Abstract
Contemporary climate change has resulted in great uncertainty in how glaciers and ice sheets around the Earth might evolve. It has long been appreciated that the contemporary West Antarctic Ice Sheet (WAIS) shares many similarities with the former Barents Sea Ice Sheet (BSIS). Therefore, an increasing number of studies have sought to investigate the Barents Sea glacial record to better understand marine-based glaciation. This paper reports the analysis of a new high-resolution bathymetric survey covering ~55,000km2 in the central Barents Sea. The relative chronologies of newly-mapped glacial landforms such as mega-scale glacial lineations, grounding-zone wedges, moraines, and crevasse-squeeze ridges are used to reconstruct the ice sheet dynamics in the central Barents Sea. Our results show that the ice sheet responded dynamically with different periods of retreat, advance, and stagnation observed. These new landform records have been integrated with other geomorphological records in order to reconstruct the retreat pattern of the BSIS between 17–14ka, when the Fennoscandian Ice Sheet is thought to have uncoupled from the BSIS. Our data shows that the dynamic drawdown of the ice sheet saddle by ice streams was probably the primary mechanism in separating the two ice sheets. After the ice sheets uncoupled, the BSIS is shown to have retreated episodically with several periods of relative stability. Geomorphological records such as those from the BSIS can be used to constrain ice sheet modelling and will help to develop a clearer understanding of marine-based glaciation and the role of ice streams in driving ice sheet evolution.
Highlights
Sedimentary records on high-latitude margins are important for reconstructing palaeo-ice sheets and their dynamics (Solheim et al, 1990; Jansen and Sjøholm, 1991; Vorren and Laberg, 1997; Ottesen et al, 2005). Mercer (1970) first suggested that an ice sheet similar in size to the West Antarctic Ice Sheet (WAIS) may have existed over the Barents Sea shelf at the Last Glacial Maximum (LGM)
These new landform records have been integrated with other geomorphological records in order to reconstruct the retreat pattern of the Barents Sea Ice Sheet (BSIS) between 17–14 ka, when the Fennoscandian Ice Sheet is thought to have uncoupled from the BSIS
Observations from new bathymetric data in the central Barents Sea have been integrated with those already published to establish the late Weichselian ice sheet history of the central Barents Sea between 17–14 ka. During this period the BSIS and Fennoscandian Ice Sheet (FIS) are thought to have separated (Hughes et al, 2016; Stroeven et al, 2016) and the geomorphological record presented here suggests that the two ice sheets uncoupled in the southern Barents Sea, close to the Djuprenna and Kola troughs
Summary
Sedimentary records on high-latitude margins are important for reconstructing palaeo-ice sheets and their dynamics (Solheim et al, 1990; Jansen and Sjøholm, 1991; Vorren and Laberg, 1997; Ottesen et al, 2005). Mercer (1970) first suggested that an ice sheet similar in size to the West Antarctic Ice Sheet (WAIS) may have existed over the Barents Sea shelf at the Last Glacial Maximum (LGM). An initial perturbation of the grounding-line location (the area where ice becomes sufficiently buoyant to float) can lead to increased ice sheet discharge (Weertman, 1974; Hughes, 1981; Schoof, 2007) until a new steady-state is reached (Joughin and Alley, 2011; Jakobsson et al, 2012a; Jamieson et al, 2012) This scenario is concerning because of the potential sea level contribution of the WAIS (Rohling et al, 2009) and ongoing observations of grounding-line retreat and ice stream thinning and velocity increase (Pritchard et al, 2009; Wingham et al, 2009; Rignot et al, 2011). The geological setting of the WAIS is different to that of the BSIS, understanding the retreat of different marine-based ice sheets will allow for a more complete model of marine-based glaciation to be developed (Denton et al, 2010; Ingólfsson and Landvik, 2013)
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