[meteorite-list] a definitive result -- "No evidence of nanodiamonds in Younger Dryas sediments to support an impact event, " Tyrone L Daulton, Nicholas Pinter, Andrew C Scott, "Proceedings of the National Academy of Sciences": Rich Murray 2010.08.30

From: Rich Murray <rmforall_at_meteoritecentral.com>
Date: Mon, 30 Aug 2010 21:35:23 -0600
Message-ID: <1E3F1B9485044BF3B57278BAC8B5726F_at_ownerPC>

a definitive result -- "No evidence of nanodiamonds in Younger Dryas
sediments to support an impact event," Tyrone L Daulton, Nicholas Pinter,
Andrew C Scott, "Proceedings of the National Academy of Sciences": Rich
Murray 2010.08.30
http://rmforall.blogspot.com/2010_08_01_archive.htm
Monday, August 30, 2010
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[ Rich Murray: However and nevertheless -- since widespread ice comet
fragment air bursts probably caused relatively milder ground shocks, there
remains research opportunities re blasted and melted ground rocks and their
surface coatings, as proposed by Dennis Cox and others.

http://craterhunter.wordpress.com/ ]


http://chinese.eurekalert.org/en/pub_releases/2010-08/aaft-sif082710.php

No nanodiamonds at end of last ice age

Nanodiamonds in sediments, used by some to argue that the last ice age was
ended by comet strikes, may instead be microscopic graphite, according to a
study.

Article #10-03904: "No evidence of nanodiamonds in Younger Dryas sediments
to support an impact event," by Tyrone Daulton, Nicholas Pinter, and Andrew
Scott, "Proceedings of the National Academy of Sciences"

MEDIA CONTACT:
Tyrone L. Daulton, Center for Materials Innovation,
Washington University in St. Louis, St. Louis, MO;
tel: 314-935-4537; e-mail: tdaulton at physics.wustl.edu;


http://www.sciencedaily.com/releases/2010/08/100830152530.htm

[ same article as below ]

Science News

Impact Hypothesis Loses Its Sparkle: Shock-Synthesized Diamonds Said to
Prove Catastrophic Impact Killed Off N. American Megafauna Can't Be Found
ScienceDaily (Aug. 30, 2010)

Story Source:
The above story is reprinted (with editorial adaptations by ScienceDaily
staff) from materials provided by Washington University in St. Louis, via
EurekAlert!, a service of AAAS.

http://esciencenews.com/articles/2010/08/30/impact.hypothesis.loses.its.sparkle

Impact hypothesis loses its sparkle

Published: Monday, August 30, 2010 - 14:29 in Paleontology & Archaeology

Tyrone Daulton, photo

About 12,900 years ago, a sudden cold snap interrupted the gradual warming
that had followed the last Ice Age. The cold lasted for the 1,300-year
interval known as the Younger Dryas (YD) before the climate began to warm
again. In North America, large animals known as megafauna, such as mammoths,
mastodons, saber-tooth tigers and giant short-faced bears, became extinct.
The Paleo-Indian culture known as the Clovis culture for distinctively
shaped fluted stone spear points abruptly vanished, eventually replaced by
more localized regional cultures.

What had happened?

One theory is that either a comet airburst or a meteor impact somewhere in
North America set off massive environmental changes that killed animals and
disrupted human communities.

In sedimentary deposits dating to the beginning of the YD, impact proponents
have reported finding carbon spherules containing tiny nano-scale diamonds,
which they thought to be created by shock metamorphism or chemical vapor
deposition when the impactor struck.

The nanodiamonds included lonsdaleite, an unusal form of diamond that has a
hexagonal lattice rather than the usual cubic crystal lattice. Lonsdaleite
is particularly interesting because it has been found inside meteorites and
at known impact sites.

In the August 30 issue of the Proceedings of the National Academy of
Sciences, a team of scientists led by Tyrone Daulton, PhD, a research
scientist in the physics department at Washington University in St. Louis,
reported that they could find no diamonds in YD boundary layer material.

Daulton and his colleagues, including Nicholas Pinter, PhD, professor of
geology at Southern Illinois University In Carbondale and Andrew C. Scott,
PhD, professor of applied paleobotany of Royal Holloway University of
London, show that the material reported as diamond is instead forms of
carbon related to commonplace graphite, the material used for pencils.

"Of all the evidence reported for a YD impact event, the presence of
hexagonal diamond in YD boundary sediments represented the strongest
evidence suggesting shock processing," Daulton, who is also a member of
WUSTL's Center for Materials Innovation, says.

However, a close examination of carbon spherules from the YD boundary using
transmission electron microscopy by the Daulton team found no nanodiamonds.
Instead, graphene- and graphene/graphane-oxide aggregates were found in all
the specimens examined (including carbon spherules dated from before the YD
to the present). Importantly, the researchers demonstrated that previous YD
studies misidentified graphene/graphane-oxides as hexagonal diamond and
likely misidentified graphene as cubic diamond.

The YD impact hypothesis was in trouble already before this latest finding.
Many other lines of evidence -- including: fullerenes, extraterrestrial
forms of helium, purported spikes in radioactivity and iridium, and claims
of unique spikes in magnetic meteorite particles -- had already been
discredited. According to Pinter, "nanodiamonds were the last man standing."

