Sediments, sedimentation rates, and environments, southeast Baffin Shelf and northwest Labrador Sea, 8–26 ka

Abstract

Ten 14C-dated cores are described from the Labrador Sea, continental slope, and Hatton and Resolution basins on the southeast Baffin Shelf. Based on sharply defined detrital carbonate layers in the Labrador Sea cores, we propose that the Laurentide Ice Sheet reached the shelf break at both 20 and 15 14C ka (24.3 and 18.2 sidereal ka) and contributed significant sediment to the northwest Labrador Sea both times; the flux was ± 720 kg/(m2∙ka) during these periods of maximum ice extent. The Laurentide Ice Sheet retreated from its 15 ka position at the shelf break to the inner shelf between 14 and 12 14C ka. Ice-proximal conditions, recognized by relatively light δ18O on near-surface planktonic foraminifera, high detrital carbonate, and benthic foraminiferal faunas (dominated by Elphidium excavatum forma clavata; Cassidulina reniforme), prevailed until at least 10 14C ka. The ice readvanced toward Resolution Basin and across part of Hatton Basin at 11 14C ka. Accelerator mass spectrometry dates on core tops indicate that deposition on the shelf virtually ceased by 7 ka and was very low in the northwest Labrador Sea throughout the Holocene. Downcore accelerator mass spectrometry dates indicate that during deglaciation, the loci of depocentres shifted in response to changes in the position of the ice margin. On the southeast Baffin Island shelf net sediment fluxes at the sea floor reached values of over 3000 kg/(m2∙ka) between 12 and 10 14C ka, of which nearly half was detrital carbonate, principally calcite.