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Development of a non-perennial to ephemeral fluvial system in continental fault-bounded basin – an example from the early Permian Krajanów Formation of the Intra-Sudetic Basin (NE Bohemian Massif)

Kowalski Aleksander, Furca Magdalena

Geological Quarterly

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2023

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Vol. 67, No. 3

art. no. 31

EN

Non-perennial to ephemeral fluvial systems dominated by seasonal discharge fluctuations and episodic rapid flood-flow events are typical of arid to semi-arid climatic conditions. Dryland fluvial systems have been described from many ancient and modern, predominantly tectonically-controlled sedimentary basins across the globe. This study provides detailed sedimentological analysis and palaeoenvironmental interpretation of the lowermost part of the early Permian (?Asselian) Krajanów Formation exposed within the continental, fault-bounded Intra-Sudetic Basin (ISB), located on the NE periphery of Bohemian Massif. High-resolution sedimentological logging and facies analysis indicate that the early Permian fluvial system in this area was dominated by ephemeral fluvial processes influenced strongly by a semi-arid to arid climate. Rapid (?catastrophic) flood events led to episodic sedimentation of vertically and laterally amalgamated fluvial channel infills, with abundant upper flow regime structures as well as poorly channelized, laterally extensive sheet-like bodies of sandstone. The overbank deposits are poorly preserved due to frequent lateral shifting of the channels. Soft-sediment deformation structures formed due to events of river bank collapse as well as debris flow facies point to high-energy, waning flows. It is concluded that deposition occurred on broad, terminal-type alluvial fans, probably in their proximal- to medial segments within a distributive fluvial system of the Permian Intra-Sudetic Basin. Petrographic composition and measured palaeocurrent directions show that the sediment was sourced from the neighbouring massifs – the Sowie Mts. Massif to the east, the Bardo Structure and a hypothetical Southern Massif to the south/south-east.

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Palaeogeographic reconstruction of the North Podlasie region in the Sokółka area during the Late Pleistocene (NE Poland)

Rychel Joanna

Geological Quarterly

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2021

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Vol. 65, No. 1

art. no. 12

EN

A new palaeogeographic reconstruction from the end of the Odranian Glaciation to the end of the Weichslian Glaciation (MIS 2) is based on research carried out at the Knyszewicze site, NE Poland, focusing on the dynamics of the Wartanian Glaciation (MIS 6) and showing the lobed nature of this ice sheet. Reconstruction of deglaciation in the research area was supplemented by analysis of postglacial morpholineaments (MMA). Research carried out at the Jałówka site enabled reconstruction of the processes affecting lake processes during the Eemian (MIS 5e) Interglacial and transformation of this area during the Weichselian Glaciation. The results obtained indicated that the study area was not covered by Weichselian ice, the sediments formerly considered as glacial being slope-related and providing evidence of periglacial conditions. A new conceptual model for the evolution of this area is put forward, showing the polygenetic nature of the relief. The glacial landforms developed during the Warta Stadial and transformed during the Eemian Interglacial were further affected by periglacial processes, which significantly remodelled the relief.

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Osady deglacjacyjne zlodowacenia Warty we wschodniej części regionu łódzkiego

Rdzany Z.

Przegląd Geologiczny

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2006

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Vol. 54, nr 4

343-351

EN

The author attempts at formulating a synthetic description of geological and geomorphological effects of theWartanian ice-sheet deglaciation in the eastern part of the Łódź region, taking their spatial variability into consideration. Characteristic features of Wartanian Glaciation sediments occur in this area, and their lithofacial diversity and spatial distribution needed interpretation. The deposits document the complex processes of deglaciation, which developed here across an unusually broad area in the scale of the Polish Lowland. The best developed deglaciation sediments occur in the eastern part of the Łódź Heights, between the Mroga and Rawka rivers, as structural components of different types of kames and glaciofluvial covers. In locations where glacial till is elevated they include mainly sediments of braided rivers and alluvial cones, whereas in areas of wide depressions of till and, thus, of the ice-sheet bedrock — glaciolimnic sediments prevail. The highest and most diverse western part of the Łódź Heights is characterised by the occurrence of thin and discontinuous deglaciation sediments, because this area was shaped mainly during the ice-sheet transgression. During deglaciation, ablation waters left mainly traces of erosion, whereas the glaciofluvial accumulation series are not well developed. In the Rawa Interfluve, deglaciation sediments accumulated predominantly at the early deglaciation stage in sparesely distributed broad basins of kame sedimentation. In the Piotrków Plain, deglaciation deposits are thin; ice-sheet disintegration proceeded without major blockages of ablation waters, resulting in a less diverse interfluvial landscape.