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The Cryosphere An interactive open-access journal of the European Geosciences Union
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We collected radar data between EDC, an ice core spanning ~800 thousand years, and BELDC, the site chosen for a new oldest ice core at nearby Little Dome C. These data allow us to identify 50 % older internal horizons than previously traced in the area. We fit a model to the ages of those horizons at BELDC to determine the age of deep ice there. We find that there is likely to be 1.5 million year old ice ~240 m above the bed, with sufficient resolution to preserve desired climatic information.
Preprints
https://doi.org/10.5194/tc-2020-345
https://doi.org/10.5194/tc-2020-345

  07 Dec 2020

07 Dec 2020

Review status: this preprint is currently under review for the journal TC.

Brief Communication: New radar constraints support presence of ice older than 1.5 Ma at Little Dome C

David A. Lilien1,, Daniel Steinhage2,, Drew Taylor3, Frédéric Parrenin4, Catherine Ritz4, Robert Mulvaney5, Carlos Martín5, Jie-Bang Yan3, Charles O'Neill3, Massimo Frezzotti6, Heinrich Miller2, Prasad Gogineni3, Dorthe Dahl-Jensen1,7, and Olaf Eisen2,8 David A. Lilien et al.
  • 1Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
  • 2Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung, Bremerhaven, Germany
  • 3Remote Sensing Center, University of Alabama, Tuscaloosa, AL, USA
  • 4University Grenoble Alpes, CNRS, IRD, IGE, Grenoble, France
  • 5British Antarctic Survey, Natural Environment Research Council, Cambridge, UK
  • 6Department of Science, University Roma Tre, Rome, Italy
  • 7Centre for Earth Observation Science, University of Manitoba, Winnipeg, MB, Canada
  • 8Department of Geosciences, University of Bremen, Bremen, Germany
  • These authors contributed equally to this work.

Abstract. The area near Dome C, East Antarctica, is thought to be one of the most promising targets for recovering a continuous ice-core record spanning more than a million years. The European Beyond EPICA consortium has selected Little Dome C, an area ~35 km south-east of Concordia Station, to attempt to recover such a record. Here, we present the results of the final ice-penetrating radar survey used to refine the exact drill site. These data were acquired during the 2019–2020 Austral summer using a new, multi-channel high-resolution VHF radar operating in the frequency range of 170–230 MHz. This new instrument is able to detect reflections in the near-basal region, where previous surveys were unable to trace continuous horizons. The radar stratigraphy is used to transfer the timescale of the EPICA Dome C ice core (EDC) to the area of Little Dome C, using radar isochrones dating back past 600 ka. We use these data to derive the expected depth–age relationship through the ice column at the now-chosen drill site, termed BELDC. These new data indicate that the ice at BELDC is considerably older than that at EDC at the same depth, and that there is about 375 m of ice older than 600 ka at BELDC. Stratigraphy is well preserved to 2565 m, below which there is a basal unit with unknown properties. A simple ice flow model tuned to the isochrones suggests ages likely reach 1.5 Ma near 2525 m, ~40 m above the basal unit and ~240 m above the bed, with sufficient resolution (14±1 ka m−1) to resolve 41 ka glacial cycles.

David A. Lilien et al.

 
Status: open (until 01 Feb 2021)
Status: open (until 01 Feb 2021)
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David A. Lilien et al.

David A. Lilien et al.

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Short summary
We collected radar data between EDC, an ice core spanning ~800 thousand years, and BELDC, the site chosen for a new oldest ice core at nearby Little Dome C. These data allow us to identify 50 % older internal horizons than previously traced in the area. We fit a model to the ages of those horizons at BELDC to determine the age of deep ice there. We find that there is likely to be 1.5 million year old ice ~240 m above the bed, with sufficient resolution to preserve desired climatic information.
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