georefid:2010-093053SEDIS 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=2010-0930532009-01-01publicationgeorefid:2010-093053Kumar Rai, AjaiUniversity of Allahabad, Department of Earth and Planetary Sciences, Allahabad, IndiaauthorSingh Maurya, AbhayanandauthorCouncil of Scientific & Industrial Research, New Delhi, IndiapublisherdocumentHardcopyIndian Journal of Marine Sciences38 (4)423-431Miocene deep sea benthic foraminiferal diversity at ODP site 754A, in the southeastern Indian Ocean was examined in the present study. Paleoceanographic and palcoclimatic changes were inferred based on the above study. Species diversity was measured in terms of Shannon-Weaver Index [H(S)], Hurlbert's Diversity Index (S (sub 100) ), Alpha Index (alpha ) and Equitability (E'). Values of S (sub 100) show more positive correlation with H(S) and a value. All diversity parameters show almost similar pattern during the study interval. Present study infers that the changing trophic level has much influence on the faunal diversity. More diverse fauna of late early Miocene to early middle Miocene along with low delta (super 18) O and high delta (super 13) C values reflect warm and stable bottom waters with low food supply. This corresponds to the Miocene climatic optimum. This was also an interval of global warming and reduced Antarctic ice-sheet volume. Significant decline in diversity and delta (super 13) C values along with abrupt increase in delta (super 18) O values at approximately 14 Ma indicate cold, relatively less oxygenated and unstable bottom waters with increased food supply due to higher surface productivity. Development of thermal gradient between low and high latitudes in response to the expansion of Antarctic ice-sheet during 15-12.5 Ma was responsible for increased upwelling and high surface productivity. Decrease in faunal diversity at approximately 7 Ma onwards along with low delta (super 13) C and high delta (super 18) O values corresponds with the Chron-6 negative Carbon shift, expansion of west Antarctic ice-sheets and lowering of sea level.completedStratigraphyIsotope geochemistryassemblagesbenthic environmentbenthic taxabiochemistryBroken RidgeC-13/C-12carbonCenozoicForaminiferageochemistryIndian OceanInvertebrataisotope ratiosisotopesLeg 121microfossilsMioceneNeogeneO-18/O-16Ocean Drilling ProgramODP Site 754oxygenpaleo-oceanographypaleoclimatologypaleoecologypaleoenvironmentProtistasea-level changesspecies diversitystable isotopesTertiaryurn:org.iodp:exp:121urnlargerWorkCitationcampaignurn:org.iodp:exp:121:site:754urnlargerWorkCitationstudyurn:org.iodp:exp:121urnlargerWorkCitationcampaignEnglishgeoscientificInformation93.335793.3400-30.5627-30.5627