"We should always have a skeptical attitude to new theories and test them
thoroughly," Scott says, "and if the evidence goes against them they should
be abandoned."

Source: Washington University in St. Louis

http://www.pnas.org/content/early/recent

Physical Sciences - Geology:
Tyrone L. Daulton, Nicholas Pinter, and Andrew C. Scott
No evidence of nanodiamonds in Younger?Dryas sediments to support an impact
event
PNAS published ahead of print August 30, 2010, doi:10.1073/pnas.1003904107
Abstract Full Text (PDF) Supporting Information $ 10 purchase

Published online before print August 30, 2010,
doi: 10.1073/pnas.1003904107
Abstract
Full Text (PDF)
Supporting Information

http://www.pnas.org/content/early/2010/08/26/1003904107.abstract

No evidence of nanodiamonds in Younger?Dryas sediments to support an impact
event
Tyrone L. Daulton a,1, Nicholas Pinter b, and Andrew C. Scott c
Author Affiliations

a Department of Physics and Center for Materials Innovation, Washington
University in St. Louis, St. Louis, MO 63130;
b Department of Geology, Southern Illinois University, Carbondale, IL 62901
[ Nicholas Pinter npinter at geo.siu.edu; 618-453-3351 Geology-SIUC, Professor,
Carbondale ];
and
c Department of Earth Sciences, Royal Holloway University of London, Egham,
Surrey TW20 OEX, United Kingdom

[ Prof Andrew C Scott,
BSc, PhD & DSc (London)
Professor of Applied Palaeobotany
Office, Queen's Building, Room 238
1st year: communication skills
2nd year: Stratigraphy, Sedimentology and Earth History
3rd Year: Advanced Palaeontology, Advanced Sedimentology, Communication
skills
4th Year: Coal Geology, Terrestrial Palaeoecology, Climate Change, Ancient
Climates, Independent Project supervisor
E-mail a.scott at es.rhul.ac.uk;
Telephone +44 (0) 1784 443608 Facsimile +44 (0) 1784 471780
Administration Duties
Address Department of Earth Sciences
Royal Holloway University of London
Egham, Surrey, TW20 0EX, UK ]

Edited by Mark H. Thiemens, University of California at San Diego, La Jolla,
CA,
and approved July 27, 2010 (received for review March 24, 2010)
[ Thiemens, Mark H. (858)534-6732
CHEM & BIOCHEM mthiemens at ucsd.edu; Professor, 0356

Abstract

The causes of the late Pleistocene megafaunal extinctions in North America,
disappearance of Clovis paleoindian lithic technology, and abrupt
Younger-Dryas (YD) climate reversal of the last deglacial warming in the
Northern Hemisphere remain an enigma.
A controversial hypothesis proposes that one or more cometary
airbursts/impacts barraged North America ?12,900 cal yr B.P. and caused
these events.
Most evidence supporting this hypothesis has been discredited except for
reports of nanodiamonds (including the rare hexagonal polytype) in
B?lling-?llerod-YD-boundary sediments.
The hexagonal polytype of diamond, lonsdaleite, is of particular interest
because it is often associated with shock pressures related to impacts where
it has been found to occur naturally.
Unfortunately, previous reports of YD-boundary nanodiamonds have left many
unanswered questions regarding the nature and occurrence of the
nanodiamonds.
Therefore, we examined carbon-rich materials isolated from sediments dated
15,818 cal yr B.P. to present (including the B?lling-?llerod-YD boundary).
No nanodiamonds were found in our study.
Instead, graphene- and graphene/graphane-oxide aggregates are ubiquitous in
all specimens examined.
We demonstrate that previous studies misidentified graphene/graphane-oxide
aggregates as hexagonal diamond and likely misidentified graphene as cubic
diamond.
Our results cast doubt upon one of the last widely discussed pieces of
evidence supporting the YD impact hypothesis.

archaeology paleoclimate Quaternary extinctions carbon spherules fungal
sclerotia

Footnotes

1 To whom correspondence should be addressed.
E-mail: tdaulton at physics.wustl.edu;
Author contributions: T.L.D., N.P., and A.C.S. designed research, performed
research, analyzed data, and wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at
www.pnas.org/lookup/suppl/doi:10.1073/pnas.1003904107/-/DCSupplemental
_______________________________________________


3 times more downward energy from directed force of meteor airburst
in 3D simulations by Mark B. E. Boslough, Sandia Lab 2007.12.17:
Rich Murray 2010.08.30
http://rmforall.blogspot.com/2010_08_01_archive.htm
Monday, August 30, 2010
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excellent Google Earth and ground views of shallow oval craters worldwide,
Pierson Barretto: Rich Murray 2010.08.22
http://rmforall.blogspot.com/2010_08_01_archive.htm
Sunday, August 22, 2010
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Rich Murray, MA
Boston University Graduate School 1967 psychology,
BS MIT 1964, history and physics,
1943 Otowi Road, Santa Fe, New Mexico 87505
505-501-2298 rmforall at comcast.net

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Received on Mon 30 Aug 2010 11:35:23 PM PDT