Early arrival of Southern Source Water in the deep North Atlantic prior to Heinrich event 2
Article first published online: 25 JUN 2011
Copyright 2011 by the American Geophysical Union.
Volume 26, Issue 2, June 2011
How to Cite
2011), Early arrival of Southern Source Water in the deep North Atlantic prior to Heinrich event 2, Paleoceanography, 26, PA2101, doi:10.1029/2011PA002114., and (
- Issue published online: 25 JUN 2011
- Article first published online: 25 JUN 2011
- Manuscript Accepted: 31 MAY 2011
- Manuscript Revised: 25 MAY 2011
- Manuscript Received: 10 JAN 2011
- Fe-Mn oxyhydroxides;
- Heinrich event;
- Nd isotopes;
 The Atlantic Meridional Overturning Circulation (AMOC) plays an important role in the Northern Hemisphere climate system. Significant interest went into the question of how excessive freshwater input through melting of continental ice can affect its overturning vigor and, hence, heat supply, to higher northern latitudes. Such forcing can be tested by investigating its behavior during extreme iceberg discharge events into the open North Atlantic during the last glacial period, the so-called Heinrich events (HE). Here we present neodymium (Nd) isotope compositions of past seawater, a sensitive chemical water mass tag, extracted from sediments of Ocean Drilling Program Site 1063 in the western North Atlantic (Bermuda Rise), covering the period surrounding HE 2, the Last Glacial Maximum, and the early deglaciation. These data are compared with a record of the kinematic circulation tracer (231Pa/230Th)xs extracted from the same sediment core. Both tracers indicate significant circulation changes preceding intense ice rafting during HE 2 by almost 2 kyr. Moreover, the Nd isotope record suggests the presence of deeply ventilating North Atlantic Deep Water early during Marine Isotope Stage 2 until it was replaced by Southern Source Water at ∼27 ka. The early switch to high (Pa/Th)xs and radiogenic ɛNd in relation to intensified ice rafting during HE 2 suggests that ice rafting into the open North Atlantic during major HE 2 was preceded by an early change of the AMOC. This opens the possibility that variations in AMOC contributed to or even triggered the ice sheet instability rather than merely responding to it.