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PALEOCEANOGRAPHY, VOL. 18, NO. 2, 1024, doi:10.1029/2002PA000798, 2003

Early Cenozoic benthic foraminiferal isotopes: Species reliability and interspecies correction factors

Miriam E. Katz

Department of Geological Sciences, Rutgers University, Piscataway, New Jersey, USA


David R. Katz

NumberWise Consulting, Hermon, New York, USA


James D. Wright

Department of Geological Sciences, Rutgers University, Piscataway, New Jersey, USA


Kenneth G. Miller

Department of Geological Sciences, Rutgers University, Piscataway, New Jersey, USA
Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA


Dorothy K. Pak

Department of Geological Sciences, Marine Science Institute, University of California, Santa Barbara, California, USA


Nicholas J. Shackleton

Godwin Laboratory, University of Cambridge, Cambridge, UK


Ellen Thomas

Department of Earth and Environmental Science, Wesleyan University, Middletown, Connecticut, USA
Department of Geology and Geophysics, Yale University, New Haven, Connecticut, USA


Abstract

Oxygen and carbon isotope records are important tools used to reconstruct past ocean and climate conditions, with those of benthic foraminifera providing information on the deep oceans. Reconstructions are complicated by interspecies isotopic offsets that result from microhabitat preferences (carbonate precipitation in isotopically distinct environments) and vital effects (species-specific metabolic variation in isotopic fractionation). We provide correction factors for early Cenozoic benthic foraminifera commonly used for isotopic measurements (Cibicidoides spp., Nuttallides truempyi, Oridorsalis spp., Stensioina beccariiformis, Hanzawaia ammophila, and Bulimina spp.), showing that most yield reliable isotopic proxies of environmental change. The statistical methods and larger data sets used in this study provide more robust correction factors than do previous studies. Interspecies isotopic offsets appear to have changed through the Cenozoic, either (1) as a result of evolutionary changes or (2) as an artifact of different statistical methods and data set sizes used to determine the offsets in different studies. Regardless of the reason, the assumption that isotopic offsets have remained constant through the Cenozoic has introduced an ∼1–2°C uncertainty into deep sea paleotemperature calculations. In addition, we compare multiple species isotopic data from a western North Atlantic section that includes the Paleocene-Eocene thermal maximum to determine the most reliable isotopic indicator for this event. We propose that Oridorsalis spp. was the most reliable deepwater isotopic recorder at this location because it was best able to withstand the harsh water conditions that existed at this time; it may be the best recorder at other locations and for other extreme events also.

Published 9 April 2003.

Index Terms: 3030 Marine Geology and Geophysics: Micropaleontology; 4267 Oceanography: General: Paleoceanography; 4804 Oceanography: Biological and Chemical: Benthic processes/benthos; 4870 Oceanography: Biological and Chemical: Stable isotopes.

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Citation: Katz, M. E., D. R. Katz, J. D. Wright, K. G. Miller, D. K. Pak, N. J. Shackleton, and E. Thomas (2003), Early Cenozoic benthic foraminiferal isotopes: Species reliability and interspecies correction factors, Paleoceanography, 18(2), 1024, doi:10.1029/2002PA000798.