Late Miocene ice sheet elevation in the Grove Mountains, East Antarctica, inferred from cosmogenic 21Ne–10Be–26Al

The Grove Mountains, lying in the interior of East Antarctica, consist of 64 nunataks. Geomorphic characteristics of the nunataks suggest that past ice sheet elevations have overtopped the summits of the Grove Mountains. Cosmogenic 21Ne, 10Be and 26Al dating yields surface exposure ages of five bedrock samples taken from the crest of Mount Harding, a typical nunatak in the Grove Mountains. Using multi-nuclide fitting, we have calculated the time that the ice sheet retreated below the crest of Mount Harding; all data point to the late Miocene, ∼ 6.3 Ma ago. The results provide the first land-based evidence of the elevation of the East Antarctic Ice Sheet in the Grove Mountains in Late Miocene, which reached 2300 m, 200 m higher than the current ice sheet level. The higher than current ice sheet elevations during the late Miocene together with contemporaneously higher temperatures in the Southern Ocean suggest that moisture transport plays an important role in ice sheet expansion in the interior of East Antarctica.