Nanodiamonds in the Younger Dryas Boundary Sediment Layer

@article{Kennett2009NanodiamondsIT,
  title={Nanodiamonds in the Younger Dryas Boundary Sediment Layer},
  author={D. Kennett and J. Kennett and A. West and C. Mercer and S. Hee and L. Bement and T. Bunch and M. Sellers and W. Wolbach},
  journal={Science},
  year={2009},
  volume={323},
  pages={94 - 94}
}
We report abundant nanodiamonds in sediments dating to 12.9 ± 0.1 thousand calendar years before the present at multiple locations across North America. Selected area electron diffraction patterns reveal two diamond allotropes in this boundary layer but not above or below that interval. Cubic diamonds form under high temperature-pressure regimes, and n-diamonds also require extraordinary conditions, well outside the range of Earth's typical surficial processes but common to cosmic impacts. N… Expand
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References

SHOWING 1-9 OF 9 REFERENCES
Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling
TLDR
It is proposed that one or more large, low-density ET objects exploded over northern North America, partially destabilizing the Laurentide Ice Sheet and triggering YD cooling, which contributed to end-Pleistocene megafaunal extinctions and adaptive shifts among PaleoAmericans in North America. Expand
Younger Dryas “black mats” and the Rancholabrean termination in North America
  • C. Haynes
  • Geology, Medicine
  • Proceedings of the National Academy of Sciences
  • 2008
Of the 97 geoarchaeological sites of this study that bridge the Pleistocene-Holocene transition (last deglaciation), approximately two thirds have a black organic-rich layer or “black mat” in theExpand
Diamonds from the iridium-rich K-T boundary layer at Arroyo el Mimbral, Tamaulipas, Mexico
Diamonds, up to 30 µm in size, were found in the iridium-rich layer from the K-T boundary site at Arroyo El Mimbral and the spherule bed from Arroyo El Penon, northeastern Mexico. Stepped heatingExpand
Multiple diamond components in Acfer 182
An attempt has been made to isolate the carriers of isotopically ‘heavy’ (15N-enriched) nitrogen in the unusual chondrite Acfer 182, by preparing an oxidised HF/HCl-resistant residue. Analysis of theExpand
The 1908 Tunguska explosion: atmospheric disruption of a stony asteroid
The explosion over Tunguska, Central Siberia, in 1908 released 10 to 20 megatons (high explosive equivalent) of energy at an altitude of about 10 km. This event represents a typical fate for stonyExpand
Synthesis and crystal structure of n-diamond
Abstract Allotropes of carbon based materials, such as graphite, fullerenes and nanotubes, and diamond are currently a focus of great interest. New diamond (n-diamond) has been proposed as a newExpand
HST and VLT Investigations of the Fragments of Comet C/1999 S4 (LINEAR)
TLDR
At least 16 fragments were detected in images of comet C/1999 S4 (LINEAR) taken on 5 August 2000 with the Hubble Space Telescope and on 6 August with the Very Large Telescope, which implies that the total mass in the observed fragments was about 2 × 109 kilograms. Expand
Atmospheric concentrations of radiocarbon are known to have varied unevenly across past millennia; accordingly, 10,900 radiocarbon years before present has been recalibrated and is equivalent to 12
    This research was funded by the NSF (grant ATM-0713769). We thank three anonymous reviewers and V. Haynes for assistance