HR: 0800h
AN: PP11A-0545    [Abstracts]
TI: Changes in Deep Sea Temperature and Ice Volume Based on Paired Measurements of Benthic Foraminiferal Mg/Ca and $\delta$$^{18}$O: Evidence from ODP Site 849, Equatorial Pacific for Marine Isotope Stages 1-3
AU: * Healey, S L
EM: shealey@geol.sc.edu
AF: Department of Geological Sciences, University of South Carolina, 700 Sumter St., Columbia, SC 29208 United States
AU: Thunell, R
EM: thunell@geol.sc.edu
AF: Department of Geological Sciences, University of South Carolina, 700 Sumter St., Columbia, SC 29208 United States
AB: Most continuous records of sea level changes are based on benthic foraminiferal $\delta$$^{18}$O, which is a measure of both the $\delta$$^{18}$O of seawater and temperature. New calibrations [Martin et al., 2002; Lear et al., 2002] between temperature and Mg/Ca ratios in benthic foraminiferal calcite provide a means to differentiate the separate effects of temperature and global ice volume on the benthic foraminiferal $\delta$$^{18}$O signal. We have measured the Mg/Ca ratio of the benthic foraminifera species, {\it Cibicidoides wuellerstorfi}, throughout Marine Isotope Stages (MIS) 1-3 (0-60 Ka) in sediments from Eastern Equatorial Pacific, ODP Site 849 (0$\deg$11'N, 110$\deg$ 31'W; 3851 m). Using published Mg/Ca -temperature relationships for this species, we estimate a 2.5$\deg$C increase in bottom water temperature at this location over Termination 1. The change in benthic foraminiferal $\delta$$^{18}$O associated with this deglaciation is ~1.6$\permil$ [Mix et al., 1995]. Using a conversion factor of 0.23 $\permil$ per 1$\deg$C [Kim and O'Neil, 1997], the $\delta$$^{18}$O change accounted for by a 2.5$\deg$C change in temperature is approximately 0.58$\permil$, suggesting a residual 1.02$\permil$ change to be accounted for by the change in global ice volume over Termination 1. This is consistent with previous estimates of the global $\delta$$^{18}$O change of seawater due to melting of continental ice sheets since the Last Glacial Maximum.
DE: 4825 Geochemistry
DE: 4870 Stable isotopes
DE: 4875 Trace elements
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting