HR: 1330h
AN: PP12A-0230    [PDF]
TI: Extending a Pacific Warm Pool SST Record From the Ontong Java Plateau to 1.0 Ma
AU: * Medina, M A
EM: martinmedina@umail.ucsb.edu
AF: University of California, Department of Geological Sciences, Santa Barbara, CA 93016
AU: Lea, D W
EM: lea@geol.ucsb.edu
AF: University of California, Department of Geological Sciences, Santa Barbara, CA 93016
AU: Spero, H J
EM: spero@geology.ucdavis.edu
AF: University of California, Department of Geology, Davis, CA 95616
AB: Mg/Ca data from planktonic foraminifera in the equatorial Pacific sediment cores demonstrated that tropical Pacific sea surface temperatures (SSTs) were about 3 deg C colder than modern conditions during glacial episodes of the last 500 thousand years (ky)(Lea et al., 2000). We have extended the Globigerinoides ruber Mg/Ca and O18 record from the Western Equatorial Pacific Ocean Drilling Program Hole 806B (0deg19.1'N, 159deg21.7'E, 2520m), back to 15 mbsf, about 700ky BP. Shell samples were cleaned and analyzed using the standard UCSB protocol. For temperature conversion we used a G. ruber calibration based on core-tops from the tropical Pacific (Lea et al., 2000; Dekens et al.,2002). The potential bias on temperature estimates due to the influence of changing preservation over this time interval is estimated at 0.8 §C or less. The record shows that the previously observed 3 deg C-colder SSTs than modern conditions during glacial episodes applies also for MIS 12, 14 and 16. Glacial-interglacial temperature differences as great as 4 deg C are observed between 500 - 800 ky. Point to point comparison between the SST and the O18 records suggests that Mg/Ca-based temperatures consistently lead over O18 by about several ky, as previously observed by Lea et al. (2000). Time-series analysis will be used to confirm these results. By combining the Mg/Ca-based SST estimates with measured O18, we calculated O18w. The average glacial-interglacial O18w amplitude is approximately 0.8 per mil, similar to the estimated value of 0.7 % for the last 500ky (Lea et al., 2000). We aim to extend this record to 1.0 Ma to determine if the pattern and amplitude of SST variability changes during the transition from 40 to 100 ky world.
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
DE: 4870 Stable isotopes
DE: 4875 Trace elements
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting