georefid:2011-038843SEDIS Publication Catalogue

ana.macario@awi.de

http://sedis.iodp.org/pub-catalogue/informationpointOfContact2011-07-06T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=10.1130/G31651.12011-01-01publicationgeorefid:2011-038843doi:10.1130/G31651.1Kleiven, Helga F.University of Bergen, Department of Earth Science, Bergen, NorwayauthorHall, I. R.Cardiff University, United KingdomauthorMcCave, I. N.University of Cambridge, United KingdomauthorKnorr, G.Bjerknes Centre for Climate Research, NorwayauthorJansen, E.authorGeological Society of America (GSA), Boulder, CO, United StatespublisherdocumentHardcopyGeology (Boulder)39 (4)343-346Abrupt changes in the strength of the Atlantic Meridional Overturning Circulation (comprising northward flow of warm water and a cold southward return flow) are implicated in abrupt climate changes in the late Pleistocene. A sensitive place to assess this circulation is in the cold return flow of Deep Western Boundary Currents. Here, in records of flow speed and isotopic composition of surface and bottom waters from a Deep Western Boundary Current location near the northern source of North Atlantic Deep Water, we show both orbital and millennial-scale coupling between deep ocean flow and climate in the middle Pleistocene (0.75-0.87 Ma), when the boundary conditions in terms of the mean state and amplitude of climate change were different from more recent periods. The coupling appears as a phased series of events initiated by reduced vertical density gradients and initial ventilation of deep waters. The occurrence of these events in interglacials during the middle Pleistocene suggests that the millennial-scale climate variability in the North Atlantic was more pronounced at that time than previously thought. This demonstrates that, given the right boundary conditions, rapid climate shifts can also occur during relatively warm climate conditions.completedQuaternary geologyAnomalinidaeAtlantic Meridional Overturning CirculationAtlantic Oceanbenthic taxaboundary conditionsC-13/C-12carbonCassidulinaceaCeara RiseCenozoicCibicidoidesCibicidoides wuellerstorficlastic sedimentsclimate changecorescouplingcurrentsDeep Western Boundary CurrentdriftEquatorial AtlanticForaminiferaGardar DriftGlobigerinaceagrain sizeinterglacial environmentInvertebrataisotope ratiosisotopesLeg 154Leg 162marine sedimentsmicrofossilsmiddle PleistoceneNeogloboquadrinaNeogloboquadrina pachydermaNorth AtlanticNorth Atlantic Deep WaterO-18/O-16ocean currentsOcean Drilling ProgramODP Site 928ODP Site 983oxygenpaleo-oceanographypaleocirculationpaleoclimatologypaleocurrentsplanktonic taxaPleistoceneProtistaQuaternaryReykjanes RidgeRotaliinasedimentsstable isotopesurn:org.iodp:exp:154urnlargerWorkCitationcampaignurn:org.iodp:exp:162urnlargerWorkCitationcampaignurn:org.iodp:exp:154:site:928urnlargerWorkCitationstudyurn:org.iodp:exp:154urnlargerWorkCitationcampaignurn:org.iodp:exp:162:site:983urnlargerWorkCitationstudyurn:org.iodp:exp:162urnlargerWorkCitationcampaignEnglishgeoscientificInformation-43.4453-23.38269.271960.2412With GSA Data Repository Item 2011114