Thermal basal regime of the Elsterian ice‐sheet marginal zone in a hilly mountain foreland, Rychleby Mts., Eastern Sudetes

• Published in: Boreas
• Main Authors: Hanáček, Martin, Nývlt, Daniel, Jennings, Stephen J. A.
• Other Authors: Masarykova Univerzita
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: Geology; Archeology; Ecology, Evolution, Behavior and Systematics; Rugged Mountain; Ice; Ice Sheet; permafrost
• Online Access: http://dx.doi.org/10.1111/bor.12505; https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12505; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/bor.12505

The Scandinavian Ice Sheet reached the Sudetes and Carpathian Mountains during the Elsterian glaciation. A long ice‐sheet piedmont marginal zone affected by the rugged mountain foreland topography and associated slopes originated. This study focuses on the hilly Rychleby Mts. foreland (Eastern Sudetes, Czechia), which was a part of the piedmont marginal foreland zone of the ice sheet. The basal regime was reconstructed through an investigation of the sedimentology, structural features, and the nature of ice‐sheet erosion of preglacial landscapes evident at two sites located ~3–5 km inside the maximum ice‐sheet extent. These sites show a preglacial relief buried by sub‐ to supraglacial sediments. The sites were located under an ice cover of max. 200 m. Evidence of cold‐based conditions (including palaeotors with delicate structures on the bedrock, almost absent striations on clasts, originally frozen unlithified sedimentary rafts) exists at both sites. Permafrost composed of coarse‐grained sediments was subject to brittle deformation at the base of the ice sheet, whereas permafrost composed of fine‐grained sediments underwent ductile deformation. The margin of the Scandinavian Ice Sheet in the Rychleby Mts. foreland was cold‐based, therefore glacial erosion was not sufficient to significantly remodel the palaeotors into roches moutonnées. During ice‐sheet decay, the preglacial landscape was partially buried by melt‐out tills and meltwater sediments.