Description: The annually laminated record of Lake Belau offers an exceptional opportunity to investigate with high temporal resolution Holocene environmental change, aspects of climate history and human impact on the landscape. A new chronology based on varve counts, 14C-datings and heavy metal history has been established, covering the last 9400 years. Based on multiple varve counting on two core sequences, the easily countable laminated section spans about 7850 varve years (modelled age range c. 9430 to 1630 cal. BP). Not all of the record is of the same quality but approximately 69% of the varves sequence is classified to be of high quality and only c. 5% of low quality. The new chronology suggests dates generally c. 260 years older than previously assumed for the laminated section of the record. The implications for the vegetation and land-use history of the region as well as revised datings for pollen stratigraphical events are discussed. Tephra analysis allowed the identification of several cryptotephra layers. New dates for volcanic eruptions are presented for the Lairg B event (c. 6848 cal. BP, 2s range 6930–6713 cal. BP), the Hekla 4 event (c. 4396 cal. BP, 2s range 4417–4266 cal. BP), and Hekla 3 eruption (c. 3095 cal. BP, 2s range 3120–3068 cal. BP).

Description: Die synchron abgelagerten, jahresgeschichteten Seesedimente des Belauer Sees und des Poggensees (beide Norddeutschland) wurden mikrofaziell untersucht, um die Sedimentationsprozesse während der Trichterbecherzeit zu vergleichen. Dabei wurden in den Seen zeitgleich abgelaufene limnologische Prozesse und Ereignisse festgestellt. Diese wurden als Resultat überregionaler Auslöser (Klima, Witterung) interpretiert. Einige aus Klimaarchiven an anderen Standorten Europas bekannte paläoklimatische Trends und Events wurden auch in der Kernzone der norddeutschen Trichterbecherkultur nachgewiesen. Erstmals entdeckt wurde eine Witterungsanomalie die als Folge von ca. 40 aufeinanderfolgenden Jahren mit Kaltlufteinbrüchen in den Sommern interpretiert werden kann. Diese Phase datiert um ca. 5950 cal BP und könnte mit dem Bond-Event 4 in Verbindung stehen. Insgesamt scheint die Trichterbecherkultur in ein Intervall günstiger Witterungsbedingungen mit warmen Sommern und nicht strengen Wintern eingebettet. Die Phase endet gegen 5275 cal BP abrupt mit einer Abkühlung insbesondere der Sommertemperaturen. Ein weiteres Ergebnis ist die Feststellung asynchron datierender, lokaler Landnutzungseinflüsse in den Einzugsgebieten der Seen. So treten im Poggensee intensive detritisch-mineralische Einträge, die auf Ackerbau und Bodenerosion im Einzugsgebiet zurückgeführt werden können, etwa 350 Jahre früher auf als im Belauer See (5800 resp. 5450 cal BP). Ergänzende Untersuchungen sollten durchgeführt werden, um die Ergebnisse des vorliegenden Zwei- Seen-Vergleichs zu prüfen und präzisere Aussagen über die räumliche Gültigkeit der Witterungsrekonstruktion zu ermöglichen. ------------------- Synchronously deposited annually laminated lake sediments of Lake Belau and Lake Poggensee (both in northern Germany) were investigated microscopically in order to compare the sedimentation processes during Funnel Beaker Times (TRB). Via this comparison palaeolimnological processes and events that occurred synchronously in the lake systems were detected. The processes were interpreted as reflections of limnological responses to supra-regional extrinsic (climate) drivers. Some palaeoclimatic events or trends reported at remote sites in Europe were also verified for the core region of TRB. Evidence of other events, such as the cold summers at ca. 5950 cal BP (probably with sudden frost events), emerged for the first time due to the unique potential of the acquired climate archives. The interval of the Funnel Beaker Culture seems to have experienced a period with favorable weather conditions, with warm summers and not extraordinary severe winters. These conditions terminated abruptly at around 5275 cal BP when the weather (in particular summers) became colder. Another result is the detection of asynchronous changes in sedimentation patterns of Lake Poggensee, which occurred ca. 350 years earlier than in Lake Belau (5800 resp. 5450 cal BP), were ascertained and interpreted as responses to local (land use) drivers, for instance increased detrital input into the lakes indicating agricultural land use and soil erosion in the lake catchment areas. Additional investigations should assure the conclusions made on the base of two lakes and enable a regionalization of the analysis to define the spatial validity of the results more precisely.

Description: Time-series of varve properties and geochemistry were established from varied sediments of Lake Woserin (north-eastern Germany) covering the recent period AD 2010–1923 and the mid-Holocene time-window 6400–4950 varve years before present (vyr BP) using microfacies analyses, x-ray fluorescence (µ-XRF) scanning, microscopic varve chronology, and 14C dating. The microscopic varve chronology was compared with a macroscopic varve chronology for the same sediment interval. Calcite layer thickness during the recent period is significantly correlated to increases in local annual precipitation (r = 0.46, p = 0.03) and reduced air-pressure (r = −0.72, p 〈 0.0001). Meteorologically consistent with enhanced precipitation at Lake Woserin, a composite 500 hPa anomaly map for years with 〉1 standard deviation calcite layer thickness depicts a negative wave train air-pressure anomaly centered over southern Europe, with north-eastern Germany at its northern frontal zone. Three centennial-scale intervals of thicker calcite layers around the mid-Holocene periods 6200–5900, 5750–5400, and 5300–4950 vyr BP might reflect humid conditions favoring calcite precipitation through the transport of Ca2+ ions into Lake Woserin, synchronous to wetter conditions in Europe. Calcite layer thickness oscillations of about 88 and 208 years resemble the solar Gleissberg and Suess cycles suggesting that the recorded hydroclimate changes in north-eastern Germany are modified by solar influences on synoptic-scale atmospheric circulation. However, parts of the periods of thicker calcite layers around 5750–5400 and 5200 vyr BP also coincide with enhanced human catchment activity at Lake Woserin. Therefore, calcite precipitation during these time-windows might have further been favored by anthropogenic deforestation mobilizing Ca2+ ions and/or lake eutrophication.

Description: The recent sediment record of Lake Belau (Schleswig–Holstein, Germany), deposited in the period 1945–2002, was compared with instrumental meteorological and limnological data. The sediments deposited during this period are annually laminated. A varve chronology was established and supported by 137Cs measurements. Micro-facies and diatom assemblage composition analyses were confirmed in thin sections and compared statistically with limnological and meteorological data. Comparison of phytoplankton data with diatom assemblage data from the sediment for the time interval from 1988 to 1999 proved that the sediments reflect limnological processes in the lake and record seasonal changes in the primary producer communities. Among the climatological data, the number of contiguous ice days (days with maximal temperatures ≤0 °C) and the state of the winter NAO are strong predictors for micro-facies development and diatom assemblage composition. Furthermore, solar and local (nutrient input) influences are visible in the diatom assemblage compositions. Our study illustrates the high potential for using analyses of micro-facies and diatom assemblages to reconstruct past weather conditions in varved sediments of Lake Belau.