Continued meltwater influence on North Atlantic Deep Water instabilities during the early Holocene

摘要

The transition into the Holocene marks the last large, orbitally derived climatic event and ultimately led to the onset of modern oceanic conditions. The influence of this climatic change on North Atlantic Deep Water (NADW) formation and circulation remains ambiguous. High-resolution records from southern Gardar Drift, south of Iceland, show abrupt decreases in benthic foraminiferal delta C-13 values at discrete intervals during the early Holocene, suggesting that NADW shoaled episodically. Intervals of lower delta C-13 values are coincident with higher Delta delta O-18(N). (pachyderma (s)-G. bulloides) and high abundance of lithic grains/g, indicating that these periods also had enhanced surface water stratification, due to increased meltwater in the circum-North Atlantic region. Our new high-resolution planktonic and benthic foraminiferal stable isotopic data show that increased meltwater delivery led to brief reorganizations of deepwater currents. These southern Gardar surface and deep water records indicate that the early Holocene was a period of multiple abrupt climatic events that were propagated to the North Atlantic during the final break up of ice sheets in the Northern Hemisphere, and suggest that some component of the residual early Holocene sea level rise can be attributed to Northern Hemispheric sources. (C) 2014 Elsevier B.V. All rights reserved.