Exploring a new Central European site of paleoclimate reconstruction: First results from Erdmannshöhle (Southern Germany)

Abstract

Here we show preliminary cave monitoring and speleothem results from Erdmannshöhle in Hasel, one of the oldest show caves in Germany. The comprehensive monitoring programme of drip water and cave air started in late summer 2022 and is still ongoing. In addition, we present precise 230Th/U, petrography, and proxy data from several speleothems. Cave temperature and relative humidity loggers show constant values of 10.7 +- 0.5 °C and 100.0% humidity. First results of the cave air CO2 mapping show a strong seasonal ventilation pattern with summer values reaching >6000 ppmV. During winter time, CO2 drops to values < 1700 ppmV, favoring carbonate precipitation during the cold season. Drip water is collected bi-monthly from 10 drip sites located in three chambers of the second horizontal cave level where speleothem growth is still active. First data of drip water stable isotope values agree with the local meteoric water line. In addition, abundances of dissolved minor and trace elements such as Mg, Ba, Sr, K, and Na, as well as anions (e.g., Cl, NO3, PO4, SO4) are analyzed. The data will be compared to the recently precipitated carbonate collected on watch glasses which are mounted on top of drip rate loggers.230Th/U dating of speleothems from Erdmannshöhle is promising due to relatively high U contents in the range of 0.05 - 1 µg/g, and low detrital Th contamination. Analysis of drill cores from 25 stalagmites and flowstones from different cave chambers and cave levels extend the preliminary survey of Becker et al. (2020). The data shows that speleothem growth was active in Erdmannshöhle at least for the last 162 ka (Becker et al. 2020), in particular during past warm interglacial periods and the Holocene. Preliminary exploration of proxy data from two speleothems covering several parts of the Holocene demonstrate the high potential of Central European paleoclimate reconstruction. Stable oxygen records suggest a strong link to North Atlantic climate variability. In addition, carbon isotope and high resolution laser ablation ICPMS trace element records are explored for their paleoclimatic significance.In summary, Erdmannshöhle has excellent preconditions for the continuous reconstruction of past Central European climate, and this comprehensive monitoring effort will provide an important step towards interpreting speleothem proxy data. ReferenceBecker, A., Piepjohn, K., & Schröder-Ritzrau, A. (2020). The Erdmannshöhle near Hasel, SW Germany: karst environment and cave evolution. Swiss Journal of Geosciences, 113(1), 1-25.