georefid:2003-083434SEDIS Publication Catalogueana.macario@awi.dehttp://sedis.iodp.org/pub-catalogue/informationpointOfContact2011-06-23T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=10.1130/G19800.1<gco:CharacterString>Significant Southern Ocean warming event in the late middle Eocene</gco:CharacterString>2003-01-01publicationgeorefid:2003-083434doi:10.1130/G19800.1Bohaty, Steven M.University of California at Santa Cruz, Earth Sciences Department, Santa Cruz, CA, United StatesauthorZachos, James C.authorGeological Society of America (GSA), Boulder, CO, United StatespublisherdocumentHardcopyGeology (Boulder)31 (11)1017-1020A prominent middle Eocene warming event is identified in Southern Ocean deep-sea cores, indicating that long-term cooling through the middle and late Eocene was not monotonic. At sites on Maud Rise and the Kerguelen Plateau, a distinct negative shift in delta (super 18) O values ( approximately 1.0ppm) is observed ca. 41.5 Ma. This excursion is interpreted as primarily a temperature signal, with a transient warming of 4 degrees C over 600 k.y. affecting both surface and middle-bathyal deep waters in the Indian-Atlantic region of the Southern Ocean. This isotopic event is designated as the middle Eocene climatic optimum, and is interpreted to represent a significant climatic reversal in the midst of middle to late Eocene deep-sea cooling. The lack of a significant negative carbon isotope excursion, as observed during the Paleocene-Eocene thermal maximum, and the gradual rate of high-latitude warming suggest that this event was not triggered by methane hydrate dissociation. Rather, a transient rise in pCO (sub 2) levels is suspected, possibly as a result of metamorphic decarbonation in the Himalayan Orogen or increased ridge/arc volcanism during the late middle Eocene.completedStratigraphyAnomalinidaebenthic taxabiochemistrybiostratigraphyC-13/C-12carbonCassidulinaceaCenozoicchemostratigraphyCibicidoidesclimate changecoresEoceneForaminiferaInvertebrataisotope ratiosisotopesKerguelen PlateauLeg 113Leg 119Leg 120marine sedimentsMaud Risemicrofossilsmiddle EoceneNuttallidesO-18/O-16Ocean Drilling ProgramODP Site 689ODP Site 690ODP Site 738ODP Site 744ODP Site 748oxygenpaleo-oceanographypaleoclimatologyPaleogenepaleogeographypaleotemperatureProtistaRotaliinasedimentsSouthern Oceanstable isotopesstatistical analysisTertiarytime series analysisWeddell Seaurn:org.iodp:exp:113urnlargerWorkCitationcampaignurn:org.iodp:exp:119urnlargerWorkCitationcampaignurn:org.iodp:exp:120urnlargerWorkCitationcampaignurn:org.iodp:exp:113:site:689urnlargerWorkCitationstudyurn:org.iodp:exp:113urnlargerWorkCitationcampaignurn:org.iodp:exp:113:site:690urnlargerWorkCitationstudyurn:org.iodp:exp:113urnlargerWorkCitationcampaignurn:org.iodp:exp:119:site:738urnlargerWorkCitationstudyurn:org.iodp:exp:119urnlargerWorkCitationcampaignurn:org.iodp:exp:119:site:744urnlargerWorkCitationstudyurn:org.iodp:exp:119urnlargerWorkCitationcampaignurn:org.iodp:exp:120:site:748urnlargerWorkCitationstudyurn:org.iodp:exp:120urnlargerWorkCitationcampaignEnglishgeoscientificInformation1.121882.4715-65.0938-58.2627With GSA Data Repository Item 2003148