Early development of late vistulian (weichselian) lacustrine sediments in the zabieniec swamp (central Poland)

Abstract

The early sedimentological and ecological developmental stages of a late Vistulian lake in the Zabieniec swamp near Lódz (central Poland) were analysed by radiometric dating, changes in the frequency of specimens and species composition of Cladocera and multivariate statistical analysis (DCA). The longevity of the lake resulted in a fairly complete sedimentary record from approximate-ly 22 ka to 11 ka cal BP. Species composition and the variability in the frequency of Cladocera spec-imens has made it possible to distinguish eleven zones of their development, which are well correlat-ed with radiocarbon data. The results were compared to those from other sites of north and central Eu-rope. The initial Cladocera development comprises the richest and oldest late Vistulian Cladocera record in Europe. These cladoceran assemblages show that a deep, oligotrophic, moderately cold-water lake was present at the beginning. It appears that the cladoceran development was mainly due to climate change, but also to changes in locally prevailing conditions in the water body. The high frequency of cladocerans, as well as the presence of cladoceran taxa preferring warmer water, was noted before approximately 16 ka BP. The biota suggests that the Oldest Dryas cooling was not se-vere and fairly variable in terms of humidity and temperature. The changes in Cladocera composition give evidence of what is described as the Intra-Bølling Cold Oscillation. It is also concluded that the Bølling is represented by two phases in the Zabieniec lake sediments. © 2012 Silesian University of Technology, Gliwice, Poland.