Magnetic susceptibility of late quaternary marine sediments, Frobisher Bay, N.W.T.: An indicator of changes in provenance and processes

Abstract

Twelve piston cores from the floor of Frobisher Bay and adjacent inner portion of the SE Baffin Shelf, show Holocene variations in volume magnetic susceptibility, K, over three orders of magnitude (1–1000 × 10 −5 SI). The variations are a function of changes in provenance, in the inputs of detrital carbonates and organic carbon and grain size. The chronology of depositional events within this region, marginal to the Laurentide Ice Sheet, has been clarified by 14C AMS dates on marine shells or foraminifera. Correlations between cores are further refined by the use of core segmentation and ‘sequence slotting’, algorithms. Two well-defined magnetic susceptibility units are recognized during the last 10,000 years, which are further sub-divided into smaller events which are coeval with intervals of glacial re-advance and retreat. Mapping magnetic susceptibility in time/distance space indicates a double ‘plume’ of high magnetic susceptibility which occurred in the outer bay between 8–10 ka. This plume appears to be associated with a N-NE flow of ice across the tip of SE Baffin Island from Hudson Strait (possibly from Labrador-Ungava?).