georefid:2013-035835SEDIS Publication Catalogue

ana.macario@awi.de

http://sedis.iodp.org/pub-catalogue/informationpointOfContact2013-07-08T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=10.1029/2011PA0021142011-01-01publicationgeorefid:2013-035835doi:10.1029/2011PA002114Gutjahr, MarcusUniversity of Bristol, Department of Earth Sciences, Bristol, United KingdomauthorLippold, JoergUniversity of Heidelberg, GermanyauthorAmerican Geophysical Union, Washington, DC, United StatespublisherdocumentHardcopyPaleoceanography26 (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.completedQuaternary geologyactinidesalkaline earth metalsAtlantic Meridional Overturning CirculationAtlantic OceanBermuda RisecalciumCenozoicchemostratigraphychronostratigraphycoresdeglaciationfresh waterHeinrich eventsice raftingisotope ratiosisotopesLeg 172marine sedimentsmeltwatermetalsNd-144/Nd-143neodymiumNorth AtlanticNorth Atlantic Deep WaterO-18/O-16ocean circulationOcean Drilling ProgramODP Site 1063oxygenPa-231/Th-230paleo-oceanographyPleistoceneprotactiniumQuaternaryradioactive isotopesrare earthssedimentsstable isotopesthoriumTi/Catitaniumupper Pleistoceneurn:org.iodp:exp:172urnlargerWorkCitationcampaignurn:org.iodp:exp:172:site:1063urnlargerWorkCitationstudyurn:org.iodp:exp:172urnlargerWorkCitationcampaignEnglishgeoscientificInformation-57.3654-57.365433.411133.4111