Holocene climate variability in Central Germany and a potential link to the polar North Atlantic: A replicated record from three coeval speleothems

Abstract

Here, we present high-resolution trace element and stable isotope records from three coeval Holocene stalagmites from the Herbstlabyrinth cave system, Central Germany. All stalagmites were precisely dated using MC-ICPMS 230Th/U-dating. One stalagmite started to grow at 13.62 ± 0.13 ka BP, covering the late Glacial; the other two speleothems started to grow at 11.13 ± 0.08 and 10.26 ± 0.08 ka BP, respectively. The combined record covers the entire Holocene. The interpretation of the different climate proxies is supported by data from a detailed cave monitoring programme. Cold conditions during the Younger Dryas are reflected by intermittent stalagmite growth at the Herbstlabyrinth. The δ18O records are in general agreement with the NGRIP δ18O record on millennial time scales indicating that speleothem δ18O values at the Herbstlabyrinth reflect large-scale climate variability in the North Atlantic area. The 8.2 ka event is clearly visible as a pronounced negative excursion in the δ18O records. In all other proxies, it is not reflected as a major excursion. Correlation and principal component analysis enable us to disentangle the various processes affecting the stable isotope and trace element signals. Phases with higher P, Ba and U concentrations and more negative δ13C values are interpreted as reflecting more productive vegetation above the cave. The negative correlation of Mg with P, Ba and U and the positive correlation with δ13C indicate more recharge during phases of more productive vegetation, probably because of increased rainfall. The majority of the observed phases of reduced vegetation productivity and drier climate coincide with cooler periods in the polar North Atlantic as reflected by a higher abundance of hematite-stained grains (i.e. the Bond events), suggesting a close relationship between terrestrial climate in Central Europe and the polar North Atlantic

TERMITE: An R script for fast reduction of laser ablation inductively coupled plasma mass spectrometry data and its application to trace element measurements

“…We analyzed a section of the Holocene stalagmite HLK2 from the Herbstlabyrinth (HL) cave system, central Germany. HLK2 is 15 cm long and grew on top of a slightly movable block in a small chamber inside the cave system . We chose a small subsection of HLK2, composed of milky, opaque calcite suddenly changing to clear, translucent material (Fig.…”

“…). This section has previously been analyzed by Mischel et al . Here we re‐analyzed the subsection using both spot measurements (100 μm spot size with a midpoint spacing of 125 μm) and line scans with a scan speed of 5 μm s –1 also using a spot size of 100 μm.…”

“…(A) Photograph of stalagmite HLK2 after cutting. Further details are given by Mischel et al . (B) Detail of analyzed section framed by a black box and black line indicating the laser ablation track.…”

Main controls on the stable carbon isotope composition of speleothems

“…This complexity poses a significant challenge for the accurate interpretation of speleothem δ 13 C values, and often limits its utility as a paleoclimate proxy to generalised discussions on overall conditions or broad vegetative transitions (e.g., Genty et al 2003;Holmgren et al 2003). However, in some cases δ 13 C time series proved to be easier to interpret than corresponding δ 18 O time series, in particular at sites where δ 18 O is affected by multiple and competing effects (e.g., Genty et al, 2003;Scholz et al, 2012;Ridley et al, 2015;Mischel et al, 2017).…”

Field Trip A (23 September 2018): geology and geomorphology of Giessen and its surrounding areas

“…11.5 km; Dorsten, 2017). These field studies are accompanied by detailed work on the age determination of dripstone with the Th-U technique (Mischel et al, 2017), the correlation of cave-forming processes with neotectonic events and dated river terraces and geochemical and stabile isotope studies on drip water and cryogenic calcite. For details of these ongoing studies see Mischel et al (2017).…”