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The Cenozoic development of the Scotia Sea and opening of Drake Passage evolved in a complex tectonic setting with sea-floor spreading accompanied by the dispersal of continental fragments and the creation of rifted oceanic basins. The post-Eocene tectonic setting of the Scotia Sea is relatively well established, but Late Mesozoic paleo-locations of many continental fragments prior to dispersal are largely unknown, with almost no geological control on the submerged banks. Detrital zircon analysis of dredged metasedimentary rocks of Bruce Bank from the South Scotia Ridge demonstrates a geological continuity with the South Orkney microcontinent (SOM) and also a clear geological affinity with the Trinity Peninsula Group metasedimentary rocks of the Antarctic Peninsula and components of the Cordillera Darwin Metamorphic Complex of Tierra del Fuego. Kinematic modelling indicate an Antarctic Plate origin for Bruce Bank and the SOM is the most plausible setting, prior to translation to the Scotia Plate during Scotia Sea opening.

New information is presented on the configuration of the northern Barents Sea Ice Sheet (BSIS) during the last glacial and deglaciation (21–11.5 ka). The glacial dynamics of the BSIS that we discuss are based on clay-mineral compositions of subglacial tills and a distinct kaolinite source in the central Barents Sea where previous workers have placed a large, single ice dome for the last glacial BSIS. Our results, which appear to show that subglacial sediments were sourced locally, suggest that the BSIS consisted at least temporarily of multiple domes and may have been more dynamic than previously thought. New radiocarbon dates are presented along with new ice-extent reconstructions for 16.5–15, 14, 13.5 and 11.5 ka. Our reconstructions add information to previous regional and continental-scale efforts in areas east of Svalbard. Ice retreat in the northern Barents Sea progressed as follows. (i) 19–16.5 ka. Major calving led to dynamic thinning in shelf troughs and was accompanied by significant ice-sheet thinning inland as a result of ice drawdown. (ii) 16.5–15 ka. Rapid ice-margin retreat of between 75–100 km occurred, via lift-off and iceberg calving, in Hinlopen and Kvitøya troughs, as well as major retreat (>300 km) in Franz Victoria Trough (FVT) further east. (iii) 15–13.5 ka. Retreat progressed westwards from the FVT towards Svalbard with troughs east of Svalbard (Kvitøya, Olga, and Erik Eriksen) mostly ice-free by 13.5 ka. (iv) 13.5–11.5 ka. Ice retreated gradually towards residual ice masses on Svalbard, Kong Karls Land and possibly Storbanken. Our data require a modification of earlier views of the BSIS because they point toward a more dynamic ice sheet and decay that, once initiated at the shelf break, was dominated by the withdrawal of ice from the FVT that progressed westwards towards the Svalbard archipelago.

Ice stream bed topography contains key evidence for the ways ice streams interact with, and are potentially controlled by, their beds. Here we present the first application of two–dimensional Fourier analysis to 22 marine and terrestrial topographies from 5 regions in Antarctica and Canada, with and without mega-scale glacial lineations (MSGLs). We find that the topography of MSGL-rich ice stream sedimentary beds is characterized by multiple, periodic wavelengths between 300 and 1200 m and amplitudes from decimeters to a few meters. This periodic topography is consistent with the idea that instability is a key element to the formation of MSGL bedforms. Dominant wavelengths vary among locations and, on one paleo ice stream bed, increase along the direction of ice flow by 1.7±0.52% km-1. We suggest that these changes are likely to reflect pattern evolution via downstream wavelength coarsening, even under potentially steady ice stream geometry and flow conditions. The amplitude of MSGLs is smaller than that of other fluvial and glacial topographies, but within the same order of magnitude. However, MSGLs are a striking component of ice stream beds because the topographic amplitude of features not aligned with ice flow is reduced by an order of magnitude relative to those oriented with the flow direction. This study represents the first attempt to automatically derive the spectral signatures of MSGLs. It highlights the plausibility of identifying these landform assemblages using automated techniques and provides a benchmark for numerical models of ice stream flow and subglacial landscape evolution.

Greenland's bed topography is a primary control on ice flow, grounding line migration, calving dynamics and subglacial drainage. Moreover, fjord bathymetry regulates the penetration of warm Atlantic Water (AW) that rapidly melts and undercuts Greenland's marine-terminating glaciers. Here, we present a new compilation of Greenland bed topography that assimilates seafloor bathymetry and ice thickness data through a mass conservation (MC) approach. A new 150-m horizontal resolution bed topography/bathymetric map of Greenland is constructed with seamless transitions at the ice/ocean interface, yielding major improvements over previous datasets, particularly in the marine-terminating sectors of northwest and southeast Greenland. Our map reveals the total sea level potential of the Greenland Ice Sheet is 7.42±0.05 m, which is 7 cm greater than previous estimates. Furthermore, it explains recent calving front response of numerous outlet glaciers and reveals new pathways by which AW can access glaciers with marine-based basins, thereby highlighting sectors of Greenland that are most vulnerable to future oceanic forcing.