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Monday, September 28, 2009

H. Schaefer et al., J. Glaciology (2009): Ice stratigraphy at the Pakitsoq ice margin, West Greenland, derived from gas records

Journal of Glaciology (2009), Vol. 55, No. 191, pp. 411-421.

Ice stratigraphy at the Pakitsoq ice margin, West Greenland, derived from gas records

H. Schaefer, V. V. Petrenko, E. J. Brook, J. P. Severinghaus, N. Reeh, J. R. Melton, and L. Mitchell

Technical University of Denmark, National Space Institute, Denmark


Horizontal ice-core sites, where ancient ice is exposed at the glacier surface, offer unique opportunities for paleo-studies of trace components requiring large sample volumes. Following previous work at the Pakitsoq ice margin in West Greenland, we use a combination of geochemical parameters measured in the ice matrix (delta O-18(ice)) and air occlusions (delta O-18(atm), delta N-15 of N-2 and methane concentration) to date ice layers from specific climatic intervals. The data presented here expand our understanding of the stratigraphy and three-dimensional structure of ice layers outcropping at Pakitsoq. Sections containing ice from every distinct climatic interval during Termination I, including Last Glacial Maximum, Bolling/Allerod, Younger Dryas and the early Holocene, are identified. In the early Holocene, we find evidence for climatic fluctuations similar to signals found in deep ice cores from Greenland. A second glacial-interglacial transition exposed at the extreme margin of the ice is identified as another outcrop of Termination I (rather than the onset of the Eemian interglacial as postulated in earlier work). Consequently, the main structural feature at Pakitsoq is a large-scale anticline with accordion-type folding in both exposed sequences of the glacial-Holocene transition, leading to multiple layer duplications and age reversals.

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