EGU21-9619
https://doi.org/10.5194/egusphere-egu21-9619
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Contemporaneously growing speleothems and their value to decipher in-cave processes

Vanessa Skiba1 and Jens Fohlmeister1,2
Vanessa Skiba and Jens Fohlmeister
  • 1Potsdam Institute for Climate Impact Research (PIK), Potsdam, Germany
  • 2German Research Centre for Geosciences (GFZ), Potsdam, Germany

Speleothems have been developed to be valuable climate archives. Albeit much progress has been made to understand speleothem proxies, it remains difficult to differentiate between a direct climate signal and variations, which occurred due to in-cave processes like prior calcite precipitation, CO2 degassing or C exchange between dissolved inorganic C-species and cave air CO2. Here, we analyse palaeoclimate proxies of contemporaneously growing speleothems, which were extracted from the SISALv2 database (Comas-Bru et al., 2020). We argue that differences in their stable O and C isotopic composition as well as in their growth rate can only arise by differences of drip site specific conditions as climate conditions for pairs of contemporaneously growing speleothems are similar. To better understand differences in the isotopic composition and growth rate of contemporaneously growing speleothems, we investigate the in-cave processes by applying a speleothem isotope and growth model. The model is based on a Rayleigh process, which includes CO2 degassing and CaCO3 precipitation, HCO3- <—> H2O buffering as well as CO2 exchange and is able to calculate growth rates. The model accounts for CaCO3 deposition as prior calcite precipitation as well as CaCO3 deposition at the speleothem. We find that C-exchange processes are necessary to explain the linked isotopic and growth rate differences in speleothems.

 

References

Comas-Bru, L., Atsawawaranunt, K., Harrison, S., SISAL working group members (2020): SISAL (Speleothem Isotopes Synthesis and AnaLysis Working Group) database version 2.0. University Of Reading.

How to cite: Skiba, V. and Fohlmeister, J.: Contemporaneously growing speleothems and their value to decipher in-cave processes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9619, https://doi.org/10.5194/egusphere-egu21-9619, 2021.

Corresponding presentation materials formerly uploaded have been withdrawn.