Gutjahr, Marcus and Lippold, Joerg (2011): Early arrival of southern source water in the deep North Atlantic prior to Heinrich event 2

Leg/Site/Hole:
ODP 172
ODP 172 1063
Identifier:
2013-035835
georefid

10.1029/2011PA002114
doi

Creator:
Gutjahr, Marcus
University of Bristol, Department of Earth Sciences, Bristol, United Kingdom
author

Lippold, Joerg
University of Heidelberg, Germany
author

Identification:
Early arrival of southern source water in the deep North Atlantic prior to Heinrich event 2
2011
Paleoceanography
American Geophysical Union, Washington, DC, United States
26
2
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 ( (super 231) Pa/ (super 230) Th) (sub 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 approximately 27 ka. The early switch to high (Pa/Th) (sub xs) and radiogenic epsilon (sub Nd) 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.
English
Serial
Coverage:Geographic coordinates:
North:33.4111
West:-57.3654East: -57.3654
South:33.4111

Quaternary geology; actinides; alkaline earth metals; Atlantic Meridional Overturning Circulation; Atlantic Ocean; Bermuda Rise; calcium; Cenozoic; chemostratigraphy; chronostratigraphy; cores; deglaciation; fresh water; Heinrich events; ice rafting; isotope ratios; isotopes; Leg 172; marine sediments; meltwater; metals; Nd-144/Nd-143; neodymium; North Atlantic; North Atlantic Deep Water; O-18/O-16; ocean circulation; Ocean Drilling Program; ODP Site 1063; oxygen; Pa-231/Th-230; paleo-oceanography; Pleistocene; protactinium; Quaternary; radioactive isotopes; rare earths; sediments; stable isotopes; thorium; Ti/Ca; titanium; upper Pleistocene;

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