Buried Late Weichselian thermokarst landscape discovered in the Czech Republic, central Europe

Abstract

Pronounced climatic warming associated with the Late Weichselian Pleniglacial‐to‐Lateglacial transition caused considerable environmental changes throughout the former periglacial zones (in Europe ~53°–46°N). During permafrost degradation and subsequent ground subsidence (i.e. thermokarst processes), the landscape changed rapidly. In this study we investigated a flat mid‐altitude area in south Bohemia, Czech Republic, lying close to the southern limit of the Weichselian permafrost. We discovered palaeo‐lake basins with sedimentary infillings up to 11 m in depth. According to radiocarbon and palynostratigraphical dating, these basins were formed at the onset of the Late Pleniglacial‐to‐Lateglacial transition, whereas the smaller depressions were formed later. We suggest that the basins resulted from thermal and fluvio‐thermal erosion of the former permafrost and represent remnants of discontinuous gullies and possibly collapsed frost mounds (pingo/lithalsa scars). The formation of this a fossil thermokarst landscape was climatically driven and multiple phased, with the major phase during the climatic warming and wetting at the onset of GI‐1e (Bølling) and the minor phase during GI‐1c (Allerød). This study enhances knowledge of the palaeogeography of the former European periglacial zone by showing that Late Pleistocene thermokarst activity could have had a significant impact on the evolution of the landscape of at least some regions of central Europe along the southern limit of the continuous permafrost zone. The research also points to a similar history for the physical transformation of the landscape of the former European periglacial zone and current thermokarst landscapes and could be a valuable source of information with respect to the future transformation of the Arctic under conditions of ongoing global warming.

Magdalenian and Epimagdalenian chronology and palaeoenvironments at Kůlna Cave, Moravia, Czech Republic

“…Indeed, while gradual climatic warming did occur in the millennia following the LGM, evidence suggests the climate of Central Europe remained predominantly cold until the onset of Late Glacial Interstadial (GI-1) (Huijzer and Vandenberghe 1998 ; Vočadlová et al 2015 ). Sedimentological archives for the region show significant landscape instability and high rates of erosion, which would have impeded the development of organic soils, while braided river systems characterised surface hydrological features (Pokorný 2002 ; Žák et al 2012 ; Hošek et al 2014 , 2019 ; Kadlec et al 2015 ; Fig. 6f and g ).…”

“…However, a change in hydrological conditions during the latter part of GS-2.1a is evidenced by the increasing abundance of Cyperaceae pollen, a species associated with marshland environments (Pokorný 2002 ; Kuneš et al 2015 ). It has been suggested that the development of these waterlogged environments is linked to permafrost thaw and the development of thermokarst conditions, which began around 17 ka in Central Europe, and to increased precipitation at 16–15 ka (Pokorný 2002 ; Žák et al 2012 ; Hošek et al 2014 , 2019 ).…”

“…Chironomid inferred temperatures show summer averages of 13–14 o C in central Poland and 14–17 o C in western Slovakia (Płóciennik et al 2011 ; Šolcová et al 2020 ). Higher precipitation amounts are indicated from rising lake levels in the southern Czech Republic (Hošek et al 2017 , 2019 ). While in certain environmental contexts increased moisture may lead to a decrease in δ 15 N values (e.g.…”

“…2 0 1 5 ) . Sedimentological archives for the region show significant landscape instability and high rates of erosion, which would have impeded the development of organic soils, while braided river systems characterised surface hydrological features (Pokorný 2002;Žák et al 2012;Hošek et al 2014Hošek et al , 2019Kadlec et al 2015; Fig. 6f and g).…”

Periglacial gully erosion on the east European plain and its recent analog at the Yamal peninsula

“…The main part of these dry valleys (the Russian term is «balka») was formed during erosional events of the Late Quaternary (Eremenko et al 2011;Matoshko 2012) in the periglacial conditions with the permafrost. This type of ancient erosion features, some buried, some renewed by the modern erosion, is widespread in Europe (Larsen et al 2016;Hošek et al 2019), Northern America (Bettis et al 1985), and Australia (Prosser et al 1994). The reconstruction of the environmental conditions of Quaternary gullies initiation and evolution are critical for understanding their morphology and history.…”