Sedimentary Record of the Younger Saalian Ice Margin Stagnation in Eastern Poland: Development of a Regular Pattern of Glaciolacustrine Kames |
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| Authors: | Beata Gruszka S?awomir Terpi?owski |
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| Institution: | 1. Institute of Geology, Adam Mickiewicz University, Poznań, Poland;2. Department of Geoecology and Paleogeography, Maria Curie‐Sk?odowska University, Lublin, Poland |
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| Abstract: | Glaciolacustrine kames in the Bielsk Podlaski area (eastern Poland) exhibit a unique regular pattern. Three representative morphological kame types were chosen for detailed sedimentological analyses, specifically: isolated, isometric mounds; isolated, elongated hills; and branching ridges. All types comprised fine‐grained sandy and sandy/silty deposits. Lithofacies analysis resulted in the distinction of several lithofacies associations. Associations dominated by medium‐ or large‐scale, massive or horizontally laminated sands are interpreted as proximal subaqueous fans; associations dominated by medium‐ or small‐scale lithofacies of ripple‐drift cross‐laminated sand are interpreted as distal subaqueous fans; and those dominated by sandy/silty, silty or silty/clayey lithofacies with horizontal lamination are interpreted as lake bottomsets. Rates of sediment accumulation appear to have been fast, resulting in syndepositional and metadepositional deformation structures of two types: water‐escape structures, and slumps on subaqueous slopes. After the ice‐walled lake basins filled with sediment, glaciofluvial erosion and deposition alternated, resulting in erosional channels of up to 1 m deep, later filled with gravel or gravely sand. The results indicate that kames developed in a supraglacial environment within a topography of ice‐cored moraines containing ice‐walled lakes that persisted due to the presence of permafrost. Pauses during retreat of the ice walls resulted in ice‐contact deformations at the edges of the kames. Kame formation is therefore consistent with a continental climate and this may explain the increased abundance of this type of kame system in Eastern Europe. |
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| Keywords: | kames supraglacial landsystem ice‐cored moraine topography climate continentality Poland |
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