0000000000136820
AUTHOR
Sylvia Riechelmann
showing 10 related works from this author
Bunker Cave stalagmites: an archive for central European Holocene climate variability
2012
Holocene climate was characterised by variability on multi-centennial to multi-decadal time scales. In central Europe, these fluctuations were most pronounced during winter. Here we present a record of past winter climate variability for the last 10.8 ka based on four speleothems from Bunker Cave, western Germany. Due to its central European location, the cave site is particularly well suited to record changes in precipitation and temperature in response to changes in the North Atlantic realm. We present high-resolution records of &delta;<sup>18</sup>O, &delta;<sup>13</sup>C values and Mg/Ca ratios. Changes in the Mg/Ca ratio are attributed to past meteoric p…
Sensitivity of Bunker Cave to climatic forcings highlighted through multi-annual monitoring of rain-, soil-, and dripwaters
2017
The last two decades have seen a considerable increase in studies using speleothems as archives of past climate variability. Caves under study are now monitored for a wide range of environmental parameters and results placed in contextwith speleothemdata. The present study investigates trends froma seven year longmonitoring of Bunker Cave, northwestern Germany, in order to assess the hydraulic response and transfer time of meteoric water fromthe surface to the cave. Rain-, soil-, and dripwaterwere collected fromAugust 2006 to August 2013 at a monthly to bimonthly resolution and their oxygen and hydrogen isotope composition wasmeasured. Furthermore, drip rates were quantified. Due to differe…
The magnesium isotope record of cave carbonate archives
2012
Here we explore the potential of magnesium (&delta;<sup>26</sup>Mg) isotope time-series data as continental climate proxies in speleothem calcite archives. For this purpose, a total of six Pleistocene and Holocene stalagmites from caves in Germany, Morocco and Peru and two flowstones from a cave in Austria were investigated. These caves represent the semi-arid to arid (Morocco), the warm-temperate (Germany), the equatorial-humid (Peru) and the cold-humid (Austria) climate zones. Changes in the calcite magnesium isotope signature with time are compared against carbon and oxygen isotope records from these speleothems. Similar to other proxies, the non-trivial interaction of a …
Reconstruction of drip-water δ&lt;sup&gt;18&lt;/sup&gt;O based on calcite oxygen and clumped isotopes of speleothems from Bunker Cave…
2013
Abstract. The geochemical signature of many speleothems used for reconstruction of past continental climates is affected by kinetic isotope fractionation. This limits quantitative paleoclimate reconstruction and, in cases where the kinetic fractionation varies with time, also affects relative paleoclimate interpretations. In carbonate archive research, clumped isotope thermometry is typically used as proxy for absolute temperatures. In the case of speleothems, however, clumped isotopes provide a sensitive indicator for disequilibrium effects. The extent of kinetic fractionation co-varies in Δ47 and δ18O so that it can be used to account for disequilibrium in δ18O and to extract the past dri…
High‐Resolution Proxy Records From Two Simultaneously Grown Stalagmites From Zoolithencave (Southeastern Germany) and their Potential for Palaeoclima…
2020
Two small annually laminated stalagmites from Zoolithencave (southeastern Germany) grew between CE 1821 and 1970 (Zoo‐rez‐1) and CE 1835 and 1970 (Zoo‐rez‐2), respectively. Trace element concentrations were determined by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA‐ICP‐MS). Samples for δ13C and δ18O analyses were micromilled on annual and subannual resolution. Soil and host rock samples were analyzed by X‐Ray Diffraction (XRD) and their elemental concentrations determined via inductively coupled plasma optical emission spectrometer (ICP‐OES). Trace element concentrations in the stalagmites show two groups in the principal component analyses: one with Mg, Ba, and Sr and an…
Calcite Mg and Sr partition coefficients in cave environments: Implications for interpreting prior calcite precipitation in speleothems
2020
Abstract Trace element to Ca ratios in speleothems have emerged as important proxies that reflect local environmental conditions. However, interpretations of speleothem trace element records can be challenging due to various processes. Positive correlations between speleothem Mg/Ca and Sr/Ca have often been interpreted to reflect prior calcite precipitation (PCP), a process potentially modulated by rainfall variability. For quantitative interpretation of PCP, the distribution coefficients for Mg and Sr (DMg and DSr) are required. Here, we use ten cave monitoring calcite and drip water datasets to investigate the influence of temperature and drip water and calcite Mg/Ca and Sr/Ca ratios on s…
Disequilibrium carbon and oxygen isotope fractionation in recent cave calcite: Comparison of cave precipitates and model data
2013
Abstract Speleothem proxy data provide important information in continental palaeo-climate research due to their precise chronology and wide geographic distribution. Despite a continuously growing number of field and numerical studies designed to study stable isotope fractionation effects, many aspects remain a matter of debate. Here, carbon and oxygen isotope ratios from cave drip water and calcite precipitates sampled on watch glasses in the Bunker Cave (Western Germany) are compared with the values expected for isotopic equilibrium. Furthermore, the field data are compared with the results of a numerical model simulating stalagmite growth and stable isotope ratios. Two drip sites with di…
Hydrogeochemistry and fractionation pathways of Mg isotopes in a continental weathering system: Lessons from field experiments
2012
Abstract The potential of magnesium isotope records from cave carbonate archives (speleothems) has been documented but remains underexplored. This is due to the limited knowledge regarding the complex suite of physico-chemical and biological disequilibrium fractionation processes affecting meteoric fluids in the soil zone, the carbonate hostrock and calcite precipitation in the cave. This study presents δ 26 Mg data from a monitored cave in Germany (Bunker Cave) including rain water (δ 26 Mg: − 0.70 ± 0.14‰), soil water (δ 26 Mg: − 0.51 ± 0.10‰) and drip waters (δ 26 Mg: − 1.65 ± 0.08‰) sampled between November 2009 and May 2011. Field precipitation experiments, i.e., calcite precipitat…
Physicochemical characteristics of drip waters: Influence on mineralogy and crystal morphology of recent cave carbonate precipitates
2014
Speleothems are one of the most intensively explored continental archives for palaeoclimate variability. The parameters, however, that control speleothem petrography and its changes with time and space, specifically calcite crystal morphology and carbonate mineralogy, are still poorly understood. In order to shed light on processes and their products, precipitation experiments of recent carbonate crystals on watch glasses and glass plates were performed in seven selected caves. Drip water sites were analysed for their fluid Mg/Ca molar ratio, pH, degree of saturation for calcite and aragonite and drip rates. Corresponding precipitates were analysed with respect to their mineralogy, calcite …
Moroccan speleothem and tree ring records suggest a variable positive state of the North Atlantic Oscillation during the Medieval Warm Period
2013
We present a magnesium (Mg) and strontium (Sr) record from an aragonitic speleothem (Grotte de Piste, Morocco, 34°N; 04°W) providing a reconstruction of effective rainfall from 619 to 1962 AD. The corresponding drip site was monitored over 2 yr for drip water Mg/Ca and Sr/Ca ratios. Results show evidence for prior aragonite precipitation, which can explain negative correlations between speleothem Mg and Sr concentrations. The data shown here have important climate implications concerning the evolution of the North Atlantic Oscillation (NAO). A comparison of the stalagmite data from Grotte de Piste with an updated tree ring based drought reconstruction from Morocco and other NAO related pro…