georefid:2011-064708SEDIS 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=10.1130/G31872.12011-01-01publicationgeorefid:2011-064708doi:10.1130/G31872.1Griffith, Elizabeth M.Kent State University, Department of Geology, Kent, OH, United StatesauthorPaytan, AdinaUniversity of California, Santa Cruz, United StatesauthorEisenhauer, AntonLeibniz-Institut fuer Meereswissenschaften (IFM-GEOMAR), GermanyauthorBullen, Thomas D.U. S. Geological Survey, United StatesauthorThomas, EllenYale University, United StatesauthorGeological Society of America (GSA), Boulder, CO, United StatespublisherdocumentHardcopyGeology (Boulder)39 (7)683-686During the Eocene-Oligocene transition (EOT, ca. 34 Ma), Earth's climate cooled significantly from a greenhouse to an icehouse climate, while the calcite (CaCO (sub 3) ) compensation depth (CCD) in the Pacific Ocean increased rapidly. Fluctuations in the CCD could result from various processes that create an imbalance between calcium (Ca) sources to, and sinks from, the ocean (e.g., weathering and CaCO (sub 3) deposition), with different effects on the isotopic composition of dissolved Ca in the oceans due to differences in the Ca isotopic composition of various inputs and outputs. We used Ca isotope ratios (delta (super 44/40) Ca) of coeval pelagic marine barite and bulk carbonate to evaluate changes in the marine Ca cycle across the EOT. We show that the permanent deepening of the CCD was not accompanied by a pronounced change in seawater delta (super 44/40) Ca, whereas time intervals in the Neogene with smaller carbonate depositional changes are characterized by seawater delta (super 44/40) Ca shifts. This suggests that the response of seawater delta (super 44/40) Ca to changes in weathering fluxes and to imbalances in the oceanic alkalinity budget depends on the chemical composition of seawater. A minor and transient fluctuation in the Ca isotope ratio of bulk carbonate may reflect a change in isotopic fractionation associated with CaCO (sub 3) precipitation from seawater due to a combination of factors, including changes in temperature and/or in the assemblages of calcifying organisms.completedIsotope geochemistryStratigraphyalkaline earth metalsbariteCa-44/Ca-40calciumcarbonate compensation depthCenozoicclimate changeDeep Sea Drilling ProjectDSDP Site 574East PacificEoceneEocene-Oligocene boundaryEquatorial Pacificgeochemical cyclegeochemistryIPODisotope fractionationisotope ratiosisotopesLeg 199Leg 85lower Oligocenemarine sedimentsmetalsNorth PacificNortheast PacificOcean Drilling ProgramODP Site 1218OligocenePacific Oceanpaleo-oceanographypaleoclimatologyPaleogenesedimentsstable isotopessulfatesTertiaryupper Eoceneweatheringurn:org.iodp:exp:199urnlargerWorkCitationcampaignurn:org.iodp:exp:85urnlargerWorkCitationcampaignurn:org.iodp:exp:85:site:574urnlargerWorkCitationstudyurn:org.iodp:exp:85urnlargerWorkCitationcampaignurn:org.iodp:exp:199:site:1218urnlargerWorkCitationstudyurn:org.iodp:exp:199urnlargerWorkCitationcampaignEnglishgeoscientificInformation-135.2200-133.19484.12318.5300With GSA Data Repository Item 2011210