The development of the periglacial dune fields within the central part of the European Sand Belt – insights from the pattern analysis

The age of aeolian deposits and duration of conditions favorable for aeolian processes within the European Sand Belt (ESB) are still debated. Nowadays combined ¹⁴C and OSL data are proper tools to establish the chronology of ESB dunes. However, both methods have significant limitations. They can be used only in existing outcrops limiting spatial coverage of results and making them not reliable for whole dune fields. The second issue is that the oldest dune sediments can be already reworked during dune migration. Finally, the measurement error of OSL data is too high to determine the constructional time of dune fields. To overcome these limitations, we used LiDAR data to examine the pattern properties of 31 dune fields located within the central part of ESB. Dune field pattern is recognized as a self-organizing system, where pattern evolution is a function of constructional time. This is reflected by increasing dune spacing and crest length, a decrease in defect density, and an overall reduction in the statistical variance of these parameters as the pattern matures. Curves describing the relationship between these parameters and constructional time were already established.

Results of the pattern analyses show that studied dune fields represent a wide range of spatial patterns, from irregular parabolic dune fields through a variety of transitional types to well-developed and regular patterns of large transverse dunes. The study confirms that periglacial dune fields undergo the same self-organization of pattern as dune fields located in hot and temperate areas. Regardless of the specific periglacial conditions, the temporal relationship between crest length, spacing, and defect density is preserved. Calculated constructional time for dune fields ranges between 1.2-4.2 ka for defect density, 0.3-5.9 ka for crest length, and 2.2-6.8 ka for spacing, indicating high spatial and temporal variability in the development of dune fields and a lack of zonation regarding to ice-sheet retreat. The coexistence of a few dune fields characterized by different degrees of pattern maturity in close vicinity suggests that the evolution of these dune fields was individual for each site and driven mainly by local events leading to the release of sand, such as subsequent incision of rivers, lowering of groundwater table, forest fires or human-induced deforestation. 

Presented results were obtained with the support of Polish National Science Centre, contracts number 2018/30/E/ST10/00616 and 2021/41/N/ST10/00350.