georefid:2011-000770SEDIS 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=2011-0007702010-01-01publicationgeorefid:2011-000770Singh, Raj K.Indian Institute of Technology, Department of Geology and Geophysics, Kharagpur, IndiaauthorGupta, Anil K.authorInternational Union of Geological Sciences (IUGS), Ottawa, ON, CanadapublisherdocumentHardcopyEpisodes33 (2)74-82This study analyses 26.5 Ma record of deep-sea benthic foraminifera from 194 samples from Ocean Drilling Program Hole 757B (latitude 17 degrees 01.458' S, longitude 88 degrees 10.899' E, water depth of 1652.1m) located on the Ninetyeast Ridge, southeastern Indian Ocean below equatorial divergence zone. The data document important changes in benthic foraminiferal population at Hole 757B since the late Oligocene. The well-oxygenated, oligotropic species including Cibicides cicartricosus, C. pseudoungerianus and Oridorsalis umbonatus were dominant during the late Oligocene to the early Miocene. These species began to decline as site 757 moved northward into the influence of the Indonesian Throughflow (ITF) beneath surface and subsurface water masses from the Pacific Ocean. Cibicides cicatricosus and C. pseudoungerianus disappeared in the late Miocene (10-8Ma) at Hole 757B. The lower bathyal to abyssal species Nuttallides umbonifera shows a major increase at approximately 11.5 Ma coinciding with a signifcant increase in Neodymium (Nd) isotope values, indicating substantial transport of deep Pacific water to the Indian Ocean through the Indonesian seaway. Nuttallides umbonifera decreases drastically during 3-2.8 Ma, though the Nd isotope values do not show a decrease. We relate this change to a low sample resolution in the latter study. This event coincides with the final closure of the Indonesian seaway and a switch in shallow ITF source from warm, saline South Pacific to cool, fresh North Pacific thermocline water, which triggered global cooling and major expansion of Northern Hemisphere glaciation.completedStratigraphyassemblagesbenthic taxaCenozoicdeep-sea environmentForaminiferaglaciationIndian OceanIndonesian SeawayIndonesian ThroughflowInvertebrataLeg 121marine environmentmicrofossilsNeogeneNinetyeast Ridgeocean circulationOcean Drilling ProgramODP Site 757Oligocenepaleo-oceanographypaleoclimatologypaleoenvironmentPaleogeneProtistaquantitative analysisQuaternaryTertiaryurn:org.iodp:exp:121urnlargerWorkCitationcampaignurn:org.iodp:exp:121:site:757urnlargerWorkCitationstudyurn:org.iodp:exp:121urnlargerWorkCitationcampaignEnglishgeoscientificInformation88.104888.1054-17.0128-17.0123Includes appendix