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| Titel |
Application of LA-MC-ICP-MS for analysis of Sr isotope ratios in speleothems |
| VerfasserIn |
Michael Weber, Denis Scholz, Jasper A. Wassenburg, Klaus Peter Jochum, Sebastian Breitenbach |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250148049
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| Publikation (Nr.) |
 EGU/EGU2017-12278.pdf |
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| Zusammenfassung |
| Speleothems are well established climate archives. In order to reconstruct past climate
variability, several geochemical proxies, such as δ13C and δ18O as well as trace elements are
available. Since several factors influence each individual proxy, robust interpretation is often
hampered. This calls for multi-proxy approaches involving additional isotope systems that
can help to delineate the role of different sources of water within the epikarst and changes in
soil composition. Sr isotope ratios (87Sr/86Sr) have been shown to provide useful information
about water residence time and water mixing in the host rock. Furthermore, Sr isotopes are
not fractionated during calcite precipitation, implying that the 87Sr/86Sr ratio of
the speleothem provides a direct record of the drip water. While most speleothem
studies applying Sr isotopes used the TIMS methodology, LA-MC-ICP-MS has
been utilized for several other archives, such as otoliths and teeth. This method
provides the advantage of faster data acquisition, higher spatial resolution, larger
sample throughput and the absence of chemical treatment prior to analysis. Here we
present the first LA-MC-ICP-MS Sr isotope data for speleothems. The analytical
uncertainty of our LA-MC-ICP-MS Sr data is in a similar range as for other carbonate
materials. The results of different ablation techniques (i.e. line scan and spots) are
reproducible within error, implying that the application of this technique on speleothems is
possible. In addition, several comparative measurements of different carbonate
reference materials (i.e. MACS-3, JCt-1, JCp-1), such as tests with standard bracketing
and comparison of the 87Sr/86Sr ratios with nanosecond laser ablation system and
a state-of-the-art femtosecond laser ablation system, show the robustness of the
method. We applied the method to samples from Morocco (Grotte de Piste) and India
(Mawmluh Cave). Our results show only very small changes in the 87Sr/86Sr ratios of
both speleothems. However, one speleothem from Mawmluh Cave shows a slight
increase of 87Sr/86Sr within the error, which is reproducible with line scans and spots. |
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