OSL-based chronology of the cold-climate aeolian sand dunes, Moravian Sahara, lower Morava Basin, Czechia

The Moravian Sahara dune field located in southeastern Czechia represents a unique aeolian system preserving the Late Glacial environment. Until now, the main focus has been concentrated on defining its multigenerational development and examining the environmental factors controlling its formation. However, current studies have failed to bring robust chronologies, so environmental and temporal comparisons with the main aeolian phases in Europe could not be made. Here, we present a study combining chronological and environmental interpretations. To do so, four boreholes were drilled to obtain the samples for optically stimulated luminescence, quartz grain morphoscopy and sediment maturity estimation. The results show that the Moravian Sahara dune field developed episodically between the Last Glacial Maximum (LGM) and Younger Dryas, with the peak occurring during the Oldest Dryas. Quartz grain analysis revealed that the phases of wind-blown sand deposition were short and that the dune sediments had three different sources. Furthermore, it appears that the katabatic winds propagated to the study area during the LGM and Late Pleniglacial and were replaced by westerlies since the Oldest Dryas. Finally, the chronology of aeolian activity in the study area shows that Moravian Sahara dune field development was antecedent to the European Sand Belt and shares more similarities with the landforms in the Carpathian Basin located further south.