[meteorite-list] Micrometeorite impacts in Beringian mammoth tusks and a bison skull (large photos) abstract, RB Firestone, A West, JT Hagstrum, et al, AGU Fall Meeting 2007 Dec 10-14, more Dec 16, 2009: Rich Murray 2009.12.03

From: Rich Murray <rmforall_at_meteoritecentral.com>
Date: Thu, 3 Dec 2009 23:29:15 -0700
Message-ID: <71F664A273B04B029334A7362C927ED8_at_ownerPC>

Micrometeorite impacts in Beringian mammoth tusks and a bison skull (large
photos) abstract, RB Firestone, A West, JT Hagstrum, et al, AGU Fall Meeting
2007 Dec 10-14, more Dec 16, 2009: Rich Murray 2009.12.03
http://rmforall.blogspot.com/2009_12_01_archive.htm
Thursday, December 3, 2009
http://groups.yahoo.com/group/astrodeep/message/33
____________________________________________________


http://ie.lbl.gov/mammoth/impact_old.html

Micrometeorite Impacts in Beringian Mammoth Tusks
and a Bison Skull
AGU Fall Meeting, 10-14 December 2007, San Francisco, CA
Richard B. Firestone, Lawrence Berkeley National Laboratory,
Berkeley, CA, 94720, United States
Allen West, GeoScience Consulting,
Dewey, AZ, 86327, United States
Zsolt Stefanka and Zsolt Revay, Institute of Isotopes,
Budapest, Hungary
Jonathon T. Hagstrum, U.S. Geological Survey,
345 Middlefield Road MS 937,
Menlo Park, CA 94025, United States

Abstract:
We have discovered what appear to be micrometeorites imbedded
in seven Alaskan Mammoth tusks and a Siberian bison skull.
The micrometeorites apparently shattered on impact
leaving 2-5 mm hemispherical debris patterns
surrounded by carbonized rings.
Multiple impacts are observed on only one side of the tusks and
skull consistent with the micrometeorites
having come from a single direction.
The impact sites are strongly magnetic
indicating significant iron content.
We analyzed several imbedded micrometeorite fragments
from both tusks and skull with
Laser Ablation Inductively-Coupled Plasma Mass Spectrometry
(LA-ICP-MS) and X-ray Fluorescence (XRF).
These analyses confirmed the high iron content and a uniform
composition highly enriched in nickel and depleted in titanium.
The Fe/Ni and Fe/Ti ratios are comparable to urelite meteorites
and are unlike any terrestrial sources.
Prompt Gamma-ray Activation Analysis (PGAA) of a
micrometeorite extracted from the bison skull indicated
it contained ~0.4 mg of iron, in agreement
with a micrometeorite ~1 mm in diameter.
Several tusks have an average radiocarbon age of ~33 ka.
This age coincides with sudden increases in global radiocarbon
~35 ka ago a and 10Be ~32 ka ago b,
the Mono Lake geomagnetic excursion ~34 ka ago c, and
significant declines in Beringian bison, horse, brown bear, and
mammoth populations and genetic diversity <36 ka ago d.
The bison skull shows evidence of new bone growth over
the micrometeorite impact sites indicating the animal survived
the bombardment and is dated at ~26 ka
which is younger than the tusks.
This age is consistent with exposure of the bison to an enriched
source of radiocarbon following the impact.
It appears likely that the impacts, cosmogenic isotope increases,
magnetic excursion, and population declines are related events
(Occam's razor), although their precise nature
remains to be determined.

a K. Hughen, et al.,
Science 303, 202-207 (2004).
b L.R. McHargue, P.E. Damon, & D.J. Donahue,
Geophys. Res. Lett. 22, 659-662 (1995).
c J.E.T. Channell,
Earth Planet. Sci. Lett. 244, 379-393 (2006).
d I. Barnes, et al,
Current Biology 17, 1-4 (2007).

Tusk Photos, click on image to enlarge

Figure 1. Embedded iron particles surrounded by carbonized rings
in the bark of an Alaskan Mammoth tusk.
The inclusions all attract a magnet suspended nearby.
Note that the inclusion on the side ripped through the tusk.

Figure 2. Numerous impact sites are seen on another Alaskan tusk.

Figure 3. Siberian bison skull containing numerous iron particle
impact sites that stongly attract a magnet.

Figure 4. Close-up of impact site and side x-ray through the tusk
indicating that the particle exploded forming a hemispherical
debris pattern.

Figure 5. Siberian bison skull with embedded iron particles.
Significant skull growth around the particles indicated that
the bison survived the impact.

Figure 6. Top x-ray of tusk particles show that they penetrate
the tusk.

Figure 7. More tusk particles with characteristic burn ring.

Figure 8. Closeup view of an iron particle embedded
in a bison skull.

Figure 9. Additional tusk particles.

Figure 10. Photograph of the surface pit from a micrometeorite
on the vycor window of the MA-9 Mercury spacecraft.
Note the similarities to the mammoth tusk impact pits.

