Klima- und Umweltvariabilität im späten Mittelpleistozän im Bereich der paläolithischen Fundstellen von Schöningen, Norddeutschland
Zusammenfassung der Projektergebnisse
The Lower Paleolithic sites in the open-cast lignite mine of Schöningen, eastern Lower Saxony, have become internationally renown because of their worldwide oldest wooden hunting weapons associated with abundant faunal remains. Concurrently, the extraordinary complete sequence of Middle Pleistocene sediments allows for high-resolution environmental research contributing to the understanding of past climate variability and early human habitats about 300,000 years ago. This project aimed to reconstruct the Reinsdorf mid-interglacial to the succeeding early glacial transition and past depositional environment at the paleo-lakeshore, the present-day excavation sites. Three sediment sequences from two sites, horizontally distributed sediments blocks, representing 2-D time-constrained snapshots of the archeologically most important horizon, and a multi-proxy approach were used to reconstruct qualitatively and quantitatively, temperature, salinity, lake level, trophic state, and lakeshore habitat variations. In order to decipher the characteristics of lakeshore development, ostracods, diatoms, charophytes as well as geochemical proxies (e.g. TOC, CaCO3, and stable isotopes) were analyzed and results compared with existing data from diverse disciplines such as palynology, sedimentology, and plant macro remains. Biological and geochemical indicators document repeated major environmental changes from full interglacial conditions to alternating cool steppe and boreal forest steppe phases. Overall, six and seven major development stages were determined for the Reference Profile 13 II (2003) and Para-Reference Profile 13 II (2014) + Zeugenblock 13 II (2018), respectively. A shallow, productive, alkaline lake with increased salinities existed throughout most of this transitional phase, although periods of dry or only temporarily flooded conditions are indicated by the absence of aquatic microfossils. Habitat instability and stream inflows were traced by increased abundances of small fragilarioid diatoms and mesorheophilic ostracods. The elephant remains were deposited during a transitional phase of boreal forest into dryer and cooler steppe environments, likely marked by increasing dryness, seasonality, and landscape instability. This study provides first quantitative salinity reconstructions, showing values in the β-oligohaline range, and refined lake level assessments pointing to generally less than 2 m water depth. Carbonate-rich inflows from the Elm ridge into the paleolake at the study site as well as increased influence of uprising saline groundwater, influenced by changes in catchment vegetation cover, are documented. Ostracod-based quantitative temperature reconstructions indicate at least around 2 °C colder winter temperatures and probably similar summer temperatures during the steppe phases compared to present-day. The sediment level underlying the important “spear horizon” shows a phase of increased lake levels and development of a diverse fauna and flora at the lakeshore during a more continental climate. Results thereby depict an attractive living and hunting environment for early humans during a phase of generally cooler temperatures and increased landscape instability at the transition into a glacial period. The find horizon itself is characterized at site 13 II by the continuous, upward decreasing diatom occurrences, suggesting either submerged conditions or at least temporary water coverage. Dating results suggest an allocation of the Reinsdorf sequence into Marine Isotope Stage (MIS) 9 and of the Reinsdorf Interglacial into MIS 9e. In order to further evaluate this debated correlation, we compared the climate evolution derived from biological and geochemical proxy analyses during the Reinsdorf Interglacial and succeeding climatic oscillations with environmental variations documented in other MIS 9 records. Overall, similar warm and cool patterns and even short-term variations comparable to the MIS 9 substages are displayed in the Reinsdorf sequence. This project thereby contributes to solve the controversially debated stratigraphic position of the Reinsdorf Interglacial. In general, the analysis and interpretation of several different proxies (aquatic/terrestrial, biological/geochemical) helped to overcome challenges arisen from the variable preservation of aquatic microfossils. Furthermore, this project provides an excellent example of the effectiveness of interdisciplinary investigations combining multiple paleoenvironmental analyses with archeology and dating methods. https://www.helmstedter-nachrichten.de/helmstedt/schoeningen-suedkreis/article211928165/Was-die-Steinzeit-fuer-die-Zukunft-lehrt.html http://geohorizon.de/2017/08/17/die-klima-und-umweltvariabilitaet-der-letzten-300-000-jahre-am-beispiel-eines-sees-in-schoeningen/
Projektbezogene Publikationen (Auswahl)
- (2017). Climate and environmental variability during the late Middle Pleistocene in Schöningen - New research approaches and prospects. Symposium: 25 years of Palaeolithic Research at Schöningen (Germany), Leiden, The Netherlands
Krahn, K.J., Urban, B. & Schwalb, A.
- (2018). Project: Climate and environmental variability during the late Middle Pleistocene in Schöningen – New research approaches and prospects. Schöningen project colloquium 2018, Germany
Krahn, K.J., Schwalb, A., Tucci, M. & Urban, B.
- (2018). Was uns Millionen kleiner Schalen über das Klima und die Umwelt vergangener Zeiten verraten können. In: Terberger, T., Böhner, U., Hillgruber, F., Kotula, A. (Eds), 300.000 Jahre Spitzentechnik. Der altsteinzeitliche Fundplatz Schöningen und die frühesten Speere der Menschheit. Archäologie in Deutschland. wbg Theiss, 119-120
Krahn, K.J., Schwalb, A.
- (2019). High-resolution sedimentological, pollen and aquatic microfossil analysis of Middle Pleistocene lakeshore deposits of paleolithic site Schöningen 13 II-4, Germany. INQUA 2019, Dublin
Tucci, M., Krahn, K.J., Urban, B. & Schwalb, A.
- (2019). Middle Pleistocene interglacial environmental changes inferred from aquatic microfossils at the paleolithic site of Schöningen, Germany. INQUA 2019, Dublin
Krahn, K.J., Pilgrim, J., Urban, B., Tucci, M. & Antje Schwalb, A.
- Klima- und Umweltvariabilität im mittleren Pleistozän von Schöningen – Offene Fragen und Lösungsansätze mit Bioindikatoren. In: Geopark-Trägerverein Braunschweiger Land - Ostfalen e.V. (Eds), Wechselbeziehungen zwischen Mensch und Umwelt – Vergangenheit, Gegenwart und Zukunft im Braunschweiger Land und seinem Umfeld. Gaussiana, Schriftenreihe Geopark Harz. Braunschweiger Land. OstfalenHeft 1, 112-117
Krahn, K.J., Tucci, M., Schwalb, A. & Urban, B.
