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| Titel |
Advances in noble gas paleothermometry on speleothems |
| VerfasserIn |
Thomas Marx, Tobias Kluge, Augusto Mangini, Werner Aeschbach-Hertig |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043502
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| Zusammenfassung |
| The application of the noble gas paleothermometer on speleothem fluid inclusions promises
to provide absolute paleotemperatures from stalagmites. These noble gas temperatures
(NGTs) are based on the temperature dependent solubility of gases in water and could help to
interpret other speleothem proxies. In particular NGTs may help to better understand oxygen
isotope records.
In summer and autumn 2009 a measurement run with 26 (sub-)samples from 9 different
caves was performed. The water and the noble gases were released using a stepwise
extraction technique by online in vacuo crushing and thermal heating. Depending on
the sample water amount about three extraction steps were performed for each
sample, so that the total number of speleothem measurements exceeded 80 in this
run.
NGTs were determined from noble gas concentrations by inverse modeling. Only the
equilibrium solubility component, which contains the temperature information,
and an atmospheric air component from air-filled inclusions are included in the
calculations. Plots of two noble gas concentrations against each other (Xe-Ne, Kr-Ar)
show that the measured concentrations are in general agreement with this simple
model.
Unfortunately the combined mass spectrometric measurement of Ar, Kr and Xe turned
out to be slightly problematic. A separated measurement should solve the corresponding
problems. Furthermore, a lab water standard for noble gases will be prepared to further
examine the measurements in the future.
In this measurement run samples from not only Bunker Cave (Germany) showed
suitable properties for NGT determination but also samples from Katerloch Cave
(Austria) where the water concentration varies between 0.4 to 4 μl per g calcite
which is comparable to the Bunker Cave stalagmites. The air to water volume ratio
is below 0.1 which in principle allows the determination of NGTs with errors in
the range of 1 °C. The calculated NGTs are in the range of the modern cave air
temperature. |
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