Richard B. Firestone, e-mail: rbf at lbl.gov
Ernest O. Lawrence Berkeley National Laboratory
MailStop 88-R0192
1 Cyclotron Road, Berkeley, CA 94720
Phone: 510-486-7646 Fax: 510-486-5757


AGU Fall Meeting 2009
ID# PP31D-1385
Location: Poster Hall (Moscone South)
Time of Presentation:
Dec 16 8:00 AM - 12:20 PM

Beringian Megafaunal Extinctions at ~37 ka B.P.:
Do Micrometeorites Embedded in Fossil Tusks and Skulls
Indicate an Extraterrestial Precursor to the Younger Dryas Event?
J. T. Hagstrum 1; R. B. Firestone 2; A. West 3
1. U.S. Geological Survey, Menlo Park, CA, USA.
2. Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
3. GeoScience Consulting, Dewey, AZ, USA.

Studies of Late Pleistocene megafaunal fossils and their ancient
DNA from Beringia
(eastern Siberia, Alaska, and the emerged Bering Strait) indicate
sharp declines in steppe bison population diversity and
horse body size, extinction of the Alaskan wild ass, and
local extinctions of brown bear and woolly mammoth genetic
lines beginning at about 37 ka B.P.
Beringia is also well known for its remarkably preserved
Late Pleistocene frozen animal mummies.
14C ages of these mummies are bimodally distributed, having peaks
coincident with the earlier ~37 ka B.P., and ~13 ka B.P.
Younger Dryas, onset extinction events.
Associated with the ~37 ka B.P. event are, for example, the
Berezovka mammoth, headless Selerikan horse, steppe bison
"Blue Babe", and baby mammoths "Dima" and "Lyuba".
Analyses of these and other mummies indicate that they died
instantly, in mostly healthy condition, with gut contents and
high fat reserves indicative of a late summer to autumn season.
An assortment of uneaten limbs and other body parts from a
variety of species have also been found.
Uniformitarian death scenarios inadequately account for the lack
of evidence of normal predation and scavenging.
Extensive internal injuries (e.g. large bone fractures, hemorrhaging)
and apparent rapid burial of the mummies also indicate that
something truly unusual happened at the time of these
extinction events.
We have discovered what appear to be micrometeorites
embedded in seven Alaskan mammoth tusks and a Siberian bison
skull acquired from commercial sources.
14C ages for five of these fossils have a weighted mean age of
33 ? 2 ka B.P.
Laser ablation ICP-MS and XRF analyses of the particles indicate
high Fe contents with compositions enriched in Ni and depleted in
Ti, similar to Fe meteorites and unlike any natural terrestrial sources.
Microprobe analyses of a Fe-Ni sulfide grain from tusk 2 also show
that it contains between 3 and 20 weight percent Ni.
SEM images and XRF analyses of a bison skull fragment show
sharp-edged channels (~0.1 mm across) containing Fe sulfide
material with botryoidal texture that appears to have cooled from
a molten state.
Multiple embedded particles are observed on only one side of the
tusk and skull fossils, consistent with micrometeorites coming
from a single direction.
During recent visits to natural history collections in Berkeley, CA,
New York City, and London, UK, embedded Fe-rich particles
were uncovered in an additional 13 Alaskan bison, horse, and
musk ox skulls, and a Siberian Elasmotherium skull.
We propose that the extinctions, embedded micrometeorites, and
frozen mummies contemporaneous with the ~37 ka B.P. event all
resulted from an airburst (similar to the 1908 Tunguska event), or
series of airbursts, across Beringia due to the breakup and deep
atmospheric penetration of an Fe-Ni asteroid.
The micrometeorites can be envisioned as shrapnel traveling within
the blast wave(s).
The instantaneous deaths, internal injuries, and possible traumatic
amputations and decapitations in megafaunal mummies are
consistent with blast injuries related to such a catastrophic scenario.

Contact Information
Jonathan T. Hagstrum, Menlo Park, California, USA,
94025-3561 click here to send an email
 jhag at usgs.gov AGU-FM09: Question regarding PP31D-1385:
ScholarOne Abstracts? (patent #7,257,767 and #7,263,655).
? ScholarOne, Inc., 2009. All Rights Reserved.
ScholarOne Abstracts and ScholarOne are registered trademarks
of ScholarOne, Inc.
____________________________________________________


exact Carolina Bay crater locations, RB Firestone, A West, et al, two
YD reviews, 2008 June, 2009 Nov, also 3 upcoming abstracts:
Rich Murray 2009.11.14
http://rmforall.blogspot.com/2009_11_01_archive.htm
Saturday, November 14, 2009
http://groups.yahoo.com/group/astrodeep/message/31

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

http://groups.yahoo.com/group/AstroDeep/messages

http://RMForAll.blogspot.com new primary archive

http://groups.yahoo.com/group/aspartameNM/messages
group with 143 members, 1,590 posts in a public archive

http://groups.yahoo.com/group/aspartame/messages
group with 1209 members, 23,973 posts in a public archive

http://groups.yahoo.com/group/rmforall/messages

participant, Santa Fe Complex www.sfcomplex.org
____________________________________________________
Received on Fri 04 Dec 2009 01:29:15 AM PST