Abstract
The Weddell Sea sector is one of the main formation sites for Antarctic Bottom Water and an outlet for about one fifth of Antarctica's continental ice volume. Over the last few decades, studies on glacial–geological records in this sector have provided conflicting reconstructions of changes in ice-sheet extent and ice-sheet thickness since the Last Glacial Maximum (LGM at ca 23–19 calibrated kiloyears before present, cal ka BP). Terrestrial geomorphological records and exposure ages obtained from rocks in the hinterland of the Weddell Sea, ice-sheet thickness constraints from ice cores and some radiocarbon dates on offshore sediments were interpreted to indicate no significant ice thickening and locally restricted grounding-line advance at the LGM. Other marine geological and geophysical studies concluded that subglacial bedforms mapped on the Weddell Sea continental shelf, subglacial deposits and sediments over-compacted by overriding ice recovered in cores, and the few available radiocarbon ages from marine sediments are consistent with major ice-sheet advance at the LGM. Reflecting the geological interpretations, different ice-sheet models have reconstructed conflicting LGM ice-sheet configurations for the Weddell Sea sector. Consequently, the estimated contributions of ice-sheet build-up in the Weddell Sea sector to the LGM sea-level low-stand of ∼130 m vary considerably.In this paper, we summarise and review the geological records of past ice-sheet margins and past ice-sheet elevations in the Weddell Sea sector. We compile marine and terrestrial chronological data constraining former ice-sheet size, thereby highlighting different levels of certainty, and present two alternative scenarios of the LGM ice-sheet configuration, including time-slice reconstructions for post-LGM grounding-line retreat. Moreover, we discuss consistencies and possible reasons for inconsistencies between the various reconstructions and propose objectives for future research. The aim of our study is to provide two alternative interpretations of glacial–geological datasets on Antarctic Ice-Sheet History for the Weddell Sea sector, which can be utilised to test and improve numerical ice-sheet models.
Highlights
The Weddell Sea region in the Atlantic sector of Antarctica (Fig. 1) plays a key role for the global thermohaline circulation by ventilating the abyssal World Ocean in the Southern HemisphereC.-D
Even though the data base of marine and terrestrial geological records from the Weddell Sea sector and its hinterland has significantly increased over the last few years, the LGM to Holocene glacial history of this sector is still poorly known when compared to other sectors of the Antarctic Ice Sheet
Subglacial bedforms recorded in high-resolution bathymetric maps and seismic profiles from the Weddell Sea continental shelf document that the grounding lines of the West Antarctic Ice Sheet (WAIS) and East Antarctic Ice Sheet (EAIS) had advanced across the shelf in the past, probably during the Late Pleistocene
Summary
The Weddell Sea region in the Atlantic sector of Antarctica (Fig. 1) plays a key role for the global thermohaline circulation by ventilating the abyssal World Ocean in the Southern HemisphereC.-D. Interaction between sea ice, ice shelves and seawater on the continental shelf of the Weddell Sea Embayment (WSE) produces dense cool precursor water masses for Antarctic Bottom Water (AABW) which fills the deep Southern Ocean and spreads equatorwards into the deep-sea basins of the Atlantic, Indian and Pacific oceans: in the Atlantic sector AABW sensu lato reaches as far as w5S latitude As in other sectors of Antarctica, dynamical changes in the ice drainage basins surrounding the WSE have the potential to make major contributions to future sea-level rise (IPCC, 2007). The southern part of the embayment is covered by the FilchnereRonne Ice Shelf, one of the two major ice shelves in Antarctica, which has been identified as potentially critical to future WAIS stability (Hellmer et al, 2012)
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