New constraints on the timing of West Antarctic Ice Sheet retreat in the eastern Amundsen Sea since the Last Glacial Maximum

Smith, James A; Hillenbrand, Claus‐Dieter; Kuhn, Gerhard; Klages, Johann Philipp; Graham, Alastair G C; Larter, Robert D; Ehrmann, Werner; Moreton, Steven G.; Wiers, Steffen; Frederichs, Thomas

doi:10.1016/j.gloplacha.2014.07.015

Cited by 76 publications

(81 citation statements)

References 73 publications

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“…If these landforms are coeval, as we suggest, then they indicate a uniform pattern of episodic grounding-line retreat across the eastern ASE following the LGM (e.g., Smith et al, 2014). …”

Section: Discussionmentioning

confidence: 70%

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Palaeo-ice stream pathways and retreat style in the easternmost Amundsen Sea Embayment, West Antarctica, revealed by combined multibeam bathymetric and seismic data

et al. 2015

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Multibeam swath bathymetry data sets collected over the past two decades have been compiled to identify palaeo-ice stream pathways in the easternmost Amundsen Sea Embayment. We mapped~3000 glacial landforms to reconstruct ice flow in the~250-km-long cross-shelf Abbot Trough. This bathymetric feature was occupied by a large ice stream, which was fed by two tributaries (Cosgrove and Abbot) and reached the continental shelf edge during the last maximum ice sheet advance. Geomorphological mapping has enabled a clear differentiation between subglacial landforms indicating warm-(e.g., megascale glacial lineations) and cold-based (e.g., hill-hole pairs) ice conditions on the continental shelf during the last glaciation. Grounding-zone wedges and recessional moraines, mapped within the palaeo-ice stream troughs and on adjacent sea-floor highs (referred to as inter-ice stream ridges) indicate grounding line stillstands or re-advances of the West Antarctic Ice Sheet during the last deglaciation of the shelf. We observe that the locations of grounding-zone wedges coincide with trough constrictions as well as local topographic highs of harder substrate. This combination of trough 'bottlenecks' and local pinning points on an otherwise retrograde slope is likely to have modified the pace of grounding-line retreat, causing the grounding zone to pause and deposit grounding-zone wedges. The episodic retreat recorded within Abbot Trough corresponds to post-glacial episodic retreat interpreted for the neighbouring Pine Island-Thwaites palaeo-ice stream trough, thus suggesting a uniform pattern of retreat across the eastern Amundsen Sea Embayment. Locally, indications are strong that a change in basal thermal regime of the ice from warm-to cold-based conditions occurred prior to final retreat, as hill-hole pairs overprint megascale glacial lineations. Further, the correlation of grounding-zone wedges with geological boundaries emphasises the influence of subglacial geology on ice stream flow. Our new geomorphological map of the easternmost Amundsen Sea Embayment resolves the pathways of palaeo-ice streams that were probably all active during the last maximum extent of the ice sheet, and the extent of adjacent inter-ice stream ridges. It reveals information about the style of, and the basal thermal regime during, the subsequent grounding line retreat. Such information provides an important empirical framework by which the accuracy of ice sheet models can be gauged.

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“…If these landforms are coeval, as we suggest, then they indicate a uniform pattern of episodic grounding-line retreat across the eastern ASE following the LGM (e.g., Smith et al, 2014). …”

Section: Discussionmentioning

confidence: 70%

“…A coherent grounding line retreat is also indicated by several sets of recessional moraines on the inter-stream ridge between PIT and AT that record a stepwise retreat (Figs. 2, 3), which might also correlate with the formation of GZWc and GZW5 in the neighbouring troughs (e.g., Smith et al, 2014).…”

Section: Relationships To Main Palaeo-ice Stream Flow In Pitmentioning

confidence: 96%

Palaeo-ice stream pathways and retreat style in the easternmost Amundsen Sea Embayment, West Antarctica, revealed by combined multibeam bathymetric and seismic data

et al. 2015

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“…Drumlinoid features (indicated by black arrows) of unknown age are observed in the centre of the basin documenting that grounded ice was present there18, probably during the LGM like in the wider region202122 (Fig. 1a,b).…”

Section: Figurementioning

confidence: 96%

Evidence for a palaeo-subglacial lake on the Antarctic continental shelf

et al. 2017

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Subglacial lakes are widespread beneath the Antarctic Ice Sheet but their control on ice-sheet dynamics and their ability to harbour life remain poorly characterized. Here we present evidence for a palaeo-subglacial lake on the Antarctic continental shelf. A distinct sediment facies recovered from a bedrock basin in Pine Island Bay indicates deposition within a low-energy lake environment. Diffusive-advection modelling demonstrates that low chloride concentrations in the pore water of the corresponding sediments can only be explained by initial deposition of this facies in a freshwater setting. These observations indicate that an active subglacial meltwater network, similar to that observed beneath the extant ice sheet, was also active during the last glacial period. It also provides a new framework for refining the exploration of these unique environments.

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“…A broadly similar picture has emerged for the other glaciers that drain into the eastern Amundsen Sea (Thwaites, Haynes, Smith, Pope, and Kohler Glaciers), with all showing periods of rapid grounding-line retreat and Figure 5 (key to right with year and number of stations), and the circled black cross shows the location of mooring records also used in Figure 5. Names of seabed troughs, including Pine Island-Thwaites East (PITE) and Pine Island-Thwaites West (PITW) follow Smith et al (2014), while bathymetry comes from the RTopo-1 gridded data set (Timmermann et al, 2010).…”

Section: Glaciological Change In the Amundsen Sea Sectormentioning

confidence: 99%

Decadal Ocean Forcing and Antarctic Ice Sheet Response: Lessons from the Amundsen Sea

et al. 2016

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New constraints on the timing of West Antarctic Ice Sheet retreat in the eastern Amundsen Sea since the Last Glacial Maximum

Cited by 76 publications

References 73 publications

Palaeo-ice stream pathways and retreat style in the easternmost Amundsen Sea Embayment, West Antarctica, revealed by combined multibeam bathymetric and seismic data

Palaeo-ice stream pathways and retreat style in the easternmost Amundsen Sea Embayment, West Antarctica, revealed by combined multibeam bathymetric and seismic data

Evidence for a palaeo-subglacial lake on the Antarctic continental shelf

Decadal Ocean Forcing and Antarctic Ice Sheet Response: Lessons from the Amundsen Sea

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