Retreat patterns and dynamics of the Sentralbankrenna glacial system, central Barents Sea

Abstract

10The Barents Sea Ice Sheet (BSIS) is a good palaeo-analogue for the present day West Antarctic 11 Ice Sheet. Both were marine-based ice sheets, particularly vulnerable to ocean warming and 12 sea-level rise. Understanding the BSIS ice dynamics and patterns of retreat since the Last 13 Glacial Maximum (LGM) is useful in developing our knowledge of spatial and temporal 14 variations during marine-based ice sheet retreat. While the western margins of the Barents Sea 15 have been extensively studied, few studies have focused on the central regions, which hosted 16 key ice stream tributaries and major ice domes and divides. Presenting a new high-resolution 17 (5 m) bathymetric dataset, this glacial geomorphological study focuses on the Sentralbankrenna 18 palaeo-glacial system in the central Barents Sea. A large number of grounding zone wedges, 19 mega-scale glacial lineations and areas with tunnel valleys and palaeo-subglacial basins were 20 identified. These form the basis for a six-stage reconstruction of ice stream retreat through 21 deglaciation since the LGM. In reconstructing the retreat of the Sentralbankrenna Ice Stream, 22 we document the rapid but highly spatially variable pattern of retreat of a marine-based ice 23 sheet margin. The presence of several tunnel valleys and interconnected palaeo-subglacial basin 24 systems indicates an abundance of meltwater, likely to have been stored and released through 25 several discharge events, significantly influencing the ice stream margin dynamics. This study 26 provides insight into the behaviour and dynamics of ice during the late stages of the BSIS 27 deglaciation within the central Barents Sea, increasing our understanding of grounding line 28 processes. 29 30 31 2

Subglacial water storage and drainage beneath the Fennoscandian and Barents Sea ice sheets

“…7b). It is suggested that the subglacial hydrology of this region was characterised by fill/drain cycles and periodic outburst flooding from hypothesised subglacial lakes (Bjarnadóttir et al, 2016;Esteves et al, 2017;In Review), compatible with the clusters of lakes predicted in this study. The lower number of times subglacial lakes are predicted at sites in the central Barents Sea compared to those in the Gulf of Bothnia (Fig.…”

“…4b) suggests that surface meltwater penetrating to the bed could have been stored in subglacial lakes and released on varying timescales, further modulating the stability and dynamic activity of the ice stream. Similarly, given the evidence for high-discharge subglacial meltwater systems in the central Barents Sea (Bjarnadóttir et al, 2017;Esteves et al, 2017), it it likely that ice flow of the Sentralbankrenna Ice Stream, and the neighbouring Bjørnøyrenna Ice Stream (Fig. 1), would have been regulated by the filling and draining of the subglacial lakes predicted in their onset zones (Fig.…”

“…Evidence for highly dynamic ice stream activity is recorded in the geomorphology of their former beds, with cross-cutting sets of mega-scale glacial lineations indicating numerous switches in flow direction during the LGM (Piasecka et al, 2016). Furthermore, grounding zone wedges containing evidence for ice-marginal subglacial meltwater dicharge suggest cycles of ice margin retreat, stability, and re-advance influenced by sustained basal hydrological activity during overall retreat (Bjarnadóttir et al, 2014;Esteves et al, 2017;Newton and Huuse, 2017).…”

Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, north-west Greenland

“…Ottesen and Dowdeswell, 2006;Flink et al, 2015) or GZWs (e.g. Bjarnardóttir et al, 2013;Esteves et al, 2017). Here, they may reflect local shifts in the location of the grounding zone during a phase of ice shelf instability interpreted from core records prior to further grounding-zone retreat.…”

A conceptual model for glaciogenic reservoirs: From landsystems to reservoir architecture

“…Dowdeswell et al, 2008;Ó Cofaigh et al, 2003), where the bathymetry and sedimentology of continental shelves, all the way out to the shelf break, reveals a rich assemblage of glacial landforms and sediments associated with proximal grounded ice (e.g. Andreassen and Winsborrow, 2009; L. R. Bjarnadóttir and Andreassen, 2016;Dowdeswell and Fugelli, 2012;Esteves et al, 2017;Greenwood et al, 2018;Hodgson et al, 2014;King et al, 2016;Kurjanski et al, 2019) (Bjarnadóttir and Andreassen, 2016;Greenwood et al, 2018;Hodgson et al, 2014;King et al, 2016;Kurjanski et al, 2019). However, large volumes of sediments delivered subglacially to the shelf break and deposited on the continental slope during glaciation can cause the shelf to prograde basinward (Figure 6) (Eyles et al, 1985;Knutz et al, 2019;Ottesen et al, 2012).…”