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| Titel |
Construction of reliable radiocarbon-based chronologies for speleothems |
| VerfasserIn |
Franziska Lechleitner, Jens Fohlmeister, Cameron McIntyre, Lisa M. Baldini, Robert A. Jamieson, Helena Hercman, Michal Gasiorowski, Jacek Pawlak, Krzysztof Stefaniak, Paweł Socha, Timothy I. Eglinton, James U. L. Baldini |
| 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 |
250131728
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| Publikation (Nr.) |
 EGU/EGU2016-12165.pdf |
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| Zusammenfassung |
| Speleothems have become one of the most widely applied archives for paleoclimate research.
One of their key advantages is their amenability for U-series dating, often producing excellent
high precision chronologies. However, stalagmites with high detrital Th or very low U
concentrations are problematic to date using U-series, and sometimes need to be discarded
from further paleoclimate analysis. Radiocarbon chronologies could present an alternative for
stalagmites that cannot be dated using U-series, if offsets from the “dead carbon
fraction” (DCF) can be resolved. The DCF is a variable reservoir effect introduced
by the addition of 14C-dead carbon from host rock dissolution and soil organic
matter. We present a novel age modeling technique that provides accurate 14C-based
chronologies for stalagmites. As this technique focuses on the long-term decay pattern of
14C, it is only applicable on stalagmites that show no secular variability in their
14C-depth profiles, but is independent of short-term DCF variations. In order to
determine whether a stalagmite is suitable for this method without direct knowledge of
long-term trends in the DCF, we highlight how other geochemical proxies (δ13C,
Mg/Ca) can provide additional information on changes in karst hydrology, soil
conditions, and climate that would affect DCF. We apply our model on a previously
published U-Th dated stalagmite 14C dataset from Heshang Cave, China with excellent
results, followed by a previously ‘undateable’ stalagmite from southern Poland. |
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