IS THE STABLE ISOTOPE COMPOSITION OF COCCOLITH CARBONATE AN EFFECTIVE PALEOCEANOGRAPHIC PROXY?
P. Ziveri (1), Stoll H. (2), Probert I. (3), Klass C. (4), Ganssen G. (1)
1 Faculty of Earth Sciences, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
2 Geology Dept., Univ. of Oviedo, Spain
3 Laboratoire de Biologie et Biotechnologies Marines, Universite de Caen Basse Normandie, Caen, France
4 Geologisches Institut, ETH-Zentrum, 8092 Zürich, Switzerland
Coccolithophores are an important component of the marine phytoplankton and a major contributors to the carbonate in deep-sea sediments. As phytoplankton their stable isotope composition can provide a sensitive tool for the understanding and reconstruction of the dynamic of the photic zone processes. We use several approaches to investigate the origin of species-dependent non-equilibrium fractionation to evaluate the potential utility of stable isotopes in coccolith calcite for paleoceanographic and paleoclimatologic studies. In culture experiments with several species of Coccolithophorids, we test the dependency of the stable isotope fractionation on coccolithophorid species growth and calcification. In time series sediment traps and core top sediment samples from the Somali Basin, we compared the stable isotope composition of coccoliths (CaCO3, fraction <32micrometer) with that of three species of planktic foraminifera. We will also discuss preliminary results of stable isotope composition of monospecific coccolith assemblage from the Somali trap and sediment samples and the new technique developed for separation of ~monospecific coccolith assemblages from sediments.
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