HR: 1340h
AN: OS33B-1264    [Abstracts]
TI: High-Resolution Tropical Atlantic Climate Variability During Interstadial-12 From the Cariaco Basin
AU: * Black, D E
EM: David.Black@stonybrook.edu
AF: Stony Brook University, School of Marine and Atmospheric Sciences, Stony Brook, NY 11794, United States
AU: Thunell, R C
EM: thunell@geol.sc.edu
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208, United States
AU: Peterson, L C
EM: lpeterson@rsmas.miami.edu
AF: University of Miami, Rosenstiel School of Marine and Atmospheric Science, Miami, FL 33149, United States
AU: Lea, D
EM: lea@geol.ucsb.edu
AF: University of California - Santa Barbara, Department of Earth Sciences, Santa Barbara, CA 93106, United States
AB: Few records from the tropical Atlantic have the ability to resolve climate fluctuations at subdecadal-scale resolution for just the last one thousand years, much less for times further into the past. The high-deposition rate sediments of the Cariaco Basin make it one of the premier archives of high-resolution tropical Atlantic variability. Here we present data with subdecadal-scale resolution from piston core sediments deposited during the latter part of Interstadial-12 (IS-12). Core MD03-2622 was sampled at consecutive one-millimeter intervals resulting in an average temporal resolution of approximately 2 years per sample based on correlations between sediment reflectivity and the Greenland Ice Core 2 stable oxygen isotope record. The foraminifer population is distinctly different from the modern assemblage. The tropical upwelling foraminifer Globigerina bulloides still dominates the total assemblage, but the relative abundance of other major taxa differ significantly from the modern. Orbulina universa is the second-most common species in the modern assemblage, but is nearly non-existent during the end of IS-12, and the average size of individual specimens is much smaller than those from today. Instead, Neogloboquadrina dutertrei (and P-D intergrade) is (are) the second most abundant taxa. In some ways, the Cariaco Basin foraminiferal assemblage during IS-12 resembles that of the modern Santa Barbara Basin assemblage, including the presence of Globigerina quinqueloba. Spectral analysis of the IS-12 G. bulloides abundance data reveals peaks at 8-10 yrs, 12.5-13.0 yrs, 16 yrs, 21 yrs, 32 yrs, and 140-500 yrs. Not only do we observe periodicities similar to those found under modern conditions during late-IS-12 (the decadal- and centennial-scale modes), we also see a pronounced interdecadal mode that is completely absent in the modern record. Additionally, the relative amplitudes of the 8-10 yrs and 12.5-13.0 yrs peaks are reduced compared to power in the interdecadal band. This apparent change in the behavior of the trade wind/ITCZ system is likely related to changes in the cross-equatorial sea surface temperature gradient.
DE: 0459 Macro- and micropaleontology (3030, 4944)
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 4964 Upwelling (4279)
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting