georefid:2012-051995SEDIS 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=10.1016/j.epsl.2011.11.0142012-01-01publicationgeorefid:2012-051995doi:10.1016/j.epsl.2011.11.014Xie, Ruifang C.Texas A&M University, Department of Geology and Geophysics, College Station, TX, United StatesauthorMarcantonio, FrancoauthorElsevier, Amsterdam, NetherlandspublisherdocumentHardcopyEarth and Planetary Science Letters317-318386-395The provenance of eolian dust supplied to deep-sea sediments has the potential to offer insights into changes in past atmospheric circulation. Specifically, measuring temporal changes in dust provenance can shed light on changes in the mean position of the Intertropical Convergence Zone (ITCZ), a region acting as a barrier separating wind-blown material derived from northern versus southern hemisphere sources. Here we have analyzed Nd, Sr, and Pb isotope ratios in the operationally-defined detrital component extracted from deep-sea sediments in the eastern equatorial Pacific (EEP) along a meridional transect at 110 degrees W from 3 degrees S to 7 degrees N (ODP Leg 138, sites 848-853). Sr isotope results show that barite Sr has a significant influence on (super 87) Sr/ (super 86) Sr isotope ratios of samples in the upwelling zone of the EEP. However, sites located >3 degrees or more away from the equator (sites 852 and 853) are believed to not be affected by barite Sr and provide useful detrital Sr signals. (super 208) Pb/ (super 206) Pb and (super 207) Pb/ (super 206) Pb ratios in all cores fall into the Pb-isotope space of five potential dust sources (Asia, North and Central/South America, Sahara, and Australia), with no distinct isotopic fingerprinting of the dominant source(s). epsilon (sub Nd) values were most valuable for discerning detrital source provenance, and their values at all sites, ranging from -5.46 to -3.25, were more unradiogenic for sediments deposited during the last glacial than for those deposited during the Holocene. There are distinct latitudinal trends in the epsilon (sub Nd) values, with more radiogenic values further south and less radiogenic values further north, excluding site 848. This distinction holds true for both Holocene and last glacial periods. For the most southerly site, 848, we invoke, for the first time, a distinct southern hemisphere Australian source as being responsible for the unradiogenic Nd isotope ratios. Both average last glacial and Holocene epsilon (sub Nd) values show similar sharp gradients along the transect between 5.29 degrees N and 2.77 degrees N, suggesting little movement of the glacial ITCZ in the EEP. However, during the deglacial, this gradient is stronger and shifted further north between 5.29 degrees N and 7.21 degrees N, suggesting a more northerly, possibly stronger, deglacial ITCZ. Abstract Copyright (2012) Elsevier, B.V.completedQuaternary geologyIsotope geochemistryalkaline earth metalsatmospheric circulationAustralasiaAustraliaCenozoicclastic sedimentsdeglaciationdustEast PacificEquatorial PacificHoloceneintertropical convergence zoneisotopesleadLeg 138marine sedimentsmetalsneodymiumNorth PacificNortheast PacificOcean Drilling ProgramODP Site 848ODP Site 849ODP Site 850ODP Site 851ODP Site 852ODP Site 853Pacific OceanprovenanceQuaternaryrare earthssediment transportsedimentsSouth PacificSoutheast Pacificstrontiumtemporal distributiontransportupwellingurn:org.iodp:exp:138urnlargerWorkCitationcampaignurn:org.iodp:exp:138:site:848urnlargerWorkCitationstudyurn:org.iodp:exp:138urnlargerWorkCitationcampaignurn:org.iodp:exp:138:site:849urnlargerWorkCitationstudyurn:org.iodp:exp:138urnlargerWorkCitationcampaignurn:org.iodp:exp:138:site:850urnlargerWorkCitationstudyurn:org.iodp:exp:138urnlargerWorkCitationcampaignurn:org.iodp:exp:138:site:851urnlargerWorkCitationstudyurn:org.iodp:exp:138urnlargerWorkCitationcampaignurn:org.iodp:exp:138:site:852urnlargerWorkCitationstudyurn:org.iodp:exp:138urnlargerWorkCitationcampaignurn:org.iodp:exp:138:site:853urnlargerWorkCitationstudyurn:org.iodp:exp:138urnlargerWorkCitationcampaignEnglishgeoscientificInformation-110.3111-109.4504-2.59407.1240Supplementary data available in online version