Hydrological and ecological changes in western Europe between 3200 and 2000 years BP derived from lipid biomarker δD values in lake Meerfelder Maar sediments. (15th September 2017)

• Record Type: Journal Article
• Authors: Rach, O.; Engels, S.; Kahmen, A.; Brauer, A.; Martín-Puertas, C.; van Geel, B.; Sachse, D.
• Is Part Of: Quaternary science reviews. Volume 172(2017)
• Page Start: 44
• Page End: 54
• Publication Date: 2017-09-15
• Subjects: Holocene -- Climate dynamics -- Paleoclimatology -- Western Europe -- Continental biomarkers -- Organic geochemistry -- Stable isotopes -- Vegetation dynamics; Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quascirev.2017.07.019
• Languages: English
• ISSNs: 0277-3791

Abstract

Abstract: One of the most significant Late Holocene climate shifts occurred around 2800 years ago, when cooler and wetter climate conditions established in western Europe. This shift coincided with an abrupt change in regional atmospheric circulation between 2760 and 2560 cal years BP, which has been linked to a grand solar minimum with the same duration (the Homeric Minimum). We investigated the temporal sequence of hydroclimatic and vegetation changes across this interval of climatic change (Homeric climate oscillation) by using lipid biomarker stable hydrogen isotope ratios (δD values) and pollen assemblages from the annually-laminated sediment record from lake Meerfelder Maar (Germany). Over the investigated interval (3200–2000 varve years BP), terrestrial lipid biomarker δD showed a gradual trend to more negative values, consistent with the western Europe long-term climate trend of the Late Holocene. At ca. 2640 varve years BP we identified a strong increase in aquatic plants and algal remains, indicating a rapid change in the aquatic ecosystem superimposed on this long-term trend. Interestingly, this aquatic ecosystem change was accompanied by large changes in δD values of aquatic lipid biomarkers, such as n C21 and n C23 (by between 22 and 30‰). As these variations cannot solely be explained by hydroclimate changes, we suggest that these changes in the δDaq value were influenced by changes in n -alkane source organisms. Our results illustrate that if ubiquitous aquatic lipid biomarkers are derived from a limited pool of organisms, changes in lake ecology can be a driving factor for variations on sedimentary lipid δDaq values, which then could be easily misinterpreted in terms of hydroclimatic changes. Highlights: We present a high-resolution late Holocene biomarker δD record from W Europe. Terrestrial biomarker δDterr records minor hydrological changes between 3.2 and 2.0 cal ka BP. δDterr data are in agreement with other paleoecological data. We observe significant effects of aquatic lipid source changes on the δDaq record. Multiproxy approaches are essential to avoid hydrological misinterpretations.