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UBC Theses and Dissertations
Productivity influences on oxygenation of the Santa Barbara Basin, California, during the late Quaternary Ivanochko, Tara S.
Abstract
Short-term fluctuations in the bottom water oxygen content of Santa Barbara Basin have been previously recognized from variations in a sedimentary bioturbation index (Behl and Kennett, 1996). A correlation between such anoxic events in the basin and Dansgaard-Oeschger interstadials, as measured from δ180ice in Greenland ice cores, was then used by the same authors to relate variations in bottom water oxygenation to high-frequency changes in the ventilation of the Santa Barbara Basin, driven by pan-hemispheric changes in climate transmitted through the atmosphere. An additional control on the oxygen content at depth is the local settling flux of metabolizable organic matter. Trace metal measurements from closely-spaced sediment samples are used here to distinguish oxygen depletion resulting from local increases in export production from oxygen depletion introduced by the importation of O2-poor water. Molybdenum, Re, U, Cd, and Ag and interelement ratios are used in conjunction with organic carbon concentrations, opal fluxes, and δ15N measurements to deduce into past redox conditions of the basin, variations in the depth of the redox boundary and the flux of organic material to the basin floor. Comparisons between ODP Holes 893A (Santa Barbara Basin), 1019 and 1017 (both California margin) allows one to distinguish of regional signals dominated by ventilation changes from local signals dominated by vertical organic flux. During the Holocene, variations in productivity appear indeed to have impacted the oxygen content of the Santa Barbara Basin bottom waters. However, anoxic events concurrent with the Bolling-Allerod and during the last glacial interval are regional events associated with intermediate water mass characteristics.
Item Metadata
Title |
Productivity influences on oxygenation of the Santa Barbara Basin, California, during the late Quaternary
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2001
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Description |
Short-term fluctuations in the bottom water oxygen content of Santa Barbara
Basin have been previously recognized from variations in a sedimentary bioturbation
index (Behl and Kennett, 1996). A correlation between such anoxic events in the
basin and Dansgaard-Oeschger interstadials, as measured from δ180ice in Greenland
ice cores, was then used by the same authors to relate variations in bottom water
oxygenation to high-frequency changes in the ventilation of the Santa Barbara
Basin, driven by pan-hemispheric changes in climate transmitted through the
atmosphere. An additional control on the oxygen content at depth is the local settling
flux of metabolizable organic matter. Trace metal measurements from closely-spaced
sediment samples are used here to distinguish oxygen depletion resulting
from local increases in export production from oxygen depletion introduced by the
importation of O2-poor water. Molybdenum, Re, U, Cd, and Ag and interelement
ratios are used in conjunction with organic carbon concentrations, opal fluxes, and
δ15N measurements to deduce into past redox conditions of the basin, variations in
the depth of the redox boundary and the flux of organic material to the basin floor.
Comparisons between ODP Holes 893A (Santa Barbara Basin), 1019 and 1017
(both California margin) allows one to distinguish of regional signals dominated by
ventilation changes from local signals dominated by vertical organic flux. During the
Holocene, variations in productivity appear indeed to have impacted the oxygen
content of the Santa Barbara Basin bottom waters. However, anoxic events
concurrent with the Bolling-Allerod and during the last glacial interval are regional
events associated with intermediate water mass characteristics.
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Extent |
6435917 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-08-05
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0052541
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2001-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
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Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.