Shock-synthesized hexagonal diamonds in Younger Dryas boundary sediments

Douglas J. Kennett, James P. Kennett, Allen West, G. James West, Ted E. Bunch, Brendan J. Culleton, Jon M. Erlandson, Shane S. Que Hee, John R. Johnson, Chris Mercer, Feng Shen, Marilee Sellers, Thomas W. Stafford Jr, Adrienne Stich, James C. Weaver, James H. Wittke, and Wendy S. Wolbach
PNAS August 4, 2009 106 (31) 12623-12628; https://doi.org/10.1073/pnas.0906374106

  1. Communicated by Steven M. Stanley, University of Hawaii, Honolulu, HI, June 11, 2009 (received for review March 3, 2009)

Abstract

The long-standing controversy regarding the late Pleistocene megafaunal extinctions in North America has been invigorated by a hypothesis implicating a cosmic impact at the Ållerød-Younger Dryas boundary or YDB (≈12,900 ± 100 cal BP or 10,900 ± 100 14C years). Abrupt ecosystem disruption caused by this event may have triggered the megafaunal extinctions, along with reductions in other animal populations, including humans. The hypothesis remains controversial due to absence of shocked minerals, tektites, and impact craters. Here, we report the presence of shock-synthesized hexagonal nanodiamonds (lonsdaleite) in YDB sediments dating to ≈12,950 ± 50 cal BP at Arlington Canyon, Santa Rosa Island, California. Lonsdaleite is known on Earth only in meteorites and impact craters, and its presence strongly supports a cosmic impact event, further strengthened by its co-occurrence with other nanometer-sized diamond polymorphs (n-diamonds and cubics). These shock-synthesized diamonds are also associated with proxies indicating major biomass burning (charcoal, carbon spherules, and soot). This biomass burning at the Younger Dryas (YD) onset is regional in extent, based on evidence from adjacent Santa Barbara Basin and coeval with broader continent-wide biomass burning. Biomass burning also coincides with abrupt sediment mass wasting and ecological disruption and the last known occurrence of pygmy mammoths (Mammuthus exilis) on the Channel Islands, correlating with broader animal extinctions throughout North America. The only previously known co-occurrence of nanodiamonds, soot, and extinction is the Cretaceous-Tertiary (K/T) impact layer. These data are consistent with abrupt ecosystem change and megafaunal extinction possibly triggered by a cosmic impact over North America at ≈12,900 ± 100 cal BP.

Footnotes

  • 1To whom correspondence should be addressed. E-mail: dkennett{at}uoregon.edu

  • Author contributions: D.J.K., J.P.K., T.E.B., J.M.E., S.S.Q.H., F.S., and W.S.W. designed research; D.J.K., J.P.K., A.W., G.J.W., T.E.B., B.J.C., J.M.E., J.R.J., C.M., F.S., M.S., A.S., J.C.W., J.H.W., and W.S.W. performed research; S.S.Q.H. and W.S.W. contributed new reagents/analytic tools; D.J.K., J.P.K., A.W., G.J.W., T.E.B., J.M.E., C.M., F.S., T.W.S., J.C.W., J.H.W., and W.S.W. analyzed data; and D.J.K. and J.P.K. wrote the paper.

  • The authors declare no conflict of interest.

  • ↵* Ages in this paper are expressed in thousands of calendar years before present (ka). Radiocarbon ages will be identified and clearly marked “14C years.”

  • This article contains supporting information online at www.pnas.org/cgi/content/full/0906374106/DCSupplemental.

  1. Douglas J. Kennetta,1,
  2. James P. Kennettb,
  3. Allen Westc,
  4. G. James Westd,
  5. Ted E. Bunche,
  6. Brendan J. Culletona,
  7. Jon M. Erlandsona,f,
  8. Shane S. Que Heeg,
  9. John R. Johnsonh,
  10. Chris Merceri,j,
  11. Feng Shenk,
  12. Marilee Sellerse,
  13. Thomas W. Stafford, Jrl,
  14. Adrienne Stichm,
  15. James C. Weavern,
  16. James H. Wittkee and
  17. Wendy S. Wolbachm
  1. aDepartment of Anthropology and
  2. fMuseum of Natural and Cultural History, University of Oregon, Eugene, OR 97403;
  3. bDepartment of Earth Science and Marine Science Institute and
  4. jMaterials Department, University of California, Santa Barbara, CA 93106;
  5. cGeoScience Consulting, Dewey, AZ 86327;
  6. dDepartment of Anthropology, University of California, Davis, CA 95616;
  7. eDepartment of Geology and Imaging and Histology Core Facility, Northern Arizona University, Flagstaff, AZ 86011;
  8. gDepartment of Environmental Health Sciences, University of California, Los Angeles, CA 90095-1772;
  9. hSanta Barbara Museum of Natural History, 2559 Puesta del Sol, Santa Barbara, CA 93105;
  10. iNational Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan;
  11. kFEI Company, 5350 Northeast Dawson Creek Drive, Hillsboro, OR 97124;
  12. lStafford Research, Inc., 200 Acadia Avenue, Lafayette, CO 80026;
  13. mDepartment of Chemistry, DePaul University, Chicago, IL 60604; and
  14. nDepartment of Chemical and Environmental Engineering, University of California, Riverside, CA 92521

