EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Disentangling climate-dependent stalagmite proxies using radiocarbon timeseries

Steffen Therre1, Jens Fohlmeister2, Sophie F. Warken1,3, Andrea Schröder-Ritzrau1, Ronny Friedrich4, and Norbert Frank1
Steffen Therre et al.
  • 1Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany
  • 2German Federal Office for Radiation Protection (BfS), Berlin, Germany
  • 3Institute of Earth Sciences, Heidelberg University, Heidelberg, Germany
  • 4Curt-Engelhorn-Center Archaeometry, Mannheim, Germany

The transport and incorporation mechanisms of radiocarbon (14C), stable carbon isotopes (δ13C) and trace metal ratios into speleothems have been investigated intensively in the past. This provides a crucial understanding for the detection of climate and ecosystem signals (precipitation, vegetation variability) or even changes in atmospheric composition like radionuclide concentration. The Dead Carbon Fraction (DCF) in tropical settings often revealed a positive correlation with hydrological proxies, highlighting its relation with the amount of soil water infiltration. In contrast, more arid regions can have dominant aged stocks of soil organic matter (SOM) diluting the 14C concentration of the soil CO2, which is responsible for an enhanced decoupling between speleothem DCF and hydrological proxies.

Here, we present a compilation of several new and published stalagmite 14C records in context with the predominant climatic parameters controlling their carbon signature. The records cover humid, tropical climates in Puerto Rico, temperate settings in Northern Turkey, as well as semi-arid alpine caves, and arid locations on the Arabian Peninsula. The range of mean DCF values is extreme, from below 10 to more than 60 % with δ13C values between -10 and 0 ‰. Climate-controlled mechanisms like the sensitivity of vegetation to net-infiltration changes are revealed, especially for more arid regions where aged SOM significantly contributes to stalagmite geochemistry.

In a first application, we revisit a published multi-proxy glacial record of a stalagmite from Socotra Island, which allows us to disentangle the increasing soil infiltration towards Termination I and the resulting long-term DCF trends. This is achieved by exploiting the correlation of a humidity proxy (Mg/Ca) with DCF and implementing a transfer function to correct for soil carbon effects in 14C.

Our approach hints at vast opportunities to better understand the control mechanisms in stalagmite carbon signature and correct for climate-induced effects. Therefore, it can aid future research in the search for stalagmite records which trace, for instance, atmospheric nuclide signals or bear unresolved climate-related trends.

How to cite: Therre, S., Fohlmeister, J., Warken, S. F., Schröder-Ritzrau, A., Friedrich, R., and Frank, N.: Disentangling climate-dependent stalagmite proxies using radiocarbon timeseries, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4875,, 2022.