HR: 10:35h
AN: PP52B-02 INVITED     [Abstracts]
TI: Constraints on Paleocene and Eocene Tropical Sea-Surface Temperatures and Meridional Temperature Gradients From Mg/Ca and Oxygen Isotope Ratios of Foraminifera in Sediments Recovered by the Ocean Drilling Program
AU: * Tripati, A
EM: atri02@esc.cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ United Kingdom
AU: Elderfield, H
EM: he101@esc.cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ United Kingdom
AU: Wade, B
EM: bwade@rci.rutgers.edu
AF: Department of Geological Sciences, Rutgers University, Wright Laboratories , Piscataway, NJ 08854 United States
AU: Kelly, D C
EM: ckelly@geology.wisc.edu
AF: Department of Geology & Geophysics, University of Wisconsin, 1215 W. Dayton Street, Weeks Hall, Madison, WI 53706 United States
AU: Anderson, L D
EM: linda@ucsc.edu
AF: Institute of Marine Sciences, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Sindrey, C
EM: crjs@esc.cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ United Kingdom
AB: Accurate reconstructions of tropical sea surface temperatures (SST) during the Paleocene and Eocene are needed to understand the contribution of greenhouse gases to past climate variability. When combined with constraints on high-latitude SST, tropical SST can be used to estimate past meridional temperature gradients. The traditional tool applied to reconstructing surface temperatures utilizes the temperature-dependant incorporation of oxygen isotopes into calcium carbonate. However, changes in the oxygen isotope composition of foraminiferal calcite also record variations in the isotopic composition of seawater, complicating temperature reconstructions. The magnesium to calcium (Mg/Ca) ratio of foraminiferal carbonate provides an alternative method for reconstructing temperatures in the past that is insensitive to variations in the oxygen isotopic composition of seawater. Here, we present constraints on tropical temperatures from Mg/Ca ratios of planktonic foraminifera in cores recovered by the Ocean Drilling Program during intervals characterized by large changes in atmospheric carbon dioxide levels, including the Paleocene-Eocene Thermal Maximum and the middle to late Eocene "greenhouse-icehouse" transition. Records are for mixed-layer dwellers belonging to the genus Morozovella and Acaranina, and for the thermocline dwelling taxa Subbotina. We combine these results with constraints on high-latitude SST from other proxies, including foraminiferal Mg/Ca and oxygen isotope ratios, to reconstruct changes in the pole-to-equator temperature gradient during these major climate transitions.
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005