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

[MEM]

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.