Sediment core records, recovered by the CCGS Amundsen as part of a 2016 ArcticNet cruise in M’Clintock Channel in the central Canadian Arctic Archipelago (CAA), provide a unique sedimentary history of large-scale Early Holocene ice shelf occupation and collapse. Well-constrained by foraminiferal radiocarbon dates and taken together with detailed flow-set mapping and chronologies on adjacent Victoria and Prince of Wales islands, the record illustrates a late-stage floating ice advance of over 375 km (equating to an ice shelf area >55,000 km2) from the M’Clintock Ice Stream draining the southward retreating margin of the deglaciating northwestern sector of the Laurentide Ice Sheet (NW LIS). Ice shelf advance occurred after 10.5 cal BP followed by sequential retreat from its north maximum, some one hundred cal. years later. By 9.6 cal ka BP the ice shelf had completely collapsed and ice retreated rapidly back on to mainland Canada.

Ice rafted debris and foraminiferal assemblages from calving margin and post-ice shelf glacimarine facies in the core record confirm that the formation and subsequent demise of the M’Clintock Ice Shelf resulted in the irreparable draw-down and destabilisation of the NW LIS and permitted the commencement of marine throughflow from Amundsen Gulf and the Arctic Ocean into the central CAA and the final establishment of similar-to-modern oceanic circulation by 8.8 cal ka BP. Those same foraminiferal assemblages further implicate warm Arctic Ocean Intermediate Water of re-circulated Atlantic origin, penetrating southwards from Viscount Melville Sound, as the primary driver of ice shelf retreat and collapse.

This record adds to the growing inventory of extensive and often catastrophic deglacial ice shelves identified from the Late Pleistocene and Early Holocene of the CAA and suggests that not only were short-lived large-scale ice shelves common during deglaciation, but that they may have been ubiquitous in this complex archipelago setting. This geological record of widespread ice retreat and ice shelf instability at the end of the Last Glaciation serves as a source of vital analogues for ongoing and future human-induced high latitude climate change and can provide important constraints on modelled forecasts of Antarctic ice shelf behaviour under rising sea levels and warming ocean conditions.