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Xie, Ruifang C. and Marcantonio, Franco (2012): Deglacial dust provenance changes in the eastern Equatorial Pacific and implications for ITCZ movement
Leg/Site/Hole:
Related Expeditions:
ODP 138
ODP 138 848
ODP 138 849
ODP 138 850
ODP 138 851
ODP 138 852
ODP 138 853
Identifier:
ID:
2012-051995
Type:
georefid
ID:
10.1016/j.epsl.2011.11.014
Type:
doi
Creator:
Name:
Xie, Ruifang C.
Affiliation:
Texas A&M University, Department of Geology and Geophysics, College Station, TX, United States
Role:
author
Name:
Marcantonio, Franco
Affiliation:
Role:
author
Identification:
Title:
Deglacial dust provenance changes in the eastern Equatorial Pacific and implications for ITCZ movement
Year:
2012
Source:
Earth and Planetary Science Letters
Publisher:
Elsevier, Amsterdam, Netherlands
Volume:
317-318
Issue:
Pages:
386-395
Abstract:
The 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.
Language:
English
Genre:
Serial
Rights:
URL:
Coverage:
Geographic coordinates:
North:7.1240
West:-110.3111
East: -109.4504
South:-2.5940
Keywords:
Quaternary geology; Isotope geochemistry; alkaline earth metals; atmospheric circulation; Australasia; Australia; Cenozoic; clastic sediments; deglaciation; dust; East Pacific; Equatorial Pacific; Holocene; intertropical convergence zone; isotopes; lead; Leg 138; marine sediments; metals; neodymium; North Pacific; Northeast Pacific; Ocean Drilling Program; ODP Site 848; ODP Site 849; ODP Site 850; ODP Site 851; ODP Site 852; ODP Site 853; Pacific Ocean; provenance; Quaternary; rare earths; sediment transport; sediments; South Pacific; Southeast Pacific; strontium; temporal distribution; transport; upwelling;
.
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