Glacial landforms reveal dynamic ice-sheet behaviour along the mid-Norwegian margin during the last glacial-deglacial cycle

Abstract

The analysis of glacial landforms preserved on mid- and high-latitude continental margins provides insights into the patterns and processes of sedimentation beneath contemporary ice sheets and aids predictions of the future resilience of ice sheets to ocean and atmospheric drivers of change. However, most previous high-resolution investigations of submarine glacial landforms have utilised data that are focused only on relatively small areas of the seafloor. Here we use an extensive database of high-resolution marine-geophysical data to map and interpret the distribution of glacial landforms over an 80,000 km2 area along a ∼600 km-long section of the mid-Norwegian margin. Our glacial-geomorphological mapping shows that the Scandinavian Ice Sheet displayed highly dynamic behaviour, including readvances and changes in ice-flow direction, during the last glacial-interglacial cycle. The shallow banks briefly became dynamic centres of ice flow during deglaciation, with ice readvances from these banks linked to the loss of ice-sheet buttressing through the early deglaciation of grounded ice in the deeper troughs. The geometry of the continental shelf, especially its troughs and banks, exerted an important control on the pattern of ice-sheet retreat. The distribution of small grounding-zone wedges shows that frequent, small-magnitude still-stands or readvances within overall ice-stream retreat were prevalent on prograding slopes that limited the flux of ice across the grounding zone. Although the pattern of ice-sheet retreat along the mid-Norwegian margin is now relatively well-understood, future marine sediment coring efforts are needed to better constrain the timing of these deglacial events.