English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

Determination of aragonite trace element distribution coefficients from speleothem calcite-aragonite transitions

MPS-Authors
/persons/resource/persons101034

Jochum,  K. P.
Climate Geochemistry, Max Planck Institute for Chemistry, Max Planck Society;

External Resource
No external resources are shared
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available
Citation

Wassenburg, J. A., Scholz, D., Jochum, K. P., Cheng, H., Oster, J., Immenhauser, A., et al. (2016). Determination of aragonite trace element distribution coefficients from speleothem calcite-aragonite transitions. Geochimica et Cosmochimica Acta, 190, 347-367. doi:10.1016/j.gca.2016.06.036.


Cite as: http://hdl.handle.net/11858/00-001M-0000-002C-E68D-2
Abstract
The processes that govern the incorporation of (trace) elements into speleothems can often be linked to environmental changes. Although element incorporation into speleothem calcite is now reasonably well understood, current knowledge regarding trace element variability in speleothem aragonite is very limited. Of particular interest is whether trace element distribution coefficients are above or below one in order to assess the extent to which prior aragonite precipitation has affected speleothem aragonite trace element records. This study uses nine calcite-to-aragonite transitions in seven speleothems from diverse environmental settings to derive the first quantitative estimates of the distribution coefficients for several elements in speleothem aragonite: D-Mg(Ar) = 9.7E-5 +/- 9.01E-5, D-Ba(Ar) = 0.91 +/- 0.88, D-Sr(Ar) = 1.38 +/- 0.53, and D-U(Ar) = 6.26 +/- 4.54 (1 sigma SD). For one speleothem from western Germany, the distribution coefficients are generally higher, which is potentially related to the very low growth rates (< 11 mu m/year) of this sample. In particular, D-Sr(Ar) appears to show a negative correlation with growth rate when growth rate is below 20 mu m/year. In summary, our results demonstrate that speleothem aragonite D-Mg(Ar) is below one, D-U(Ar) is considerably above one, and D-Sr(Ar) is above one or close to unity. For D-Ba(Ar), reaching a similar conclusion is difficult due to the relatively high uncertainty. Enhanced prior aragonite precipitation will thus result in lower U and higher Mg concentrations in speleothem aragonite, although in many cases Mg in speleothem aragonite is most likely dominated by other processes. This result suggests that U concentrations in aragonitic stalagmites could serve as a very effective proxy for palaeo-rainfall. (C) 2016 Elsevier Ltd. All rights reserved.