Abstract:

Loess-paleosol sequences (LPS) play a key role in recording terrestrial paleoenvironmental information across the European Loess Belt (ELB). While the western and eastern regions, as well as the Danube Basin, have been extensively studied, the transition zone corresponding to the territory of Czechia remains sparsely covered by modern high-resolution research, particularly regarding archives predating the Last Glacial cycle. This study aims to fill this gap by presenting a comprehensive paleoenvironmental reconstruction of the 15-meter-thick Dejvice sequence in Prague.
A high-resolution multi-proxy approach was applied, integrating fine-grain pIRIR290 optically stimulated luminescence (OSL) dating, grain-size distribution, magnetic susceptibility (χlf, χfd%), total organic carbon (TOC), stable carbon isotopes (δ13Corg), micromorphology, and paleomalacology. The exposed sequence comprises 17 distinct lithostratigraphic units spanning the last two glacial-interglacial cycles, from Marine Isotope Stage (MIS) 7 to MIS 2. The base of the profile captures older cycles, featuring a weakly developed chernozem and a Paleo Fluvisol with a syngenetic ice-wedge pseudomorph assigned to MIS 7, followed by MIS 6 loess (dated up to 151 ± 11 ka).
The MIS 6 sequence is notably characterized by an unusually thick (4 m) tundra gley with large smooth-surfaced loess dolls, indicating extreme glacial conditions and robust permafrost presence. The subsequent Upper Paleosol Complex (MIS 5) displays strong pedogenic magnetic enhancement driven by the neoformation of ultra-fine superparamagnetic grains. Strikingly, this MIS 5 sequence is highly condensed due to erosional hiatuses; it contains only one well-developed Haplic Chernozem and one Haplic Luvisol (dated ~123–125 ka), entirely lacking the PK II paleosols and intervening loess typical for Central European sequences. The overlying MIS 4 unit consists of a sandy colluvium (up to 48% sand) disrupted by large epigenetic compositewedge pseudomorphs and polygons, reflecting severe permafrost conditions (mean annual air temperature ≤ −4 °C) and solifluction during the MIS 4/3 transition.
MIS 3 is characterized by weak interstadial pedogenesis marked by localized TOC increases (up to 0.53%) and lighter δ13Corg values (-25.1‰). The sequence is topped by MIS 2 loess (25.0 ± 1.6 ka) and tundra gleys containing a typical cold-steppe malacofauna, including Succinella oblonga and Pupilla loessica. Despite the presence of numerous hiatuses and erosional events, the Dejvice profile provides a uniquely preserved, continuous multi-proxy terrestrial record for Central Bohemia. By documenting paleoclimatic shifts predating the Last Glacial Maximum, this study successfully establishes an environmental link between the western and eastern domains of the ELB.