georefid:2013-005636SEDIS 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=10.1029/2011PA0022592012-01-01publicationgeorefid:2013-005636doi:10.1029/2011PA002259Koch, Mirjam C.Goethe-Universitaet Frankfurt, Institut fuer Geowissenschaften, Frankfurt, GermanyauthorFriedrich, OliverauthorAmerican Geophysical Union, Washington, DC, United StatespublisherdocumentHardcopyPaleoceanography27 (2)During the latest Cretaceous cooling phase, a positive shift in benthic foraminiferal delta (super 18) O values lasting about 1.5 Myr (71.5-70 Ma) can be observed at a global scale (Campanian-Maastrichtian Boundary Event, CMBE). This delta (super 18) O excursion is interpreted as being influenced by a change in intermediate- to deep-water circulation or by temporal build-up of Antarctic ice sheets. Here we test whether benthic foraminiferal assemblages from a southern high-latitudinal site near Antarctica (ODP Site 690) are influenced by the CMBE. If the delta (super 18) O transition reflects a change in intermediate- to deep-water circulation from low-latitude to high-latitude water masses, then this change would result in cooler temperatures, higher oxygen concentration, and possibly lower organic-matter flux at the seafloor, resulting in a major benthic foraminiferal assemblage change. If, however, the delta (super 18) O transition was mainly triggered by ice formation, no considerable compositional difference in benthic foraminiferal assemblages would be expected. Our data show a separation of the studied succession into two parts with distinctly different benthic foraminiferal assemblages. Species dominating the older part (73.0-70.5 Ma) tolerate less bottom water oxygenation and are typical components of low-latitude assemblages. In contrast, the younger part (70.0-68.0 Ma) is characterized by species that indicate well-oxygenated bottom waters and species common in high-latitude assemblages. We interpret the observed change in benthic foraminiferal assemblages toward a well-oxygenated environment to reflect the onset of a shift from low-latitude toward high-latitude dominated intermediate- to deep-water sources. This implies that a change in oceanic circulation was at least a major component of the CMBE.completedStratigraphyIsotope geochemistrybenthic taxaC-13/C-12CampaniancarbonCretaceousdeep-water environmentForaminiferaInvertebrataisotope ratiosisotopesLeg 113Maestrichtianmarine environmentMaud RiseMesozoicmicrofossilsO-18/O-16ocean circulationOcean Drilling ProgramODP Site 690oxygenpaleo-oceanographypaleoenvironmentpaleolatitudeProtistaSenonianSouthern Oceanstable isotopesUpper CretaceousWeddell Seaurn:org.iodp:exp:113urnlargerWorkCitationcampaignurn:org.iodp:exp:113:site:690urnlargerWorkCitationstudyurn:org.iodp:exp:113urnlargerWorkCitationcampaignEnglishgeoscientificInformation1.12181.1218-65.0938-65.0937