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| Titel |
Identifying vital effects in Halimeda algae with Ca isotopes |
| VerfasserIn |
C. L. Blättler, S. M. Stanley  , G. M. Henderson, Hugh C. Jenkyns |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 24 ; Nr. 11, no. 24 (2014-12-17), S.7207-7217 |
| Datensatznummer |
250117744
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| Publikation (Nr.) |
 copernicus.org/bg-11-7207-2014.pdf |
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| Zusammenfassung |
| Geochemical records of biogenic carbonates provide some of the most
valuable records of the geological past, but are often difficult to
interpret without a mechanistic understanding of growth
processes. In this experimental study, Halimeda algae are
used as a test organism to untangle some of the specific factors
that influence their skeletal composition, in particular their
Ca-isotope composition. Algae were stimulated to precipitate both
calcite and aragonite by growth in artificial Cretaceous
seawater, resulting in experimental samples with somewhat malformed
skeletons. The Ca-isotope fractionation of the algal calcite (−0.6‰)
appears to be much smaller than that for the algal aragonite (−1.4‰),
similar to the behaviour
observed in inorganic precipitates. However, the carbonate from
Halimeda has higher Ca-isotope ratios than inorganic forms by
approximately 0.25‰,
likely because of Rayleigh distillation within the algal intercellular
space. In identifying specific vital effects and the magnitude of
their influence on Ca-isotope ratios, this study suggests that
mineralogy has a first-order control on the marine Ca-isotope cycle. |
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