Palaeoecological study of a Weichselian wetland site in the Netherlands suggests a link with Dansgaard-Oeschger climate oscillation

Abstract

CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. IntroductionIn 2004 a large, more than 4 m deep building excavation was made in Wageningen ( Fig. 1) in order to prepare the foundation of a new university building (so-called Forum Building). Dr Monique Heijmans of the Nature Conservation and Plant Ecology Group of Wageningen University informed the first author about a peat deposit, covered by a lake deposit, as it was exposed in the profiles of the building excavation. The Wageningen-Forum site is situated in a former Saalian tongue basin. During the Weichselian this basin was filled in with alternating fluvial meltwater deposits from the ice-pushed ridges and aeolian cover sands. During relatively humid phases drain water from the ice-pushed ridges caused seepage in the basin and therefore lakes and fens could develop in the depressions in the landscape. Lake sediments and peat deposits were overblown with sand during periods of aeolian activity. The Forum site shows an example of well-preserved peat and lake sediments covered by aeolian sand. In the same tongue basin northwest of Veenendaal a peat deposit of Allerød AbstractBotanical microfossils, macroremains and oribatid mites of a Weichselian interstadial deposit in the central Netherlands point to a temporary, sub-arctic wetland in a treeless landscape. Radiocarbon dates and OSL dates show an age between ca. 54.6 and 46.6 ka cal BP. The vegetation succession, starting as a peat-forming wetland that developed into a lake, might well be linked with a Dansgaard-Oeschger climatic cycle. We suggest that during the rapid warming at the start of a D-O cycle, relatively low areas in the landscape became wetlands where peat was formed.During the more gradual temperature decline that followed, evaporation diminished; the wetlands became inundated and lake sediments were formed. During subsequent sub-arctic conditions the interstadial deposits were covered with wind-blown sand. Apart from changes in effective precipitation also the climate-related presence and absence of permafrost conditions may have played a role in the formation of the observed sedimentological sequence from sand to peat, through lacustrine sediment, with coversand on top. The Wageningen sequence may correspond with D-O event 12, 13 or 14. Some hitherto not recorded microfossils were described and illustrated.Keywords: Dansgaard-Oeschger cycles, macrofossils, non-pollen palynomorphs, Oribatida, pollen...

Holocene changes in forest composition in northern Patagonia responded to climate with little impact of disturbance

“…At the latitude of our study site (40 S), the La Niña (El Niño) phase of ENSO is associated with wet (dry) conditions in summer (Montecinos and Aceituno, 2003). This event might have triggered frequent sediment flux into the Lake Vizcacha, explaining the presence of Glomus, a spore associated with eroded soils (van Geel et al, 1995). This interpretation is also supported by the low values of organic content between 8100e2300 cal yr BP (Fig.…”

The age of the Hengelo interstadial revisited

“…The ages from Oerel were obtained by the enrichment method applied at that time (Grootes, 1977). Van Geel et al (2010) found a clearly expressed warming event dated between 46.6 and 54.6 ka calBP (by a combination of OSL and radiocarbon dating, the latter around the limit of the method) in a peat deposit from the central Netherlands and, based on those datings, correlated it with DeO event 12 or 14. Vaquero et al (2013) in their Spanish rock shelter (see above) identified also a warm interval between 46 and 52 ka BP that they correlated with DeO oscillations 14 to 17.…”

Borderline radiocarbon

“…Here consistent dates between 40 and 60,000 years were obtained, the youngest one by 14 C, and the older ones by OSL dating (Van Geel et al, 2010). Here consistent dates between 40 and 60,000 years were obtained, the youngest one by 14 C, and the older ones by OSL dating (Van Geel et al, 2010).…”

“…An example is the dating of selected seeds from another borderline (in terms of 14 C age) sequence from Wageningen. Here consistent dates between 40 and 60,000 years were obtained, the youngest one by 14 C, and the older ones by OSL dating (Van Geel et al, 2010). More intercomparisons between 14 C and OSL dating of such sequences are underway (Van der Plicht & Wallinga, in preparation).…”