HR: 09:30h
AN: PP41E-07    [Abstracts]
TI: Deglacial sea surface and deep chlorophyll maximum temperature variations in the eastern equatorial Pacific: implications for regional palaeoceanography
AU: * Mekik, F
EM: mekikf@gvsu.edu
AF: Grand Valey State University, Department of Geology, Allendale, MI 49401, United States
AU: Kienast, M
EM: Markus.Kienast@dal.ca
AF: Dalhousie University, Department of Oceanography, Halifax, NS B3H 4J1, Canada
AU: Kienast, S
EM: stephanie.kienast@dal.ca
AF: Dalhousie University, Department of Oceanography, Halifax, NS B3H 4J1, Canada
AU: Francois, R
EM: rfrancoi@eos.ubc.ca
AF: University of British Columbia, Department of Earth and Ocean Sciences, Vancouver, BC V6T 1Z4, Canada
AU: Loubere, P
EM: paul@geol.niu.edu
AF: Northern Illinois University, Department of Geology and Environmental Geosciences, DeKalb, IL 60115, United States
AU: Mix, A
EM: amix@coas.oregonstate.edu
AF: Oregon State University, College of Oceanic and Atmospheric Science, Corvallis, OR 97331, United States
AB: The eastern equatorial Pacific (EEP) is a major upwelling region in which multiple current systems interact and surface ocean temperatures and productivity strongly vary. We examined two high sedimentation rate cores from the EEP, ME 24J and ME 27J, in order to assess changes in upwelling dynamics there since the Last Glacial Maximum (LGM). We will present temperature estimates from both cores for the sea surface (SST) using Uk37 and the deep chlorophyll maximum (DCM) using Mg/Ca from N. dutertrei which are well known to be DCM dwellers. Because Mg/Ca in planktonic foraminifers is significantly influenced by post-depositional calcite dissolution, we used the Globorotalia menardii fragmentation index and equations developed by Mekik et al. (2007) to correct the Mg/Ca temperature estimates for dissolution. Our results show a strong increase in DCM temperatures with a concurrent drop in SST during the deglacial, while the uncorrected temperature estimates also show a warming during the deglacial but less so than the dissolution corrected estimates. Subsequently, SST rises while dissolution corrected DCM temperatures steadily drop until they reach their present day values (15-18 degrees C). Our new records will be discussed in terms of changes in water column structure, water mass distributions and upwelling dynamics during the last 21 kyrs. We will also revisit various approaches used to correct foraminiferal Mg/Ca records for dissolution. Mekik, F., R. Francois and M. Soon, 2007. A novel approach to dissolution correction of Mg/Ca-based paleothermometry in the tropical Pacific. Paleoceanography, in press.
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4231 Equatorial oceanography
DE: 4964 Upwelling (4279)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting