Understanding the deglacial relationship between carbon isotopes and temperature in stalagmites from Western Europe
- 1Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK (franziska.lechleitner@earth.ox.ac.uk)
- 2Swiss Federal Institute for Forest, Snow and Landscape Research, Zürcherstrasse 111 8903 Birmensdorf, Switzerland
- 3Laboratory for Ion Beam Physics, ETH Zürich, Otto-Stern-Weg 5, 8093 Zürich, Switzerland
- 4Department of Earth Sciences, ETH Zürich, Sonneggstrasse 5, 8092 Zürich, Switzerland
The last deglaciation was a period of rapid and profound climatic change in Western Europe. Speleothem carbon isotope (δ13C) records from mid-latitude Western Europe have consistently shown large and reproducible excursions over this time period, strikingly similar to available temperature reconstructions from other archives. The mechanism behind the temperature sensitivity of speleothem δ13C, however, remains poorly constrained, due to the complex interplay of multiple processes affecting this proxy.
Here we use a multi-proxy approach and forward modelling of karst processes to investigate what drives the response of speleothem δ13C to the last deglaciation in Western Europe. We present new proxy data (14C and δ44Ca) from speleothem Candela from El Pindal Cave, northern Spain, which covers the period from the Last Glacial Maximum (25 ka BP) to the Early Holocene (8 ka BP). Previously published stable isotope data (Moreno et al., 2010) revealed a pronounced decrease in δ13C over the deglaciation (~8‰ VPDB) which closely tracks regional temperature records from the Iberian Margin. We make use of the different sensitivities of ancillary proxies (14C, Mg/Ca, and δ44Ca) to processes in soil and karst to quantify their relative importance on the δ13C shift. For this, we use the forward modelling software CaveCalc (Owen et al., 2018) to generate a large ensemble of possible solutions, from which the ones closest matching the data are chosen and evaluated.
Our preliminary results suggest that in-cave and karst processes (carbonate host rock dissolution and reprecipitation) cannot explain the full amplitude of the δ13C shift over the deglaciation, and that changes in soil δ13C are to some extent translated to the speleothem carbonate δ13C. The possibility of quantitatively disentangling processes in the soil from other karst processes could allow the reconstruction of past soil activity from speleothems.
References:
Moreno, A., Stoll, H., Jiménez-Sánchez, M., Cacho, I., Valero-Garcés, B., Ito, E., Edwards, R.L., 2010. A speleothem record of glacial (25-11.6 kyr BP) rapid climatic changes from northern Iberian Peninsula. Glob. Planet. Change 71, 218–231. doi:10.1016/j.gloplacha.2009.10.002
Owen, R.A., Day, C.C., Henderson, G.M., 2018. CaveCalc: A new model for speleothem chemistry & isotopes. Comput. Geosci. doi:10.1016/J.CAGEO.2018.06.011
How to cite: Lechleitner, F. A., Day, C. C., Wilhelm, M., Haghipour, N., Kost, O., Henderson, G. M., and Stoll, H. M.: Understanding the deglacial relationship between carbon isotopes and temperature in stalagmites from Western Europe, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7466, https://doi.org/10.5194/egusphere-egu2020-7466, 2020.
