Along-slope variations in sediment lithofacies and depositional processes since the Last Glacial Maximum on the northeast Baffin margin, Canada

Abstract

Twelve piston cores were used to characterize late Quaternary lithofacies, depositional processes and deglacial history along the Baffin Bay slope between Lancaster Sound and Home Bay. Core investigations show four distinct laterally correlatable lithofacies along the slope – basal and upper diamicton, laminated red brown mud, tan carbonate gravelly, sandy mud and bioturbated brown mud. Basal diamicton largely represents glacigenic debris flow deposits during a glacial advance from Baffin Island at ~25 cal ka. The distribution and character of laminated red brown mud suggests a lateral supply to Baffin Bay slope from ice-proximal meltwater plumes and turbidity currents sourced in glacial ice from both Baffin Bay shelf and Home Bay between 41.5 cal ka to ~14.2 cal ka. An upper diamicton records a lesser, localized glacial advance that ended at about 14.2 cal ka. Tan carbonate mud events represent ice-rafted, enhanced detrital carbonate delivery to the slope between ~25 cal ka and ~11 cal ka. A gradual thinning of these events, from northern to southern Baffin Bay, corroborates a northern Baffin Bay, Lancaster Sound or Nares Strait iceberg source. Proglacial facies seaward of Home Bay contain beds with slightly elevated detrital carbonate that may represent the distal edge of carbonate ice-rafted from Lancaster Sound. Baffin Bay is a type example of a polar glacial basin in which direct glacial supply predominates over the effects of glacial meltwater. As a result, axial supply from the large ice streams north of Baffin Bay (particularly Lancaster Sound) is dominant in the Baffin Bay basin and lateral supply from smaller ice streams on Baffin Island predominates on the NE Baffin Slope.