Environmental responses to Lateglacial climatic fluctuations recorded in the sediments of pre‐Alpine Lake Mondsee (northeastern Alps)

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.

Late Neolithic Mondsee Culture in Austria: living on lakes and living with flood risk?

“…The 2 m-long segments of the two piston cores and the gravity cores were then visually correlated by using distinct lithological marker layers, resulting in a ca. 15 m-long continuous composite profile, which covers the complete Holocene and Late Glacial sedimentation history of Lake Mondsee (for further details see Lauterbach et al (2011). The completeness of the detrital layer record in the core recovered from 62 m water depth and thus 6 m above the deepest part has been proven by detailed micro-stratigraphic comparison of short cores from both locations (Swierczynski et al, 2013).…”

“…Klee and Schmidt, 1987;Schultze and Niederreiter, 1990;Schmidt, 1991;Lauterbach et al, 2011) and more specifically of past changes in flood frequencies (Swierczynski et al, 2012). The present study of Lake Mondsee sediments focuses on flood and debris flow event layer deposition between 7000 and 4000 varve years (vyr) BP, providing information about hydrological changes within this interval at high temporal resolution.…”

“…In addition, aiming at establishing a varve chronology for the Lake Mondsee sediments, continuous microscopic varve counting and thickness measurements were carried out in the distinctly laminated uppermost part of the Holocene sediment record (0-610 cm), whereas for the lowermost part (610-1129 cm) a varve-based sedimentation rate chronology was established. A detailed description of the microfacies of the Lake Mondsee sediments and the development of the Holocene varve chronology is given by Lauterbach et al (2011). The present study focuses on the interval between 585 and 840 cm composite depth of the Lake Mondsee sediment record.…”

“…2) has been adopted from Lauterbach et al (2011) with a slight change. According to a second independent varve count from present day back to 3878 vyr BP, 7 varves had to be subtracted from the original Lauterbach et al (2011) chronology. The resulting varve chronology for the study interval has been confirmed by independent AMS 14 C dating (Fig.…”

“…Comparison of the primary varve-based age model (given with a counting uncertainty of ±50 yr as dashed lines) of the Lake Mondsee record (Lauterbach et al, 2011) and a secondary radiocarbon-based age model (2σ probability range in grey), which has been established using OxCal 4.1 (Ramsey, 1995(Ramsey, , 2001(Ramsey, , 2008 to evaluate the reliability of the varve chronology. Individual AMS 14 C dates from terrestrial plant macrofossils, which are included in the radiocarbon-based age model are given with their 2σ probability ranges.…”