Schlagwort: Datierung

@proceedings{klose2023poster,

title = {Timing of Dansgaard-Oeschger events in Central Europe based on three precisely dated speleothems from Bleßberg Cave, Germany},

author = {J. Klose and D. Scholz and M. Weber and H. Vonhof and B. Plessen and S. Breitenbach and N. Marwan},

editor = {Summer School on Speleothem Sciences 2023, Sao Paulo},

url = {https://bbh.pik-potsdam.de/wp-content/uploads/2024/09/klose_SummerschoolSaoPaulo2023.pdf},

year  = {2023},

date = {2023-08-07},

urldate = {2023-08-07},

abstract = {The last glacial period and especially Marine Isotope stage 3 (MIS 3, ca. 57 - 27 ka) was characterized by various climate oscillations (i.e., rapid increases in temperature, followed by a gradual cooling, the Dansgaard-Oeschger (D/O) events), which were first discovered in Greenland ice cores. Although their causes are still not fully understood, clear evidence for their supra-regional character was found in various climate records around the globe. However, European speleothem samples, which grew during MIS 3, are limited and mainly restricted to alpine regions, where glacier meltwater enabled speleothem growth, and to south/south-western parts of Europe characterised by a generally warmer climate. This led to the opinion that it was too cold and/or too dry in central Europe for speleothem growth. Here we present three speleothem (flowstone) records from Bleßberg Cave, Germany, which grew during MIS 3. 

All flowstones show episodical growth patterns with distinctive, thin growth phases. Potential contamination deriving form detrital material deposited during hiatuses between individual growth phases, open-system behaviour around the hiatuses and the limited thickness of the growth layers are the biggest challenges during sampling for 230Th/U dating. By combination of different sampling techniques (i.e., laser ablation and micro-milling) in addition to the common approach of handheld drilling and due to the relatively high 238U concentration of the samples (approx. 0.4 – 1 µg/g), we were able to date even the thinnest growth layers (< 2 mm) of the Bleßberg flowstones with a very high precision (i.e., with 2σ-age uncertainties of a few hundred years or even lower).

The timing of the growth phases of the Bleßberg flowstones correlates with several D/O events recorded in the Greenland ice cores. This proves that at least some phases of MIS 3 had favourable climate conditions for speleothem growth in Central Europe. In addition, the analysis of the stable oxygen and carbon isotopes (δ18O and δ13C) for all three flowstones revealed several D/O events, which have not been recorded in any other speleothem from central Europe so far. This will enhance our understanding of climate variability during MIS 3 and specific D/O events in central Europe.},

howpublished = {Poster},

note = {Summer School on Speleothem Sciences 2023, Sao Paulo},

keywords = {},

pubstate = {published},

tppubtype = {proceedings}

}

@proceedings{klose2023,

title = {Timing and progression of Dansgaard-Oeschger events in Central Europe based on three precisely dated speleothems from Bleßberg Cave, Germany},

author = {J. Klose and D. Scholz and M. Weber and H. Vonhof and B. Plessen and S. Breitenbach and N. Marwan},

editor = {XXI INQUA Conference, Rome (Italy)},

year  = {2023},

date = {2023-07-19},

urldate = {2023-07-19},

abstract = {Speleothems can be dated with unprecedented precision using U-series disequilibrium methods and provide numerous climate proxies, such as stable oxygen (δ18O) and carbon isotopes (δ13C) or trace elements, resulting in long, sometimes continuous climate proxy records. Therefore, speleothems have great potential for reconstruction of past climate variability during Marine Isotope Stage (MIS) 3 and precise determination of the timing and duration of Dansgaard-Oeschger (D/O) events. While first discovered in Greenland ice cores, various speleothem records around the globe provided clear evidence for the supra-regional character of the D/O events. However, MIS 3 speleothem records from Central Europe are very limited. Here we present three spleothem (flowstone) MIS 3 records from Bleßberg Cave, Germany.



All flowstones show episodic growth with distinctive, partially very thin (<2 mm) growth phases, interrupted by visible hiatuses consisting of detrital material. Precise and accurate 230Th/U dating of the individual growth phases is challenging due to potential detrital contamination from these layers. Combining different sampling and analytical techniques, we were able to date even the thinnest growth layers with very high precision, i.e., 2σ-age uncertainties of at most a few hundred years.



The timing of the growth phases aligns with several D/O events, which have not been recorded in other Central European speleothems yet. The δ18O and δ13C records of all three flowstones are highly correlated which suggests a dominant process influencing both isotope systems. Comparison with the Sr and Mg records provides evidence for a strong influence of Prior Calcite Precipitation (PCP) in the aquifer above and inside the cave on the stable isotope and trace element signals. In addition, all proxy records are interpreted as evidence for past changes in precipitation and vegetation density and document a clear trend from more humid climate during early MIS 3 (ca. 57 – 50 ka) to less humid conditions during mid and late MIS 3 (ca. 45 – 30 ka).



