georefid:2010-071253SEDIS 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=2010-0712532008-01-01publicationgeorefid:2010-071253Miller, KennethRutgers University, United StatesauthorBrowning, JamesRensselaer Polytechnic Institute, United StatesauthorKatz, MiriamUniversity of Oregon, United StatesauthorWright, JamesauthorAubry, Marie-PierreauthorWade, BridgetauthorCramer, BenjaminauthorKulpecz, AndrewauthorRosenthal, Yairauthor[International Geological Congress], [location varies], InternationalpublisherdocumentHardcopyIn: Anonymous, 33rd international geological congress; abstracts33The St. Stephens Quarry, Alabama (SSQ) outcrop and corehole offer a unique opportunity to evaluate the largest global climate cooling event of the Cenozoic ( nearly equal 33.8-33.5 Ma; latest Eocene-earliest Oligocene) in which warm, high CO2 greenhouse conditions gave way to the icehouse climates that still prevail today. We integrate upper Eocene-lower Oligocene lithostratigraphic, magnetostratigraphic, biostratigraphic, stable isotopic, Mg/Ca, benthic foraminiferal faunal, downhole log, and sequence stratigraphic studies from the SSQ corehole, that provides a superior record to the adjacent outcrop because of limited weathering. The SSQ succession is dissected by hiatuses associated with sequence boundaries: North Twistwood Creek-Cocoa (35.4-35.9 Ma), mid-Pachuta (33.9-35.0 Ma), Shubuta-Bumpnose (lowermost Oligocene; nearly equal 33.6 Ma), Mint Spring-Red Bluff (33.0 Ma), Byram-Glendon (30.5-31.7 Ma), and Bucatunna-Chickasawhay (the famed mid-Oligocene fall; nearly equal 30.2 Ma). Here, we integrate three proxies (ae18O, Mg/Ca, sequence stratigraphy) from SSQ with deep-sea Sites 522 (South Atlantic) and 1218, (Pacific) ae18O and Mg/Ca records to delineate for the first time the three components of the greenhouse-to-icehouse transition (cooling, ice-volume increase, and sea-level fall). A nearly equal 1 0/00 ae18O increase in the SSQ corehole is correlated to the global earliest Oligocene (Oi1) event using magnetobiostratigraphy; this increase is associated with the Shubuta-Bumpnose contact, an erosional surface, and a biofacies shift in the corehole, providing a first-order correlation between ice growth and a sequence boundary that indicates a sea-level fall. A precursor ae18O increase of 0.50/00 (33.8 Ma, mid-Chron C13r) at SSQ correlates with a 0.50/00 increase in the deep Pacific and Atlantic Ocean. Our comparisons reveal that the Eocene-Oligocene transition occurred in two to three steps, with increasing influence by ice volume relative to cooling. In total, ice sheets grew to nearly equal 125% larger than they are today, with an associated nearly equal 105 m relative sea-level ( nearly equal 67 m eustatic) fall. Our study establishes the relationships among ice volume, ae18O, and sequences: a latest Eocene cooling and minor ice-volume event was followed by an earliest Oligocene ice-volume and cooling event that lowered sea-level and formed a sequence boundary during the early stages of eustatic fall.completedStratigraphyAlabamaalkaline earth metalsAngola BasinAtlantic Oceanbiostratigraphyboreholescalciumcarbon dioxideCenozoicDeep Sea Drilling ProjectDSDP Site 522East PacificEoceneEquatorial Pacificeustacygreenhouse effectice sheetsicehouse effectIPODisotope ratiosisotopesLeg 199Leg 73lower OligocenemagnesiummagnetostratigraphymetalsMg/CaNorth PacificNortheast PacificO-18/O-16Ocean Drilling ProgramODP Site 1218OligoceneoxygenPacific OceanpaleoclimatologyPaleogeneSaint Stephens Quarrysea-level changessequence stratigraphySouth Atlanticstable isotopesTertiaryUnited Statesupper Eoceneurn:org.iodp:exp:199urnlargerWorkCitationcampaignurn:org.iodp:exp:73urnlargerWorkCitationcampaignurn:org.iodp:exp:73:site:522urnlargerWorkCitationstudyurn:org.iodp:exp:73urnlargerWorkCitationcampaignurn:org.iodp:exp:199:site:1218urnlargerWorkCitationstudyurn:org.iodp:exp:199urnlargerWorkCitationcampaignEnglishgeoscientificInformation-135.22008.0000-30.000035.0000AlabamaAngola Basin