[meteorite-list] Nanodiamonds Discovered in Greenland Ice Sheet, Contribute to Evidence for Cosmic Impact

From: MEM <mstreman53_at_meteoritecentral.com>
Date: Thu, 16 Sep 2010 00:46:55 -0700 (PDT)
Message-ID: <697617.98755.qm_at_web55208.mail.re4.yahoo.com>

I'm not sure if this made the list sorry if it is old news.
Elton

Nanodiamonds Discovered in Greenland Ice Sheet, Contribute to Evidence for
Cosmic Impact
ScienceDaily (Sep. 15, 2010) ? Nanosize diamonds have been discovered in the
Greenland ice sheet, according to a study reported by scientists in a recent
online publication of the Journal of Glaciology. The finding adds credence to
the controversial hypothesis that fragments of a comet struck across North
America and Europe approximately 12,900 years ago.

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"There is a layer in the ice with a great abundance of diamonds," said
co-author James Kennett, professor emeritus in the Department of Earth Science
at UC Santa Barbara. "Most exciting to us is that this is the first such
discrete layer of diamonds ever found in glacial ice anywhere on Earth,
including the huge polar ice sheets and the alpine glaciers. The diamonds are
so tiny that they can only be observed with special, highly magnifying
microscopes. They number in the trillions."
This discovery supports earlier published evidence for a cosmic impact event
about 12,900 years ago, Kennett explained. He said that the available evidence
in the Greenland ice is consistent with this layer being at or close to this
age, although further study is needed.
Researchers from the University of Maine led the expedition to Greenland in
2008. Co-authors on the study, besides Kennett and the team from Maine, include

scientists from many universities and research entities. James Kennett's son,
Douglas J. Kennett, of the University of Oregon, is one of the 21 scientists
who contributed to the report.
Last year, the Kennetts reported the discovery of nanosize diamonds in a layer
of sediment exposed on Santa Rosa Island, off the coast of Santa Barbara,
Calif. They published this information with numerous co-authors in two papers
last year in the Proceedings of the National Academy of Sciences and Science
magazine.
According to James Kennett, the Greenland results also contradict a recent
study questioning the presence of nanodiamonds in a layer of this age.
Kennett explained that the layer containing nanodiamonds on Santa Rosa Island,
as well as those in the Greenland ice sheet -- both supporting a cosmic impact
event -- appear to closely correspond to the time of the disappearance of the
Clovis culture, the earliest well-established and well-accepted human culture
living across North America. The event also corresponds with the time of
extinction of many large animals across North America, including mammoths,
camels, horses, and the saber tooth cat.
There is also evidence of widespread wildfires at that time, said Kennett. An
associated sharp climatic cooling called the Younger Dryas cooling is also
recorded widely over the northern hemisphere. This includes evidence found in
ocean-drilled sediments beneath the Santa Barbara Channel. The cause of this
cooling has long been debated as well as the cause of the animal extinctions and

human cultural shift.
A high proportion of the nanosize diamonds in the Greenland ice sheet exhibit
hexagonal mineral structure, and these are only known to occur on Earth in
association with known cosmic impact events, said Kennett. This layer of
diamonds corresponds with the sedimentary layer known as the Younger Dryas
Boundary, dating to 12,900 years ago.
James Kennett, former director of the Marine Science Institute at UCSB, is
considered by many of his peers to be an early founder of marine geology and
paleoceanography. He has specialized in analyzing sedimentary layers below the
ocean floor.
Received on Thu 16 Sep 2010 03:46:55 AM PDT