Preprints
https://doi.org/10.5194/esurf-2020-50
https://doi.org/10.5194/esurf-2020-50

  08 Jul 2020

08 Jul 2020

Review status: a revised version of this preprint is currently under review for the journal ESurf.

Relative terrestrial exposure ages inferred from meteoric 10Be and NO3 concentrations in soils along the Shackleton Glacier, Antarctica

Melisa A. Diaz1,2, Lee B. Corbett3, Paul R. Bierman3, Byron J. Adams4, Diana H. Wall5, Ian D. Hogg6,7, Noah Fierer8, and W. Berry Lyons1,2 Melisa A. Diaz et al.
  • 1School of Earth Sciences, The Ohio State University, Columbus, OH, 43210, USA
  • 2Byrd Polar and Climate Research Center, The Ohio State University, Columbus, OH, 43210, USA
  • 3Department of Geology, University of Vermont, Burlington, VT, 05405, USA
  • 4Department of Biology, Evolutionary Ecology Laboratories, and Monte L. Bean Museum, Brigham Young University, Provo, UT, 84602, USA
  • 5Department of Biology and School of Global Environmental Sustainability, Colorado State University, Fort Collins, CO, 80523, USA
  • 6Canadian High Arctic Research Station, Polar Knowledge Canada, Cambridge Bay, NU,X0B0C0, Canada
  • 7School of Science, University of Waikato, Hamilton, 3216, New Zealand
  • 8Department of Ecology and Evolutionary Biology and Cooperative Institute for Research in Environmental Science, University of Colorado Boulder, Boulder, CO, 80309, USA

Abstract. Modeling studies and field mapping show that increases in ice thickness during glacial periods were not uniform across Antarctica. Rather, outlet glaciers that flow through the Transantarctic Mountains (TAM) experienced the greatest changes in ice thickness. As a result, ice-free areas that are currently exposed may have been covered by ice at various points during the Cenozoic, thereby providing a record of past ice sheet behavior. We collected soil surface samples and depth profiles every 5 cm to refusal (up to 30 cm) from eleven ice-free areas along the Shackleton Glacier, a major outlet glacier of the East Antarctic Ice Sheet (EAIS) and measured meteoric 10Be and NO3 concentrations to calculate and estimate surface exposure ages. Using 10Be inventories from three locations, calculated maximum exposure ages range from 4.1 Myr at Roberts Massif near the Polar Plateau to 0.11 Myr at Bennett Platform further north. When corrected for inheritance of 10Be from prior exposure, the ages (representing a minimum) range from 0.14 Myr at Roberts Massif to 0.04 Myr at Thanksgiving Valley. We correlate NO3 concentrations with meteoric 10Be to estimate exposure ages for all locations with NO3 depth profiles but only surface 10Be data. These results indicate that NO3 concentrations can be used in conjunction with meteoric 10Be to help interpret EAIS dynamics over time. We show that the Shackleton Glacier has the greatest fluctuations near the Ross Ice Shelf while tributary glaciers are more stable, reflecting the sensitivity of the EAIS to climate shifts at TAM margins.

Melisa A. Diaz et al.

 
Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

Melisa A. Diaz et al.

Melisa A. Diaz et al.

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Short summary
We collected soil surface samples and depth profiles every 5 cm (up to 30 cm) from eleven ice-free areas along the Shackleton Glacier, a major outlet glacier of the East Antarctic Ice Sheet (EAIS) and measured meteoric beryllium-10 and nitrate concentrations to calculate and estimate surface exposure ages. We show that the Shackleton Glacier has the greatest fluctuations near the terminus while tributary glaciers are more stable, reflecting the sensitivity of the EAIS to climate shifts.