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Thorium-230 normalized particle flux and sediment focusing in the Panama Basin region during the last 30,000 years Calvert, Stephen E.; Francois, Roger

Abstract

Application of the 230Th normalization method to estimate sediment burial fluxes in six cores from the eastern equatorial Pacific (EEP) reveals that bulk sediment and organic carbon fluxes display a coherent regional pattern during the Holocene that is consistent with modern oceanographic conditions, in contrast with estimates of bulk mass accumulation rates (MARs) derived from core chronologies. Two nearby sites (less than 10 km apart), which have different MARs, show nearly identical 230Th-normalized bulk fluxes. Focusing factors derived from the 230Th data at the foot of the Carnegie Ridge in the Panama Basin are >2 in the Holocene, implying that lateral sediment addition is significant in this part of the basin. New geochemical data and existing literature provide evidence for a hydrothermal source of sediment in the southern part of the Panama Basin and for downslope transport from the top of the Carnegie Ridge. The compilation of core records suggests that sediment focusing is spatially and temporally variable in the EEP. During oxygen isotope stage 2 (OIS 2, from 13–27 ka BP), focusing appears even higher compared to the Holocene at most sites, similar to earlier findings in the eastern and central equatorial Pacific. The magnitude of the glacial increase in focusing factors, however, is strongly dependent on the accuracy of age models. We offer two possible explanations for the increase in glacial focusing compared to the Holocene. The first one is that the apparent increase in lateral sediment redistribution is partly or even largely an artifact of insufficient age control in the EEP, while the second explanation, which assumes that the observed increase is real, involves enhanced deep sea tidal current flow during periods of low sea level stand. An edited version of this paper was published by AGU. Copyright 2007 American Geophysical Union.

Item Metadata

Title
Thorium-230 normalized particle flux and sediment focusing in the Panama Basin region during the last 30,000 years
Creator
Calvert, Stephen E.; Francois, Roger
Contributor
University of British Columbia. Pacific Centre for Isotopic and Geochemical Research
Publisher
American Geophysical Union
Date Issued
2007
Description
Application of the 230Th normalization method to estimate sediment burial fluxes in six cores from the eastern equatorial Pacific (EEP) reveals that bulk sediment and organic carbon fluxes display a coherent regional pattern during the Holocene that is consistent with modern oceanographic conditions, in contrast with estimates of bulk mass accumulation rates (MARs) derived from core chronologies. Two nearby sites (less than 10 km apart), which have different MARs, show nearly identical 230Th-normalized bulk fluxes. Focusing factors derived from the 230Th data at the foot of the Carnegie Ridge in the Panama Basin are >2 in the Holocene, implying that lateral sediment addition is significant in this part of the basin. New geochemical data and existing literature provide evidence for a hydrothermal source of sediment in the southern part of the Panama Basin and for downslope transport from the top of the Carnegie Ridge. The compilation of core records suggests that sediment focusing is spatially and temporally variable in the EEP. During oxygen isotope stage 2 (OIS 2, from 13–27 ka BP), focusing appears even higher compared to the Holocene at most sites, similar to earlier findings in the eastern and central equatorial Pacific. The magnitude of the glacial increase in focusing factors, however, is strongly dependent on the accuracy of age models. We offer two possible explanations for the increase in glacial focusing compared to the Holocene. The first one is that the apparent increase in lateral sediment redistribution is partly or even largely an artifact of insufficient age control in the EEP, while the second explanation, which assumes that the observed increase is real, involves enhanced deep sea tidal current flow during periods of low sea level stand. An edited version of this paper was published by AGU. Copyright 2007 American Geophysical Union.
Subject
Low-temperature Geochemistry
Genre
Article
Type
Text
Language
eng
Date Available
2017-01-11
Provider
Vancouver : University of British Columbia Library
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International
DOI
10.14288/1.0103619
URI
http://hdl.handle.net/2429/40059
Affiliation
Science, Faculty of; Earth and Ocean Sciences, Department of
Citation
Kienast, Stephanie S.; Kienast, Markus; Mix, Alan C.; Calvert, Stephen E.; Francois, Roger. 2007. Thorium-230 normalized particle flux and sediment focusing in the Panama Basin region during the last 30,000 years. Paleoceanography, 22(2) PA2213.
Publisher DOI
10.1029/2006PA001357
Peer Review Status
Reviewed
Scholarly Level
Faculty
Copyright Holder
Francois, Roger
Rights URI
http://creativecommons.org/licenses/by-nc-nd/4.0/
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Attribution-NonCommercial-NoDerivatives 4.0 International