  1. Communicated by Steven M. Stanley, University of Hawaii, Honolulu, HI, June 11, 2009 (received for review March 3, 2009)

Abstract

The long-standing controversy regarding the late Pleistocene megafaunal extinctions in North America has been invigorated by a hypothesis implicating a cosmic impact at the Ållerød-Younger Dryas boundary or YDB (≈12,900 ± 100 cal BP or 10,900 ± 100 14C years). Abrupt ecosystem disruption caused by this event may have triggered the megafaunal extinctions, along with reductions in other animal populations, including humans. The hypothesis remains controversial due to absence of shocked minerals, tektites, and impact craters. Here, we report the presence of shock-synthesized hexagonal nanodiamonds (lonsdaleite) in YDB sediments dating to ≈12,950 ± 50 cal BP at Arlington Canyon, Santa Rosa Island, California. Lonsdaleite is known on Earth only in meteorites and impact craters, and its presence strongly supports a cosmic impact event, further strengthened by its co-occurrence with other nanometer-sized diamond polymorphs (n-diamonds and cubics). These shock-synthesized diamonds are also associated with proxies indicating major biomass burning (charcoal, carbon spherules, and soot). This biomass burning at the Younger Dryas (YD) onset is regional in extent, based on evidence from adjacent Santa Barbara Basin and coeval with broader continent-wide biomass burning. Biomass burning also coincides with abrupt sediment mass wasting and ecological disruption and the last known occurrence of pygmy mammoths (Mammuthus exilis) on the Channel Islands, correlating with broader animal extinctions throughout North America. The only previously known co-occurrence of nanodiamonds, soot, and extinction is the Cretaceous-Tertiary (K/T) impact layer. These data are consistent with abrupt ecosystem change and megafaunal extinction possibly triggered by a cosmic impact over North America at ≈12,900 ± 100 cal BP.

  • Arlington Canyon
  • biomass burning
  • cosmic impact
  • hexagonal nanodiamonds
  • megafaunal extinctions

Footnotes

  • 1To whom correspondence should be addressed. E-mail: dkennett{at}uoregon.edu

  • Author contributions: D.J.K., J.P.K., T.E.B., J.M.E., S.S.Q.H., F.S., and W.S.W. designed research; D.J.K., J.P.K., A.W., G.J.W., T.E.B., B.J.C., J.M.E., J.R.J., C.M., F.S., M.S., A.S., J.C.W., J.H.W., and W.S.W. performed research; S.S.Q.H. and W.S.W. contributed new reagents/analytic tools; D.J.K., J.P.K., A.W., G.J.W., T.E.B., J.M.E., C.M., F.S., T.W.S., J.C.W., J.H.W., and W.S.W. analyzed data; and D.J.K. and J.P.K. wrote the paper.

  • The authors declare no conflict of interest.

  • ↵* Ages in this paper are expressed in thousands of calendar years before present (ka). Radiocarbon ages will be identified and clearly marked “14C years.”

  • This article contains supporting information online at www.pnas.org/cgi/content/full/0906374106/DCSupplemental.

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Shock-synthesized hexagonal diamonds in Younger Dryas boundary sediments
Douglas J. Kennett, James P. Kennett, Allen West, G. James West, Ted E. Bunch, Brendan J. Culleton, Jon M. Erlandson, Shane S. Que Hee, John R. Johnson, Chris Mercer, Feng Shen, Marilee Sellers, Thomas W. Stafford, Adrienne Stich, James C. Weaver, James H. Wittke, Wendy S. Wolbach
Proceedings of the National Academy of Sciences Aug 2009, 106 (31) 12623-12628; DOI: 10.1073/pnas.0906374106
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