Oxygen isotope composition of the final chamber of planktic foraminifera provides evidence of vertical migration and depth-integrated growth
Résumé
The translation of the original seawater signal (i.e. ambient temperature and δ 18 O sw) into distinct chambers of a single shell of a foraminifer during calcification can influence our interpretation of surface ocean conditions of the past, when based upon oxygen and carbon stable isotope geochemistry. In this study three different hypotheses were tested to gain more insight into biological and ecological processes that influence the resultant composition of stable isotopes of oxygen (δ 18 O) in the shells of planktonic foraminifera. These hypotheses were related to the shell size; the differences in isotopic composition between the final chamber and the remaining shell; and the differences between different species. Shells of Trilobatus sacculifer, Globigerinoides ruber white and Neogloboquad-rina dutertrei were picked from the top of multi-core GS07-150-24, of modern age, offshore of northeastern Brazil (3 • 46.474 S, 37 • 03.849 W) and analysed for single-shell and single-chamber stable isotope analysis. We show that the mean value of δ 18 O of the final chambers (δ 18 O F) is 0.2 ‰ ± 0.4 ‰ (1σ) higher than the mean value δ 18 O of the test minus the final chamber (δ 18 O
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https://hal.science/hal-02974728
Soumis le : lundi 26 octobre 2020-19:48:53
Dernière modification le : mercredi 15 mai 2024-13:24:25
Archivage à long terme le : mercredi 27 janvier 2021-19:30:30
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Hilde Pracht, Brett Metcalfe, Frank Peeters. Oxygen isotope composition of the final chamber of planktic foraminifera provides evidence of vertical migration and depth-integrated growth. Biogeosciences, 2019, 16 (2), pp.643-661. ⟨10.5194/bg-16-643-2019⟩. ⟨hal-02974728⟩
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