Growth of the Laurentide and Innuitian ice sheets during MIS 5 recorded in distal marine sediment

Three long cores from Flemish Cap and Orphan Knoll, offshore southeastern Canada, contain discrete units of detrital carbonates that are coeval with Hudson Strait Heinrich (HS–H) events 1 to 6 (16–60 ka BP), but they also contain similar sediments that date from Marine Isotope Stage (MIS) 5. These distal detrital carbonate layers require the presence of substantial ice sheets over Eastern Canada. To validate these important paleoclimatic and glaciological implications, we derive the provenance of sediments deposited during MIS 5 using both gravel provenance and a four-source sediment unmixing model consisting of 13 non-clay and clay mineral weight %s of the <2 mm fraction of samples from Hudson Strait, Ungava Bay/Labrador Trough, Cumberland Sound, and detrital carbonate facies in Baffin Bay. The H 8, 8a, 9 and 10 sediments at Flemish Cap and Orphan Knoll are dominated by Hudson Strait sources but with contributions from Baffin Bay. During MIS 5, the Innuitian and Laurentide ice sheets eroded carbonate outcrops on Baffin Island and the Canadian Arctic Islands and Channels, delivering ice rafted dolomite-dominated carbonate sediments. Our sites are ∼1900 km south of the putative source in Hudson Strait and ∼3000 km from northern Baffin Bay and the provenance data requires the rapid build-up of the Laurentide and Innuitian ice sheets during MIS 5d, with an active ice stream in Hudson Strait contributing significant volumes of ice-rafted debris. Our results validate benthic foraminiferal δ18O stacks that require substantial reductions in global sea levels during MIS 5.