{"xmlId":"68310","NOAAStudyId":"27750","studyName":"Southwest Atlantic DSDP516 4Ma Nd Isotope Data","doi":"https://doi.org/10.25921/mtwm-8e25","uuid":"fa505fd6-9927-4c14-826f-30c9f7146a64","dataPublisher":"NOAA","contactInfo":{"type":"CONTACT INFORMATION","shortName":"DOC/NOAA/NESDIS/NCEI","longName":"National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce ","address":"325 Broadway, E/NE31","city":"Boulder","state":"CO","postalCode":"80305-3328","country":"USA","dataCenterUrl":"https://www.ncei.noaa.gov/products/paleoclimatology","email":"paleo@noaa.gov","phone":"828-271-4800","fax":null,"constraints":"Please cite original publication, online resource, dataset and publication DOIs (where available), and date accessed when using downloaded data. If there is no publication information, please cite investigator, title, online resource, and date accessed. The appearance of external links associated with a dataset does not constitute endorsement by the Department of Commerce/National Oceanic and Atmospheric Administration of external Web sites or the information, products or services contained therein. For other than authorized activities, the Department of Commerce/NOAA does not exercise any editorial control over the information you may find at these locations. These links are provided consistent with the stated purpose of this Department of Commerce/NOAA Web site."},"dataType":"PALEOCEANOGRAPHY","investigators":"Karas, C.; Goldstein, S.L.; deMenocal, P.B.","investigatorDetails":[{"firstName":"Cyrus","lastName":"Karas","initials":"C.","orcId":"0000-0002-7436-5016"},{"firstName":"Steven","lastName":"Goldstein","initials":"S.L.","orcId":"0000-0001-7252-8064"},{"firstName":"Peter","lastName":"deMenocal","initials":"P.B.","orcId":"0000-0002-7191-717X"}],"version":"1.0","funding":[{"fundingAgency":"Deutsche Forschungsgemeinschaft (DFG)","fundingGrant":"KA3461/1-2"}],"studyNotes":"Neodymium isotopes of Fe-Mn-oxyhydroxide encrusted foraminifera, benthic foraminiferal Mg/Ca and BWT, and stable isotopes from southwest Atlantic DSDP Site 516/516A for the past 4 million years","onlineResourceLink":"https://www.ncei.noaa.gov/access/paleo-search/study/27750","difMetadataLink":"https://www.ncei.noaa.gov/pub/data/metadata/published/paleo/dif/xml/noaa-ocean-27750.xml","isoMetadataLink":"https://www.ncei.noaa.gov/pub/data/metadata/published/paleo/iso/xml/noaa-ocean-27750.xml","originalSource":null,"dataTypeInformation":"https://www.ncei.noaa.gov/products/paleoclimatology/paleoceanography","studyCode":null,"scienceKeywords":null,"reconstruction":"Y","contributionDate":"2019-09-23","entryId":"noaa-ocean-27750","earliestYearBP":4670000,"mostRecentYearBP":70000,"earliestYearCE":-4668050,"mostRecentYearCE":-68050,"publication":[{"author":{"name":"Cyrus Karas, Steven L. Goldstein, Peter B. deMenocal"},"pubYear":2019,"title":"Evolution of Antarctic Intermediate Water during the Plio-Pleistocene and implications for global climate: Evidence from the South Atlantic","journal":"Quaternary Science Reviews","volume":"223","edition":"105945","issue":null,"pages":null,"reportNumber":null,"citation":"Cyrus Karas, Steven L. Goldstein, Peter B. deMenocal. 2019. Evolution of Antarctic Intermediate Water during the Plio-Pleistocene and implications for global climate: Evidence from the South Atlantic. Quaternary Science Reviews, 223, 105945. doi: 10.1016/j.quascirev.2019.105945","type":"publication","identifier":{"type":"doi","id":"10.1016/j.quascirev.2019.105945","url":"http://dx.doi.org/10.1016/j.quascirev.2019.105945"},"abstract":"Formed in the Southern Ocean, Antarctic Intermediate Water (AAIW) plays a fundamental role in the modern climate system as an important sink for atmospheric CO2, and as a mid-depth conduit supplying nutrient-rich waters to subtropical and tropical upwelling regions. During the transition from warm Pliocene 'greenhouse' conditions to Pleistocene 'icehouse' conditions around 3 Ma, model simulations suggest dramatic circulation changes in the Southern Ocean AAIW formation region due to cooling and expanded sea ice cover around Antarctica. However, the history and properties of AAIW over this time period are still poorly understood. Here, we trace AAIW source water provenance, temperature, and salinity changes over the last 4 Myr using Nd isotopes of Fe-Mn-oxyhydroxide encrusted foraminifera, benthic foraminiferal Mg/Ca, and stable isotopes from southwest Atlantic DSDP Site 516. Our results show that modern AAIW properties emerged gradually over the last 3 Myr, as evidenced by gradual cooling (6C) and freshening of intermediate waters. Over this same interval, ENd-values decrease and diverge away from those of Pacific-sourced waters and converge on values of present-day Circumpolar Deep Water (CDW). These observations are in accordance with model simulations indicating increased deep vertical mixing at the Polar Front associated with sea ice extension. These modified AAIW source waters penetrated increasingly northward into the Atlantic at intermediate depths, enhancing nutrient supply and contributing to surface cooling along subtropical coastal upwelling sites. These circulation changes may have facilitated ocean CO2 storage, providing a positive feedback amplifying global cooling and intensification of Northern Hemisphere Glaciation.","pubRank":"1"}],"site":[{"NOAASiteId":"57021","siteName":"DSDP 516A","siteCode":null,"mappable":"Y","locationName":"Ocean>Atlantic Ocean>South Atlantic Ocean","geo":{"geoType":"Feature","geometry":{"type":"POINT","coordinates":["-30.2833","-35.2833"]},"properties":{"southernmostLatitude":"-30.2833","northernmostLatitude":"-30.2833","westernmostLongitude":"-35.2833","easternmostLongitude":"-35.2833","minElevationMeters":"-1313","maxElevationMeters":"-1313"}},"paleoData":[{"dataTableName":"Karas2019d18O","NOAADataTableId":"40157","earliestYear":3890000,"mostRecentYear":70000,"timeUnit":"cal yr 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