A topographic hinge-zone divides coastal and inland ice dynamic regimes in East Antarctica

Abstract

The impact of late Cenozoic climate on the East Antarctic Ice Sheet is uncertain. Poorly constrained patterns of relative ice thinning and thickening impair the reconstruction of past ice-sheet dynamics and global sea-level budgets. Here we quantify long-term ice cover of mountains protruding the ice-sheet surface in western Dronning Maud Land, using cosmogenic Chlorine-36, Aluminium-26, Beryllium-10, and Neon-21 from bedrock in an inverse modeling approach. We find that near-coastal sites experienced ice burial up to 75–97% of time since 1 Ma, while interior sites only experienced brief periods of ice burial, generally <20% of time since 1 Ma. Based on these results, we suggest that the escarpment in Dronning Maud Land acts as a hinge-zone, where ice-dynamic changes driven by grounding-line migration are attenuated inland from the coastal portions of the East Antarctic Ice Sheet, and where precipitation-controlled ice-thickness variations on the polar plateau taper off towards the coast.

Spatiotemporal variations in the East Antarctic Ice Sheet during the Holocene

“…By dating the rocks that have been exposed due to ice retreat, we can determine the timing of the ice retreat. The cosmogenic nuclide dating of erratic and bedrock collected at various altitudes has been utilized to reconstruct the changes in heights of the EAIS since the Last Glacial Maximum (Andersen et al, 2023;Balco et al, 2023;Kawamata et al, 2020;Suganuma et al, 2014;Johnson et al, 2020;Suganuma et al, 2022;White et al, 2011;White and Fink, 2014;Yamane et al, 2011). Recent studies in Dronning Maud Land revealed early to mid Holocene ice-sheet thinning, indicating a discrepancy (delay) in the timing of deglaciation in previous studies that employed the ICE-6G model (Argus et al, 2014;Peltier et al, 2018).…”