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| Titel |
Annual layering in the NGRIP ice core during the Eemian |
| VerfasserIn |
A. Svensson, M. Bigler, E. Kettner, D. Dahl-Jensen, S. Johnsen, S. Kipfstuhl, M. Nielsen, J. P. Steffensen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 7, no. 4 ; Nr. 7, no. 4 (2011-12-16), S.1427-1437 |
| Datensatznummer |
250004697
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| Publikation (Nr.) |
 copernicus.org/cp-7-1427-2011.pdf |
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| Zusammenfassung |
| The Greenland NGRIP ice core continuously covers the period from present day
back to 123 ka before present, which includes several thousand years of ice
from the previous interglacial period, MIS 5e or the Eemian. In the glacial
part of the core, annual layers can be identified from impurity records and
visual stratigraphy, and stratigraphic layer counting has been performed
back to 60 ka. In the deepest part of the core, however, the ice is close to
the pressure melting point, the visual stratigraphy is dominated by crystal
boundaries, and annual layering is not visible to the naked eye. In this
study, we apply a newly developed setup for high-resolution ice core
impurity analysis to produce continuous records of dust, sodium and ammonium
concentrations as well as conductivity of melt water. We analyzed three 2.2 m sections of ice from the Eemian and the glacial inception. In all of the
analyzed ice, annual layers can clearly be recognized, most prominently in
the dust and conductivity profiles. Part of the samples is, however,
contaminated in dust, most likely from drill liquid. It is interesting that
the annual layering is preserved despite a very active crystal growth and
grain boundary migration in the deep and warm NGRIP ice. Based on annual
layer counting of the new records, we determine a mean annual layer
thickness close to 11 mm for all three sections, which, to first order,
confirms the modeled NGRIP time scale (ss09sea). The counting does, however,
suggest a longer duration of the climatically warmest part of the NGRIP
record (MIS5e) of up to 1 ka as compared to the model estimate. Our results
suggest that stratigraphic layer counting is possible basically throughout
the entire NGRIP ice core, provided sufficiently highly-resolved
profiles become available. |
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