Rapid early Holocene sea-level rise in Prydz Bay, East Antarctica
Prydz Bay is one of the largest embayments on the East Antarctic coast and it is the discharge point for approximately 16 % of the East Antarctic Ice Sheet. Geological constraints on the regional ice sheet history include evidence of past relative sea-level change at three sites; the Vestfold Hills, Rauer Islands and Larsemann Hills. In this paper we compile updated regional relative sea-level data from these sites. We compare these with a suite of relative sea-level predictions derived from glacial isostatic adjustment models and discuss the significance of departures between the models and the field evidence. The compiled geological data extend the relative sea-level curve for this region to 11258 cal yr BP and include new constraints based on abandoned penguin colonies, new isolation basin data in the Vestfold Hills, validation of a submarine relative sea-level constraint in the Rauer Islands and recalibrated radiocarbon ages at all sites dating from 12728 cal yr BP. The field data show rapid increases in rates of relative sea level rise of 12-48 mm/yr between 10473 (or 9678) and 9411 cal yr BP in the Vestfold Hills and of 8.8 mm/yr between 8882 and 8563 cal yr BP in the Larsemann Hills. The relative sea-level high stands of ≥ 8.8 m from 9411 to after 7564 cal yr BP (Vestfold Hills) and ≥ 8 m at 8563 and 7066 cal yr BP (Larsemann Hills) are over-predicted by some of the glacial isostatic adjustment models considered here, suggesting that assumptions relating to the magnitude and timing of regional ice loss since the Last Glacial Maximum may need revising. In the Vestfold Hills and Rauer Islands the final deglacial sea-level rise was almost exactly cancelled out by local rebound between 9411-5967 cal yr BP and this was followed by a near exponential decay in relative sea-level. In the Larsemann Hills the sea-level data suggest that the rate of ice retreat in this region was not uniform throughout the Holocene. Swath bathymetric surveys of the benthic seafloor topography show the presence of multiple offshore basins. These are a priority for further study as those free of grounded ice should provide precise constraints on relative sea-level rise and ice sheet history during the most rapid phases of the last major deglaciation.
Authors: Hodgson, Dominic A. ORCID record for Dominic A. Hodgson, Whitehouse, Pippa L., De Cort, Gijs, Berg, Sonja, Verleyen, Elie, Tavernier, Ines, Roberts, Stephen J. ORCID record for Stephen J. Roberts, Vyverman, Wim, Sabbe, Koen, O'Brien, Philip