Reconstructing Holocene Laurentide Ice Sheet discharge and ocean temperature in the western Labrador Sea
Abstract
As recorded in Greenland ice core temperature δ18O records, the 8.2 ka Cold Event stands out as the largest abrupt climate anomaly in the Holocene, presumably forced by the drainage of Glacial Lake Agassiz into the Labrador Sea (~8.4 ka) after the collapse of the Laurentide Ice Sheet (LIS) over Hudson Bay and attendant reduction in North Atlantic overturning strength. However, a prominent freshwater signal has yet to be clearly identified in the Labrador Sea, possibly due to the competing effect of temperature on foraminifera test δ18O. Existing δ18O records from the western Labrador Sea do show light anomalies between 9.5 and 8.6 ka, but increase at the start of the presumed lake drainage event ~8.4 ka. We will present new grain size, planktonic Mg/Ca-based temperature and δ18O of seawater records to reconstruct ice rafting, surface ocean temperature and concurrent LIS meltwater history, respectively, for the Labrador Sea through the Holocene. Our percent sand record suggests several ice rafting events (15-20 % sand) between 10 and 9 ka during the Noble Inlet LIS re-advance in Hudson Strait and a large peak in sand output (25-27 % sand) at ~8.4 ka coincident with the increase in foraminifera δ18O. We will test if cooling masked a large freshwater signal in foraminifera δ18O at the timing of the Lake Agassiz drainage, thereby providing insight into the sensitivity of the North Atlantic to climate perturbations and freshwater flux.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMPP41B1632H
- Keywords:
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- 0720 CRYOSPHERE / Glaciers;
- 1050 GEOCHEMISTRY / Marine geochemistry;
- 1605 GLOBAL CHANGE / Abrupt/rapid climate change;
- 1616 GLOBAL CHANGE / Climate variability