Environmental responses to Lateglacial climatic fluctuations recorded in the sediments of pre‐Alpine Lake Mondsee (northeastern Alps) |
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| Authors: | Stefan Lauterbach Achim Brauer Nils Andersen Dan L Danielopol Peter Dulski Matthias Hüls Krystyna Milecka Tadeusz Namiotko Milena Obremska Ulrich Von Grafenstein Declakes Participants |
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| Institution: | 1. GFZ German Research Centre for Geosciences, Section 5.2 ‐ Climate Dynamics and Landscape Evolution Potsdam, Germany;2. Leibniz Laboratory for Radiometric Dating and Stable Isotope Research, Christian‐Albrechts‐University, Kiel, Germany;3. Austrian Academy of Sciences, Institute for Limnology, Mondsee, Austria;4. Department of Biogeography and Palaeoecology, Faculty of Geographical and Geological Science, Adam Mickiewicz University, Poznań, Poland;5. Laboratory of Limnozoology, Department of Genetics, University of Gdańsk, Gdańsk, Poland;6. Laboratoire des Sciences du Climat et de l'Environnement, UMR CEA‐CNRS, Gif‐sur‐Yvette, France |
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| Abstract: | Investigation of the sedimentary record of pre‐Alpine Lake Mondsee (Upper Austria) focused on the environmental reaction to rapid Lateglacial climatic changes. Results of this study reveal complex proxy responses that are variable in time and influenced by the long‐term evolution of the lake and its catchment. A new field sampling approach facilitated continuous and precisely controlled parallel sampling at decadal to sub‐annual resolution for µ‐XRF element scanning, carbon geochemistry, stable isotope measurements on ostracods, pollen analyses and large‐scale thin sections for microfacies analysis. The Holocene chronology is established through microscopic varve counting and supported by accelerator mass spectrometry 14C dating of terrestrial plant macrofossils, whereas the Lateglacial age model is based on δ18O wiggle matching with the Greenland NGRIP record, using the GICC05 chronology. Microfacies analysis enables the detection of subtle sedimentological changes, proving that depositional processes even in rather large lake systems are highly sensitive to climate forcing. Comparing periods of major warming at the onset of the Lateglacial and Holocene and of major cooling at the onset of the Younger Dryas reveals differences in proxy responses, reflecting threshold effects and ecosystem inertia. Temperature increase, vegetation recovery, decrease of detrital flux and intensification of biochemical calcite precipitation at the onset of the Holocene took place with only decadal leads and lags over a ca. 100 a period, whereas the spread of woodlands and the reduction of detrital flux lagged the warming at the onset of the Lateglacial Interstadial by ca. 500–750 a. Cooling at the onset of the Younger Dryas is reflected by the simultaneous reaction of δ18O and vegetation, but sedimentological changes (reduction of endogenic calcite content, increase in detrital flux) were delayed by about 150–300 a. Three short‐term Lateglacial cold intervals, corresponding to Greenland isotope substages GI‐1d, GI‐1c2 and GI‐1b, also show complex proxy responses that vary in time. Copyright © 2011 John Wiley & Sons, Ltd. |
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| Keywords: | Lateglacial climate lake sediments Austria sediment microfacies µ ‐XRF scanning pollen stable isotopes |
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