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Title: Micrometeorite Impacts in Beringian Mammoth Tusks and a Bison Skull

Abstract

We have discovered what appear to be micrometeorites imbedded in seven late Pleistocene Alaskan mammoth tusks and a Siberian bison skull. The micrometeorites apparently shattered on impact leaving 2 to 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 confirm the high iron content and indicate compositions highly enriched in nickel and depleted in titanium, unlike any natural terrestrial sources. In addition, electron microprobe (EMP) analyses of a Fe-Ni sulfide grain (tusk 2) show it contains between 3 and 20 weight percent Ni. Prompt gamma-ray activation analysis (PGAA) of a particle extracted from the bison skull indicates ~;;0.4 mg of iron, in agreement with a micrometeorite ~;;1 mm in diameter. In addition, scanning electron microscope (SEM) images and XRF analyses of the skull show possible entry channels containing Fe-rich material. The majority of tusks (5/7) have a calibrated weighted mean 14Cmore » age of 32.9 +- 1.8 ka BP, which coincides with the onset of significant declines<36 ka ago in Beringian bison, horse, brown bear, and mammoth populations, as well as in mammoth genetic diversity. It appears likely that the impacts and population declines are related events, although their precise nature remains to be determined.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
Nuclear Science Division
OSTI Identifier:
1023384
Report Number(s):
LBNL-4681E
TRN: US1105034
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Siberian Federal University. Engineering&Technologies; Journal Volume: 3; Journal Issue: 1; Related Information: Journal Publication Date: February, 2010
Country of Publication:
United States
Language:
English
Subject:
59; 54; 58; 37; 73; 79; ABLATION; ACTIVATION ANALYSIS; ANIMALS; ARCHAEOLOGICAL SPECIMENS; ELECTROMAGNETIC PULSES; ELECTRON MICROPROBE ANALYSIS; FLUORESCENCE; FOSSILS; GENETICS; IMAGES; IRON; LASERS; MASS SPECTROSCOPY; METEORITES; NICKEL; PLASMA; SKULL; SULFIDES; TITANIUM; global climate changes, megafauna, micrometeorites, multiple impacts, Siberian bison skull, Pleistocene Alaskan mammoth tusks, plasma mass spectrometry analyses, X-ray fluorescence analyses, electron microprobe analyses, gamma-ray activation analysis, scanning electron microscope images

Citation Formats

Hagstrum, Jonathon T., Firestone, Richard B, West, Allen, Stefanka, Zsolt, and Revay, Zsolt. Micrometeorite Impacts in Beringian Mammoth Tusks and a Bison Skull. United States: N. p., 2010. Web.
Hagstrum, Jonathon T., Firestone, Richard B, West, Allen, Stefanka, Zsolt, & Revay, Zsolt. Micrometeorite Impacts in Beringian Mammoth Tusks and a Bison Skull. United States.
Hagstrum, Jonathon T., Firestone, Richard B, West, Allen, Stefanka, Zsolt, and Revay, Zsolt. Wed . "Micrometeorite Impacts in Beringian Mammoth Tusks and a Bison Skull". United States. doi:. https://www.osti.gov/servlets/purl/1023384.
@article{osti_1023384,
title = {Micrometeorite Impacts in Beringian Mammoth Tusks and a Bison Skull},
author = {Hagstrum, Jonathon T. and Firestone, Richard B and West, Allen and Stefanka, Zsolt and Revay, Zsolt},
abstractNote = {We have discovered what appear to be micrometeorites imbedded in seven late Pleistocene Alaskan mammoth tusks and a Siberian bison skull. The micrometeorites apparently shattered on impact leaving 2 to 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 confirm the high iron content and indicate compositions highly enriched in nickel and depleted in titanium, unlike any natural terrestrial sources. In addition, electron microprobe (EMP) analyses of a Fe-Ni sulfide grain (tusk 2) show it contains between 3 and 20 weight percent Ni. Prompt gamma-ray activation analysis (PGAA) of a particle extracted from the bison skull indicates ~;;0.4 mg of iron, in agreement with a micrometeorite ~;;1 mm in diameter. In addition, scanning electron microscope (SEM) images and XRF analyses of the skull show possible entry channels containing Fe-rich material. The majority of tusks (5/7) have a calibrated weighted mean 14C age of 32.9 +- 1.8 ka BP, which coincides with the onset of significant declines<36 ka ago in Beringian bison, horse, brown bear, and mammoth populations, as well as in mammoth genetic diversity. It appears likely that the impacts and population declines are related events, although their precise nature remains to be determined.},
doi = {},
journal = {Journal of Siberian Federal University. Engineering&Technologies},
number = 1,
volume = 3,
place = {United States},
year = {Wed Feb 03 00:00:00 EST 2010},
month = {Wed Feb 03 00:00:00 EST 2010}
}