Geophysical constraints on the dynamics and retreat of the Barents Sea ice sheet as a paleobenchmark for models of marine ice sheet deglaciation

Abstract

Our understanding of processes relating to the retreat of marine‐based ice sheets, such as the West Antarctic Ice Sheet and tidewater‐terminating glaciers in Greenland today, is still limited. In particular, the role of ice stream instabilities and oceanographic dynamics in driving their collapse are poorly constrained beyond observational timescales. Over numerous glaciations during the Quaternary, a marine‐based ice sheet has waxed and waned over the Barents Sea continental shelf, characterized by a number of ice streams that extended to the shelf edge and subsequently collapsed during periods of climate and ocean warming. Increasing availability of offshore and onshore geophysical data over the last decade has significantly enhanced our knowledge of the pattern and timing of retreat of this Barents Sea ice sheet (BSIS), particularly so from its Late Weichselian maximum extent. We present a review of existing geophysical constraints that detail the dynamic evolution of the BSIS through the last glacial cycle, providing numerical modelers and geophysical workers with a benchmark data set with which to tune ice sheet reconstructions and explore ice sheet sensitivities and drivers of dynamic behavior. Although constraining data are generally spatially sporadic across the Barents and Kara Seas, behaviors such as ice sheet thinning, major ice divide migration, asynchronous and rapid flow switching, and ice stream collapses are all evident. Further investigation into the drivers and mechanisms of such dynamics within this unique paleo‐analogue is seen as a key priority for advancing our understanding of marine‐based ice sheet deglaciations, both in the deep past and in the short‐term future.

A flexural isostasy model for the Pleistocene evolution of the Barents Sea bathymetry

“…The youngest glacial history (postSaalian, <0.14 Ma) is relatively well constrained, but little is known about glaciations prior to the Saalian (Svendsen et al, 2004;Knies et al, 2009;Ingólfsson & Landvik, 2013;Patton et al, 2015). Glacial carving led to sediment redistribution over the shelf-continental slope area and left a significant imprint on the Barents Sea shelf in the form of deep troughs and relatively shallow banks.…”

“…A subaerial to shallow marine relief was transformed into a contrasting bathymetry of deep troughs and relatively shallow banks observed at the present (Vorren et al, 1991;Andreassen et al, 2008;Laberg et al, 2010;Ruddiman, 2010). The topographic development of the Barents Sea during this period is often attributed to glacial carving and sediment transport driven by glacial activity (Vorren et al, 1989;Andreassen et al, 2004Andreassen et al, , 2007Patton et al, 2015). Glacially related sediment redistribution resulted in isostatic readjustments of the lithosphere that contributed to 1-2 km of Cenozoic uplift (Nyland et al, 1992;Rasmussen & Fjeldskaar, 1996;Green & Duddy, 2010;Zattin et al, 2016).…”

Arctic cold seeps in marine methane hydrate environments: impacts on shelf macrobenthic community structure offshore Svalbard

“…Cold Arctic water is transported southwards from the northeast Barents Sea, encountering the warmer Atlantic water where it mixes, forming the Polar Front system (Johannessen & Foster 1978, Harris et al 1998. The Barents Sea and western Svalbard were largely covered by glacial ice during the last glacial period and several different postglacial features have been identified on the seafloor, including megascale glacial lineations, grounding zones, wedges and plough marks (Andreassen & Winsborrow 2009, Patton et al 2015. In the central part of Bjørnøyrenna (74°54' N, 27°34' E), a crater field originally described by Solheim & Elverhøi (1993) has been re-surveyed (Andreassen 2013).…”

The Pleistocene contribution to the net erosion and sedimentary conditions in the outer Bear Island Trough, western Barents Sea

“…The Barents Sea ice sheet also reached the western and northern shelf breaks during the Middle Weichselian (70-65 ka, MIS 4). During the Late Weichselian (25-15 ka, MIS 2) the entire Barents Sea was covered by the ice sheet leaving a till unit over large shelf areas [39,51].…”

“…The glacial events that reached both areas lasted much longer in the southeast than in the west ( Table 3). The reason for this difference might be that the oceanic and climatic conditions favoured a thick and relatively stable ice sheet with its centre in the eastern Barents and Kara Seas like during the Weichselian [40,51]. The western Barents Sea shelf on the other hand, was not near the ice centre, but at the ice margin, where relatively thin and unstable ice covered the area only during relatively short time-periods and not as often as in the east [36,51,55,66].…”