at the YDB. The source of spherule osmium, however, is likely terrestrial and not meteorite derived.
The takeaway is that a large meteor impact in Quebec showered a very large area in Northeastern North America with hot debris. The debris is at the exact boundary of the onset of the Younger Dryas. If this impact did not entirely cause the Younger Dryas cooling, it certainly is the most likely major player in the event. (My interpretation).

Mukul Sharma, one of the researchers, said as much in an article earlier:
http://www.theregister.co.uk/2013/09...climate_shift/
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Greg Bernhardt
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Nov30-13, 09:07 PM
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Interesting, thanks for sharing Jim!


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