EGU21-13150
https://doi.org/10.5194/egusphere-egu21-13150
EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

A stratigraphy-based method for reconstructing ice core orientation

Julien Westhoff1, Nicolas Stoll2, Steven Franke2, Ilka Weikusat2,3, Paul Bons3, Johanna Kerch2, Daniela Jansen2, Sepp Kipfstuhl1,2, and Dorthe Dahl-Jensen1,4
Julien Westhoff et al.
  • 1University of Copenhagen, Niels Bohr Institute, Physics of Ice, Climate and Earth, Copenhagen, Denmark (julien.westhoff@nbi.ku.dk)
  • 2Alfred Wegener, Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
  • 3Department of Geosciences, Eberhard Karls University Tübingen, Tübingen, Germany
  • 4Centre for Earth Observation Science, University of Manitoba, Winnipeg, Canada

Ever since the first deep ice cores were drilled, it has been a challenge to determine their original, in-situ orientation. In general, the orientation of an ice core is lost as the drill is free to rotate during transport to the surface. For shallow ice cores, it is usually possible to match the adjacent core breaks, which preserves the orientation of the ice column. However, this method fails for deep ice cores, such as the EastGRIP ice core in Northeast Greenland. We provide a method to reconstruct ice core orientation using visual stratigraphy and borehole geometry. As the EastGRIP ice core is drilled through the Northeast Greenland Ice Stream, we use information about the directional structures to perform a full geographical re-orientation. We compared the core orientation with logging data from core break matching and the pattern of the stereographic projections of the crystals’c-axis orientations. Both comparisons agree very well with the proposed orientation method. The method works well for 441 out of 451 samples from a depth of 1375–2120 m in the EastGRIP ice core. It can also be applied to other ice cores, providing a better foundation for interpreting physical properties and understanding the flow of ice.

How to cite: Westhoff, J., Stoll, N., Franke, S., Weikusat, I., Bons, P., Kerch, J., Jansen, D., Kipfstuhl, S., and Dahl-Jensen, D.: A stratigraphy-based method for reconstructing ice core orientation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13150, https://doi.org/10.5194/egusphere-egu21-13150, 2021.

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