Our multi-proxy approach thus allows us not only to precisely determine the timing, duration, and progression of several D/O events, but also to deepen our general understanding of climate variability during MIS 3 in Central Europe.},

howpublished = {Poster},

note = {XXI INQUA Conference, Rome (Italy)},

keywords = {},

pubstate = {published},

tppubtype = {proceedings}

}

@proceedings{klose2022,

title = {Timing of Dansgaard-Oeschger events in Central Europe based on three precisely dated speleothems from Bleßberg Cave, Germany},

author = {J. Klose and M. Weber and H. Vonhof and B. Plessen and S. Breitenbach and N. Marwan and D. Scholz},

editor = {KR9 in Innsbruck, 2022},

url = {https://bbh.pik-potsdam.de/wp-content/uploads/2024/09/klose_KR9-Innsbruck2022.pdf},

year  = {2022},

date = {2022-07-19},

urldate = {2022-07-19},

abstract = {The last glacial period and especially Marine Isotope stage 3 (MIS 3, ca. 57 - 27 ka) was characterized by various climate oscillations (i.e., rapid increases in temperature, followed by a gradual cooling, the Dansgaard-Oeschger (D/O) events), which were first discovered in Greenland ice cores. Although their causes are still not fully understood, clear evidence for their supra-regional character was found in various climate records around the globe. However, European speleothem samples, which grew during MIS 3, are limited and mainly restricted to alpine regions, where glacier meltwater enabled speleothem growth, and to south/south-western parts of Europe characterised by a generally warmer climate. This led to the opinion that it was too cold and/or too dry in central Europe for speleothem growth. Here we present three speleothem (flowstone) records from Bleßberg Cave, Germany, which grew during MIS 3. 

All flowstones show episodical growth patterns with distinctive, thin growth phases. Potential contamination deriving form detrital material deposited during hiatuses between individual growth phases, open-system behaviour around the hiatuses and the limited thickness of the growth layers are the biggest challenges during sampling for 230Th/U dating. By combination of different sampling techniques (i.e., laser ablation and micro-milling) in addition to the common approach of handheld drilling and due to the relatively high 238U concentration of the samples (approx. 0.4 – 1 µg/g), we were able to date even the thinnest growth layers (< 2 mm) of the Bleßberg flowstones with a very high precision (i.e., with 2σ-age uncertainties of a few hundred years or even lower).

The timing of the growth phases of the Bleßberg flowstones correlates with several D/O events recorded in the Greenland ice cores. This proves that at least some phases of MIS 3 had favourable climate conditions for speleothem growth in Central Europe. In addition, the analysis of the stable oxygen and carbon isotopes (δ18O and δ13C) for all three flowstones revealed several D/O events, which have not been recorded in any other speleothem from central Europe so far. This will enhance our understanding of climate variability during MIS 3 and specific D/O events in central Europe.},

howpublished = {Poster},

note = {KR9 Konferenz in Innsbruck},

keywords = {},

pubstate = {published},

tppubtype = {proceedings}

}

@proceedings{klose2021,

title = {Determination of phases of warm climate during MIS 3 in Central Europe based on precisely dated speleothems from Bleßberg Cave, Germany},

author = {Jennifer Klose and Denis Scholz and Sebastian F. M. Breitenbach and Birgit Plessen and Hubert Vonhof},

editor = {GeoKarlsruhe 2021: Sustainable Earth – From processes to resources},

year  = {2021},

date = {2021-09-22},

urldate = {2021-09-22},

abstract = {Speleothems provide a great opportunity for paleoclimate reconstruction because they occur almost worldwide and can be dated very precisely using the U-series disequilibrium method. The most commonly used climate proxies are stable isotope values (δ18O and δ13C) and trace elements. However, these are influenced by a variety of surface and in-cave processes, which results in a non-trivial interpretation of the speleothem proxy signals.



The last glacial period and in particular the Marine Isotope Stage (MIS) 3 is, compared to the recent warm phase, the Holocene, characterised by larger climate oscillations. These are detectable in δ18O records from Greenland ice cores and also climate archives in Europe, such as pollen or tree ring records. Unfortunately, little direct proxy evidence is available from central Europe, and the climatic and environmental conditions during MIS 3 remain largely enigmatic. Speleothem records from central Europe during MIS 3 are limited due to cold climate conditions and mainly restricted to the warmer southern or alpine regions.



Here we present the first results of two flowstones from Bleßberg Cave in Germany. Preliminary 230Th/U-ages make these flowstones the most northern continental growth of speleothems during MIS 3 in central Europe. Thus, these samples provide the unique opportunity to reconstruct climate variability during parts of the last glacial period. With the combination of several different proxies, such as stable isotopes, trace elements and the results from cave monitoring, we will be able to obtain detailed insights into environmental conditions in central Europe during MIS 3 and the Late Glacial.},

howpublished = {Poster},

note = {GeoKarlsruhe 2021: Sustainable Earth – From processes to resources, Karlsruhe},

keywords = {},

pubstate = {published},

tppubtype = {proceedings}

}