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2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 251-12
Presentation Time: 4:50 PM

OXYGEN ISOTOPIC VARIATIONS IN MODERN CETACEAN TEETH AND BONES: IMPLICATIONS FOR PALEOECOLOGICAL, PALEOCLIMATIC AND PALEOCEANOGRAPHIC STUDIES


CINER, Burcu, Department of Earth, Ocean and Atmospheric Science, Florida State University, National High Magnetic Field Laboratory, Tallahassee, FL 32304; Geological Engineering, Balikesir University, Balikesir, 10460, Turkey, WANG, Yang, Earth, Ocean and Atmospheric Science, Florida State University, 909 Antarctica Way, PO Box 3064100, Tallahassee, FL 32306-4100; Geochemistry Program, National High Magnetic Field Laboratory, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310 and PARKER, William, Earth, Ocean, and Atmospheric Science, Florida State University, 909 Antarctic Way, P.O. Box 3064100, Tallahassee, FL 32306-4100, ywang@magnet.fsu.edu

The oxygen isotope ratios (δ18O) preserved in marine sediments have been widely used to reconstruct past ocean temperatures. However, there remain significant uncertainties associated with this method, owing to assumptions about the δ18O of ancient seawater which affects the temperature inferred from sediment δ18O records. In this study, oxygen isotope compositions of phosphate in teeth and bones from a diverse group of modern cetaceans, including sperm whale, pygmy sperm whale, short-finned pilot whale, killer whale and Cuvier’s beaked whale, and three fossil whales were determined. The data were used to assess if the oxygen isotope ratios of biogenic phosphate (δ18Op) from cetaceans are a reliable proxy for the oxygen isotopic composition of ocean water (δ18Ow). The δ18Op values of modern cetaceans range from 15.5‰ to 21.3‰, averaging 19.6±0.8‰ (n=136). Using a greatly expanded global cetacean δ18Opdataset, the following regression equation is derived for cetaceans:

δ 18Ow = 0.95317(+0.03293) δ 18Op – 17.971(+0.605), r= 0.97253.

The new equation, when applied to fossil cetacean teeth and bones, yielded reasonable estimates of ancient seawater δ18Ow values. Intra-tooth oxygen isotopic variations within a whale tooth record changes in the isotopic composition of environmental water during the time of tooth growth, providing insights into the life history or migratory behavior of the whale. The results from this study demonstrated the potential of using oxygen isotopes in the phosphate component of cetacean teeth and bones to examine the migratory behaviors and environmental preferences of both modern and ancient whales and to track past changes in ocean water oxygen isotopic composition.

Session No. 251

T154. Phanerozoic Evolution in the Oceans: Effects of Warming and Chemical Changes
Tuesday, 3 November 2015: 1:30 PM-5:30 PM
Room 316 (Baltimore Convention Center)
Geological Society of America Abstracts with Programs. Vol. 47, No. 7, p.641
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