Late-Holocene evolution of a floodplain impounded by the Smrdutá landslide, Carpathian Mountains (Czech Republic)

Abstract

Landslides affecting narrow mountainous valleys might significantly determine sedimentation dynamics of floodplains. We present here a detailed study of the sedimentary archive within a landslide-controlled impounded floodplain (Smrdutá site, Czech Flysch Carpathians) using geochronological ( 14 C and 137 Cs), sedimentological and pollen evidence. A sedimentary sequence deposited above the landslide dam points to three highly discontinuous and instantaneous depositional events dated to 4.6 and 2.0 cal. ka BP, whereas the last cycle started approximately in the 17-18th centuries and has continued to recent times. Such sedimentary pulses characterized by the duration of several decades to a few centuries originated as a consequence of the blockage and/or reduction of the valley floor width by successive long-runout landslides from a slope formed by tectonically and lithologically anisotropic flysch bedrock. Stages of mass movement activity revealed by the Smrdutá landslide correlate well with major humid late-Holocene oscillations suggesting its high sensitivity to century-scale climatic deteriorations. The character of lithological units forming individual sedimentary pulses, erosional hiatuses and sedimentary traces caused by the July 1997 extreme flood indicate a decisive role of large flood events during accretion and erosion of the floodplainimpounded section.

Holocene reactivations of catastrophic complex flow-like landslides in the Flysch Carpathians (Czech Republic/Slovakia)

“…This study presents new data and reviews previously published information (Baroň, 2007;Klimeš et al, 2009;Pánek et al, 2009aPánek et al, ,b, 2010Baroň et al, 2011;Pánek et al, 2011aPánek et al, , 2013 on the age and recurrence of thirteen large Holocene and recent CFLLs in the western Flysch Belt of the Outer Western Carpathians ( Fig. 1; Table 1).…”

“…Our dataset (25 dated landslide events) is too limited for chronological determinations, but it shows a possible correlation with other central-European paleoclimatological proxy records, including lake-level high stands (Magny, 2004), δ 18 O speleothem records Figure 8. Dating of individual CFLLs and their reactivations compared to probability density curve of Holocene dated landslide events in the Czech and Polish part of the Outer Western Carpathians and other central-European paleoclimatological proxy records: (1) single dates of studied CFLLs (median ± 1σ), 25 dates (this study; Baroň, 2007;Klimeš et al, 2009;Pánek et al, 2009aPánek et al, ,b, 2010Baroň et al, 2011;Pánek et al, 2011aPánek et al, , 2013; (2) normalised probability density curve of the Czech and Polish landslide events, 85 dates (Alexandrowicz and Alexandrowicz, 1999;Margielewski, 2006a;Baroň, 2007;Margielewski et al, 2010Margielewski et al, , 2011; (3) normalised probability density curve of the hydrological events in Polish rivers, 331 dates (Starkel et al, 2006); (4) advances of Alpine glaciers (by various authors in Starkel et al, 2006); (5) mid-European higher lake-level phases (Magny, 2004); (6) δ 18 O record from stalagmites AH-1 and (7) B7-7 in Sauerland/Germany (Niggemann et al, 2003). (Niggemann et al, 2003), Alpine glacial advances (various authors in Starkel et al, 2006), paleofloods (Notebaert and Verstraeten, 2010;Starkel et al, 2006) and timing of other landslides from the Czech and Polish flysch Carpathians (Baroň et al, 2004;Margielewski, 2006a;Margielewski et al, 2011) (Fig.…”

Past testate amoeba communities in landslide mountain fens (Polish Carpathians): The relationship between shell types and sediment

“…They are often hard to sample because of their location and complex lithology, that is, common presence of mineral layers and wood in peat (Margielewski, 2006a, 2018). Landslide fens have mainly been used as archives of past vegetation changes (Czerwiński et al, 2020; Kołaczek et al, 2020; Margielewski, 2006a; Margielewski et al, 2010; Michczyński et al, 2013; Pánek et al, 2012), landslide activity and geomorphological changes (Margielewski, 2018; Margielewski et al, 2011; Pánek et al, 2013), while testate amoebae have been investigated from a single site which was a poor fen (Šímová et al, 2019).…”