10 Be dating the last deglaciation of Bjørnøya, Svalbard

The retreat of the Barents Sea Ice Sheet was a major event in the last deglaciation of the Arctic. Numerous studies document the fine details of the seafloor that reveal a highly dynamic ice sheet somewhat analogous to the West Antarctic Ice Sheet. Despite detailed records of the Barents Sea Ice Sheet’s dynamics, comparatively few studies have provided chronological control that constrains its history of final collapse. We report cosmogenic 10Be exposure ages from 14 glacial erratics, nine moraine boulders and one bedrock surface from southern Bjornoya, an island situated in the Barents Sea between Svalbard and Norway. 17 of 24 samples average 12.4 ± 0.5 ka with no significant relationship between age and elevation. We interpret the ages to represent the time when Bjornoya, and the shallow Spitsbergenbanken upon which it sits, became finally deglaciated following break up of the Barents Sea Ice Sheet. The timing of deglaciation, overlapping with the early Younger Dryas, suggests that Younger Dryas climate change did not reverse overall glacier recession, although we cannot rule out a stillstand or re-advance during the early Younger Dryas.