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| Titel |
Determination of aragonite trace element partition coefficients from
speleothem calcite-aragonite transitions |
| VerfasserIn |
Jasper A. Wassenburg, Denis Scholz, Klaus Peter Jochum, Hai Cheng, Jessica Oster, Adrian Immenhauser, Detlev K. Richter, Tobias Haeger, Dirk Hoffmann, Sebastian F. M. Breitenbach |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250134803
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| Publikation (Nr.) |
 EGU/EGU2016-15569.pdf |
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| Zusammenfassung |
| Speleothem trace element variability has often been linked to environmental changes.
While research has focused on element incorporation into speleothem calcite, our
current knowledge of trace element variability in speleothem aragonite is limited to a
few studies only. Here we present, to our knowledge, for the first time quantitative
estimates of distribution coefficients for speleothem aragonite (DMg, DBa, DSr,
and DU). These were derived from ten calcite-to-aragonite transitions from seven
speleothems from Morocco, Germany, Spain, France and India. Our calculations
indicate the following distribution coefficients: DMg = 1.01E-04 ± 9.0E-05,
DBa(Ar) = 0.91 ± 0.53, DSr(Ar) = 1.38 ± 0.53, and DU(Ar) = 6.26 ± 4.53.
These results are discussed in the context of speleothem growth rates, Rayleigh
distillation effects, temperature, drip water elemental composition and drip water
pH.
We conclude that speleothem aragonite DMg(Ar) is below one, DSr(Ar) is close to unity,
and DU(Ar) is above one. For DBa(Ar), such a conclusion is difficult. Speleothem growth rate
may affect aragonite DSr in samples forming at a growth rate lower than 20 μm/a. Our results
also indicate that calcite DSr and calcite DBa are affected by the Mg content of calcite. This
has important implications for studies attempting to quantify processes like prior
calcite precipitation. In particular, DSr and DBa cannot be transferred from caves
developed within a limestone host rock to caves developed within a dolostone host rock. |
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