georefid:2000-002037SEDIS Publication Catalogueana.macario@awi.dehttp://sedis.iodp.org/pub-catalogue/informationpointOfContact2011-06-23T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=2000-002037<gco:CharacterString>Unusual Oligocene Braarudosphaera-rich layers of the South Atlantic and their palaeoceanographic implications</gco:CharacterString>1999-01-01publicationgeorefid:2000-002037Peleo-Alampay, Alyssa M.University of the Philippines, National Institute of Geological Sciences, Quezon City, PhilippinesauthorMead, Gregory A.University of Florida, United StatesauthorWei, WuchangUniversity of California at San Diego, United StatesauthorInternational Nannoplankton Association, The Hague, InternationalpublisherdocumentHardcopyJournal of Nannoplankton Research21 (1)17-26The origin of the Oligocene Braarudosphaera layers over large ocean basins has remained a mystery since the question was raised almost three decades ago by the Deep Sea Drilling Project. A micropalaeontological study, coupled with oxygen and carbon isotope data, from Sites 363 and 522 in the S Atlantic Ocean have shed some new light on this question. Our Braarudosphaera abundance data correlate with oxygen isotope curves, suggesting that Braarudosphaera preferred cold waters. Variations in the relative abundance of sphenoliths (warm-water taxa), and longer Coccolithus pelagicus placoliths, also indicate colder water conditions during times of elevated Braarudosphaera deposition. Upwelling and mid-ocean overturn of cold, nutrient-rich, low-salinity water are suggested to be the most likely palaeoceanographic mechanisms for the deposition of Braarudosphaera layers.completedStratigraphyalgaeAtlantic OceanBraarudosphaeraC-13/C-12carbonCenozoicCoccolithophoraceaeDeep Sea Drilling ProjectDSDP Site 363DSDP Site 522IPODisotope ratiosisotopesLeg 40Leg 73microfossilsnannofossilsO-18/O-16Oligoceneoxygenpaleo-oceanographypaleoecologypaleoenvironmentPaleogenepaleotemperaturePlantaequantitative analysisSouth Atlanticstable isotopesTertiaryupwellingurn:org.iodp:exp:40urnlargerWorkCitationcampaignurn:org.iodp:exp:73urnlargerWorkCitationcampaignurn:org.iodp:exp:40:site:363urnlargerWorkCitationstudyurn:org.iodp:exp:40urnlargerWorkCitationcampaignurn:org.iodp:exp:73:site:522urnlargerWorkCitationstudyurn:org.iodp:exp:73urnlargerWorkCitationcampaignEnglishgeoscientificInformation-80.000020.0000-60.000075.0000Atlantic Ocean