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Title: Evidence for an extraterrestrial impact 12,900 years ago thatcontributed to megafaunal extinctions and the Younger Dryas cooling

Abstract

A carbon-rich black layer, dating to ~;12.9 ka, has beenpreviously identified at ~;50 Clovis-age sites across North America andappears contemporaneous with the abrupt onset of Younger Dryas (YD)cooling. The in situ bones of extinct Pleistocene megafauna and Clovistool assemblages occur below this black layer but not within or above it.Causes for the extinctions, the YD cooling, and the termination of Clovisculture have long been controversial. In this paper, we provide evidencefor an extraterrestrial (ET) impact event at ?12.9 ka, which, wehypothesize, caused abrupt environmental changes that contributed to YDcooling, major ecological reorganization, broad-scale extinctions, andrapid human behavioral shifts at the end of the Clovis Period. Clovis-agesites in North American are overlain by a thin, discrete layer withvarying peak abundances of: (1) magnetic grains with iridium, (2)magnetic microspherules (3) charcoal, (4) soot, (5) carbon spherules, (6)glass-like carbon, and (7) fullerenes with ET helium, all of which areevidence for an ET impact and associated biomass burning at ~;12.9 ka.This layer also extends throughout at least fifteen Carolina Bays, whichare unique, elliptical wetlands, oriented to thenorthwest across theAtlantic Coastal Plain. We propose that one or more large, low-density ETobjects exploded over northern North America, partially destabilizing theLaurentide Ice Sheet and triggering YD cooling.more » The shock wave, thermalpulse, and event-related environmental effects (e.g., extensive biomassburning, food limitations) contributed to the end-Pleistocene megafaunalextinctions and adaptive shifts among PaleoAmericans in NorthAmerica.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »; ; ; ; ; ; « less
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director, Office of Science; National ScienceFoundation
OSTI Identifier:
928884
Report Number(s):
LBNL-63274
R&D Project: NISON; BnR: KB0301042; TRN: US0803275
DOE Contract Number:  
DE-AC02-05CH11231; NSF:9986999, OCD-0244201, ANDATM-0713769
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proceedings of the National Academy ofSciences; Journal Volume: 104; Journal Issue: 41; Related Information: Journal Publication Date: 08/09/2007
Country of Publication:
United States
Language:
English
Subject:
60; 54; 07; AGE ESTIMATION; BIOMASS; CARBON; CHARCOAL; ENVIRONMENTAL EFFECTS; FOOD; FULLERENES; HELIUM; IRIDIUM; SHOCK WAVES; SOOT; WETLANDS; Comet impact Younger Dryas megafaunal extinction

Citation Formats

Firestone, R.B., West, A., Kennett, J.P., Becker, L., Bunch,T.E., Revay, Z.S., Schultz, P.H., Belgya, T., Kennett, D.J., Erlandson,J.M., Dickenson, O.J., Goodyear, A.C., Harris, R.S., Howard, G.A., Kloosterman, J.B., Lechler, P., Mayewski, P.A., Montgomery, J., Porede,R., Darrah, T., Que Hee, S.S., Smith, A.R., Stich, A., Topping, W., Wittke, J.H., and Wolbach, W.S. Evidence for an extraterrestrial impact 12,900 years ago thatcontributed to megafaunal extinctions and the Younger Dryas cooling. United States: N. p., 2007. Web.
Firestone, R.B., West, A., Kennett, J.P., Becker, L., Bunch,T.E., Revay, Z.S., Schultz, P.H., Belgya, T., Kennett, D.J., Erlandson,J.M., Dickenson, O.J., Goodyear, A.C., Harris, R.S., Howard, G.A., Kloosterman, J.B., Lechler, P., Mayewski, P.A., Montgomery, J., Porede,R., Darrah, T., Que Hee, S.S., Smith, A.R., Stich, A., Topping, W., Wittke, J.H., & Wolbach, W.S. Evidence for an extraterrestrial impact 12,900 years ago thatcontributed to megafaunal extinctions and the Younger Dryas cooling. United States.
Firestone, R.B., West, A., Kennett, J.P., Becker, L., Bunch,T.E., Revay, Z.S., Schultz, P.H., Belgya, T., Kennett, D.J., Erlandson,J.M., Dickenson, O.J., Goodyear, A.C., Harris, R.S., Howard, G.A., Kloosterman, J.B., Lechler, P., Mayewski, P.A., Montgomery, J., Porede,R., Darrah, T., Que Hee, S.S., Smith, A.R., Stich, A., Topping, W., Wittke, J.H., and Wolbach, W.S. Mon . "Evidence for an extraterrestrial impact 12,900 years ago thatcontributed to megafaunal extinctions and the Younger Dryas cooling". United States.
@article{osti_928884,
title = {Evidence for an extraterrestrial impact 12,900 years ago thatcontributed to megafaunal extinctions and the Younger Dryas cooling},
author = {Firestone, R.B. and West, A. and Kennett, J.P. and Becker, L. and Bunch,T.E. and Revay, Z.S. and Schultz, P.H. and Belgya, T. and Kennett, D.J. and Erlandson,J.M. and Dickenson, O.J. and Goodyear, A.C. and Harris, R.S. and Howard, G.A. and Kloosterman, J.B. and Lechler, P. and Mayewski, P.A. and Montgomery, J. and Porede,R. and Darrah, T. and Que Hee, S.S. and Smith, A.R. and Stich, A. and Topping, W. and Wittke, J.H. and Wolbach, W.S.},
abstractNote = {A carbon-rich black layer, dating to ~;12.9 ka, has beenpreviously identified at ~;50 Clovis-age sites across North America andappears contemporaneous with the abrupt onset of Younger Dryas (YD)cooling. The in situ bones of extinct Pleistocene megafauna and Clovistool assemblages occur below this black layer but not within or above it.Causes for the extinctions, the YD cooling, and the termination of Clovisculture have long been controversial. In this paper, we provide evidencefor an extraterrestrial (ET) impact event at ?12.9 ka, which, wehypothesize, caused abrupt environmental changes that contributed to YDcooling, major ecological reorganization, broad-scale extinctions, andrapid human behavioral shifts at the end of the Clovis Period. Clovis-agesites in North American are overlain by a thin, discrete layer withvarying peak abundances of: (1) magnetic grains with iridium, (2)magnetic microspherules (3) charcoal, (4) soot, (5) carbon spherules, (6)glass-like carbon, and (7) fullerenes with ET helium, all of which areevidence for an ET impact and associated biomass burning at ~;12.9 ka.This layer also extends throughout at least fifteen Carolina Bays, whichare unique, elliptical wetlands, oriented to thenorthwest across theAtlantic Coastal Plain. We propose that one or more large, low-density ETobjects exploded over northern North America, partially destabilizing theLaurentide Ice Sheet and triggering YD cooling. The shock wave, thermalpulse, and event-related environmental effects (e.g., extensive biomassburning, food limitations) contributed to the end-Pleistocene megafaunalextinctions and adaptive shifts among PaleoAmericans in NorthAmerica.},
doi = {},
journal = {Proceedings of the National Academy ofSciences},
number = 41,
volume = 104,
place = {United States},
year = {Mon Aug 06 00:00:00 EDT 2007},
month = {Mon Aug 06 00:00:00 EDT 2007}
}