Multiple cosmogenic nuclides document the stability of the East Antarctic Ice Sheet in northern Victoria Land since the Late Miocene (5-7 Ma)

The timing and amplitude of changes in the Antarctic ice level are relevant to understanding past climate fluctuations and ongoing changes in the global climate and sea levels. In this study, we present surface exposure ages based on in situ produced cosmogenic Be-10 and Ne-21 in the bedrock samples of glacially eroded relict surfaces from the Deep Freeze Range, northern Victoria Land. The proximity of this region to the East Antarctic Ice Sheet indicates that the area is sensitive to variations in inland ice volume, permitting the investigation of the behavioural relationship between the East Antarctic Ice Sheet and the alpine glacial system in northern Victoria Land. Dating erosional surfaces provides a precise chronology of northern Victoria Land paleoclimate evolution and allows us to correlate the East Antarctic Ice Sheet response to global climate events and local ice level variations. The Be-10 and Ne-21 concentrations from the highest peaks of the Deep Freeze Range strongly indicate that the relict landscape features were continuously exposed for 5-7 Ma. Denudation rates inferred from our data show that the erosion rate of the summits has been extremely low (similar to 5 cm/Ma) for at least 5-7 Ma. Along with evidence of persistent climate stability (cold and arid conditions) from other sectors of the Transantarctic Mountains. our results indicate that the transition from the wet-based to the cold-based glacial regime in northern Victoria Land occurred after the creation of the polar East Antarctic Ice Sheet in the Middle Miocene. (C) 2012 Elsevier Ltd. All rights reserved.