Meltwater and Deglaciation, SE Baffin Shelf (NE Margin Laurentide Ice Sheet) Between 13.5 and 7 KA: From O and C Stable Isotopic Data

• Published in: Paleoceanography
• Main Authors: Andrews, J. T., Erlenkeuser, H., Evans, L. W., Briggs, W. M., Jull, A. J. T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2010
• Subjects: Hudson; Hudson Strait; Baffin; Ice Sheet; Neogloboquadrina pachyderma; Planktonic foraminifera
• Online Access: https://oceanrep.geomar.de/id/eprint/36794/; https://oceanrep.geomar.de/id/eprint/36794/1/JTAndrews.pdf; https://doi.org/10.1029/91PA01914

Stable isotopic values on planktonic foraminifera in a suite of cores from basins across the SE Baffin Shelf are used to extract a record of meltwater events during Termination I deglaciation. Resolution and Hatton basins lie on the SE Baffin Shelf at water depths > 500 m, seaward of major conduits for ice drainage from the eastern sector of the Laurentide Ice Sheet (LIS). Accelerator mass spectrometry 14C dates are used to constrain our chronology of events in ten cores. In Resolution Basin, three cores have 14C AMS dates on foraminifera of > 20 ka at their bases; whereas Hatton Basin cores terminate in sediments < 13 kyr. Sedimentation rates varied between 0.1 to 4.5 m/ka. Stable oxygen and carbon isotopic ratios were obtained on 146 samples of the planktonic foraminifera Neogloboquadrina pachyderma (Ehrenberg) sinistral, from seven of the ten cores. No evidence was found to indicate that test morphology or size affected ∂18O. Between 7 and 13.5 ka the surface water on the shelf was on average 1 ‰ lower than the open ocean signal. Significant temporal variations were found in both ∂18O and ∂13C. Evidence for significant low ∂18O events occurred between 13 and 8 ka. The ∂13C record from the planktonic foraminifera suggests a threefold division of events between 13 and 7 ka, with positive values between 10.8 and 13.0 ka, negative values between 9 and 10.8 ka, and positive values from 7 to 9 ka. The ∂18O data suggest the presence of meltwater on the shelf some 3,000 years prior to the first late glacial dates on terrestrial deglaciation (at circa 10.4 ka). “Hudson Strait must be the real key to the importance of the calving process during deglaciation, because it is potentially the largest marine outlet for the Laurentide Ice Sheet and because it leads into the very center of the ice sheet.the rates of calving through Hudson Strait during the period of initial ∂18O rise unfortunately are unknown.”