An ice-marginal δ18O record from Barnes Ice Cap, Baffin Island, Canada

Abstract

Barnes Ice Cap, Baffin Island, Canada, is a remnant of the Laurentide ice sheet that separated from it about 8500 years ago. Owing to recession of the ice cap during the Holocene, Pleistocene-age ice is now exposed along the margin in a distinctive bubble-rich white band. δ18O variations across the white ice resemble those in Canadian Arctic ice cores, suggesting that Barnes Ice Cap preserves a climatic record through the last glacial period, possibly reaching back into the previous (Sangamon) interglacial. The δ18O shift at the Wisconsin-Holocene transition (15‰) exceeds that in other Canadian and Greenland records and cannot be explained solely in climatic terms. A steady-state model reconstruction of the Laurentide ice sheet during the Last Glacial Maximum suggests that Late-glacial strata in Barnes Ice Cap originated high up (>2400 m a.s.l.) and far "inland" on the ice sheet, along a ridge that extended between the ancestral Foxe and Keewatin ice domes.