Norwegian corals: radiocarbon and stable isotopes in Lophelia pertusa |
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Authors: | NAJA MIKKELSEN HELMUT ERLENKEUSER JOHN S KILLINGLEY WOLFGANG H BERGER |
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Institution: | Naja Mikkelsen, Geological Survey of Denmark, Thoravej 31, DK-2400 Copenhagen NV, Denmark;Helmut Erlenkeuser, Physikalisches Institut der Universität Kiel, Olshausenstr. 40–60, D-2300 Kiel, Germany;John S. Killingley and Wolfgang H. Berger, Scripps Institution of Oceanography, La Jola, 92093 California, U.S.A. |
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Abstract: | The ahermatypic coral Lophelia pertusa which produces aragonitic skeletons is widely distributed along the Norwegian coast. Specimens from a number of localities have been analyzed for oxygen and stable carbon isotope composition and 14C age. Stable isotope ratios of recent corals provide information on growth rate and seasonality of oceanographic conditions. Lophelia can be useful in paleoenvironmental reconstructions. 14C dates of fossil Lophelia from Drøak in the Oslofjord, collected from 20 m ahove and 40 m below present day sea-level, indicate regional extinction between 8700 and 7800 years ago. We suggest that the extinction resulted from the cut-off of deep waters by a rising sill in connection with the postglacial shoreline displacement. Radiocarbon dating of coral bushes suggests a fairly rapid growth rate as older and younger parts of recent corals do not reveal any difference in activity despite the short time scale of the history of bomb-produced 14C in the oceans. |
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