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An examination of the glaciomarginal fan of the Odranian glaciation at the Mokrzeszów site, Sudetic Foreland, SW Poland

Krzyszkowski Dariusz, Wachecka-Kotkowska Lucyna, Skurzyński Jacek

Geology, Geophysics and Environment

2022

Vol. 48, no. 3

287--318

The article presents the results of research from the Mokrzeszów site in the Sudetic Foreland. Lithopetrographic and sedimentological analyses of sediments from the Middle Polish Glaciations (Early Saalian, Odranian, MIS6) in this area indicate the overrepresentation (90–95%) of large Scandinavian erratics. The deposits, representing a repetitive sequence of Gp-Gms-Sp-Sh/Sr(Dmm) lithofacies, accumulated during at least two episodes of glacial outburst floods and six sedimentary cycles. High-energy flows are estimated for the Gms and Gp facies at about 5 m∙s−1 and low-energy flows indicate 0.8 m∙s−1 for the Sp/Sh/Sr facies, to the lack of flow (Fm). The sedimentary sequences confirm the existence of a fan, which may have originated as a subaqueous steep coarse-grained fan in glacial-flow-lake-outburst floods that formed between the ice sheet front and the morphotectonic edge of the Sudetic Marginal Fault line and within the Roztoka-Mokrzeszów Graben, or as an aerial, piedmont fan on the Sudetic Marginal Fault edge. The sediments show discontinuous deformations – gently sloping faults and fractures from glacioisostatic stresses. The fault activity is probably related to the reactivation of the faults due to ice loading during or after the older Saalian glaciation.

Chronostratigraphy of Late Glacial aeolian activity in SW Poland – A case study from the Niemodlin Plateau

Moska Piotr, Jary Zdzisław, Sokołowski Robert Jan, Poręba Grzegorz, Raczyk Jerzy, Krawczyk Marcin, Skurzyński Jacek, Zieliński Paweł, Michczyński Adam, Tudyka Konrad, Adamiec Grzegorz, Piotrowska Natalia, Pawełczyk Fatima, Łopuch Michał, Szymak Agnieszka, Ryzner Kamila

Geochronometria

2020

Vol. 47, no.1

124--137

The stratigraphy of Late Pleniglacial and Late Glacial fluvio-to-aeolian succession was investigated in two sites located at the Niemodlin Plateau, SW Poland. Lithofacial analysis was used for the reconstruction of sedimentary environments. An absolute chronology for climatic change and the resulting environmental changes were determined based on optically stimulated luminescence (OSL – nine samples) and radiocarbon (three samples) dating methods. Four phases of changes in sedimentary environments were established. The first depositional phase correlates with the Last Permafrost Maximum (24−17 ka) based on the type and size of the periglacial structures, which aggraded under continuous permafrost conditions. During 17.5−15.5 ka (upper Late Pleniglacial), a stratigraphic gap was detected, owing to a break in the deposition on the interfluve area. The second depositional phase took place during 15.5−13.5 ka. During this phase, the first part of the dune formation (Przechód site) and fluvio-aeolian cover (Siedliska site) was deposited. The sedimentary processes continued throughout the entire Bølling interstadial and Older Dryas. In the third phase (Allerød interstadial), soil formation took place. At the Siedliska site, palaeosol represented Usselo soil type, whereas at the Przechód site, there was a colluvial type of soil. The last phase (Younger Dryas) is represented by the main phase of dune formation in both sites. After the Younger Dryas, no aeolian activity was detected. High compliance with both absolute dating methods was noticed.