EGU2020-19999
https://doi.org/10.5194/egusphere-egu2020-19999
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

A 14.5 million-year geologic record of East Antarctic Ice Sheet fluctuations in the central Transantarctic Mountains, constrained with multiple cosmogenic nuclides

Gordon Bromley1, Alexandra Balter2, Greg Balco3, and Margaret Jackson1
Gordon Bromley et al.
  • 1Department of Geography, Archaeology, and Irish Studies, National University of Ireland Galway, Galway, Ireland
  • 2Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, United States
  • 3Berkeley Geochronology Center, Berkeley, California, United States

The distribution of relict moraines in the Transantarctic Mountains affords geologic constraint of past ice-marginal positions of the East Antarctic Ice Sheet (EAIS). We describe the directly dated glacial-geologic record from Roberts Massif, an ice-free area in the central Transantarctic Mountains, to provide a comprehensive record of ice sheet change at this site since the Miocene and to capture ice sheet response to warmer-than-present climate conditions. The record is constrained by cosmogenic 3He, 10Be, 21Ne, and 26Al surface-exposure ages from > 160 dolerite and sandstone erratics on well-preserved moraines and drift units. Our data set indicates that a cold-based EAIS was present, and similar to its current configuration, for long periods over the last ~14.5 Myr, including the mid-Miocene, Late Pliocene, and early-to-mid Pleistocene, with moraine ages increasing with distance from and elevation above the modern ice margin. We also report extremely low erosion rates over the duration of our record, reflecting long-term polar desert conditions at Roberts Massif. The age-elevation distribution of moraines at Roberts Massif is consistent with a persistent EAIS extent during glacial maxima, accompanied by slow, isostatic uplift of the massif due to subglacial erosion. Although our data are not a direct measure of ice volume, the Roberts Massif glacial record indicates that the EAIS was present and of similar extent to today during periods when global temperature was believed to be warmer and/or atmospheric CO2 concentrations were likely higher than today.

How to cite: Bromley, G., Balter, A., Balco, G., and Jackson, M.: A 14.5 million-year geologic record of East Antarctic Ice Sheet fluctuations in the central Transantarctic Mountains, constrained with multiple cosmogenic nuclides, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19999, https://doi.org/10.5194/egusphere-egu2020-19999, 2020

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