Murray Springs Clovis site, Pleistocene extinction, and the question of extraterrestrial impact

Some of the evidence for the recent hypothesis of an extraterrestrial impact that caused late Pleistocene megafaunal extinctions [Firestone et al. (2007) Proc Natl Acad Sci USA 104:16016-16021] was based upon samples collected at Murray Springs, a Clovis archaeological site in southeastern Arizona....

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2010-03, Vol.107 (9), p.4010-4015
Main Authors: Haynes, C. Vance Jr, Boerner, J, Domanik, K, Lauretta, D, Ballenger, J, Goreva, J
Format: Article
Language:English
Subjects:
Archaeology
Biomass
Biomass burning
Charcoal
Cosmic dust
Extinction
Extinction, Biological
Fossils
Magnetics
Magnetism
Magnetite
Mass Spectrometry
New Mexico
Physical Sciences
Planetary science
Prehistoric era
Radiation
Radiocarbon
Sand
Sediments
Silts
Younger Dryas period
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Summary:Some of the evidence for the recent hypothesis of an extraterrestrial impact that caused late Pleistocene megafaunal extinctions [Firestone et al. (2007) Proc Natl Acad Sci USA 104:16016-16021] was based upon samples collected at Murray Springs, a Clovis archaeological site in southeastern Arizona. Here we describe sampling and analyses of magnetic separates from within, above, and below the lower Younger Dryas boundary (LYDB) black mat at Murray Springs, as well as radiation measurements from the LYDB at Murray Springs and two other well-stratified Clovis sites. The main magnetic fraction at Murray Springs is maghemite. Magnetic microspherules have terrestrial origins but also occur as cosmic dust particles. We failed to find iridium or radiation anomalies. The evidence for massive biomass burning at Murray Springs is addressed and found to be lacking. We could not substantiate some of the claims by Firestone and others, but our findings do not preclude a terminal Pleistocene cosmic event.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0908191107