North‐central Poland was originally shaped by the Płock lobe of the ice sheet formed during the Weichselian Glaciation. The majority of the studied area comprises the Dobrzyń Lakeland, where numerous terminal moraine hills preserve a record of recession of the ice sheet from the maximum extent of the last glaciation (LGM). Analysis of a digital elevation model enabled the determination of a network of morpholineaments, referring to the formation of linear glacial forms. Recession of the ice sheet from the LGM extent in north‐central Poland was uneven and proceeded in stages. Ice‐sheet recession stages were interspersed with local or regional ice‐sheet advance stages. During these individual periods of ice‐sheet behaviour, ice‐sheet movement changed direction from WNW–ESE to NNW–SSE. Transgression of the ice sheet into the central part of the study area as well as the Kujawy–Dobrzyń subphase may be related to cooling of the climate during 18.5–17.7 ka before ad 2000.
The analysis of low‐field anisotropy of magnetic susceptibility (AMS) was used to reconstruct the subglacial deposition conditions during the Main Stadial of the Odranian Glaciation (MIS 6) in till deposits from a site in Dębe (central Poland). Based on the AMS parameters, six till beds were identified (intervals 1–6). The declination of the maximum magnetic susceptibility axis (k1) indicates that the ice sheet was moving in from the northwest. The obtained results confirm the thesis about the preferred direction of ice‐sheet transgression during the Odranian Glaciation (MIS 6) in this part of Poland. This interpretation is also confirmed by data obtained from measurements of the long axis of clasts, which agree with the orientation of k1. Based on the AMS results, a significant part of the profile was deformed through simple shear and direct interaction of the ice sheet with the underlying sediment (beds 2–5). The lowest part of the till (bed 6) may have been deposited on a southeast‐trending slope or post‐depositional deformed by uneven loading of the ice cover. The upper part of the profile (especially in interval 1) could be deposited with an impact of pore water.
New microfossil and magnetostratigraphical data as well as geochemical and clay mineral weathering indices are documented from the uppermost Jurassic Owadów-Brzezinki palaeontological site in central Poland. The newly discovered chitinoidellid assemblage of the lowermost part of the section and the previously documented assemblage from the middle part of the section are assigned, respectively, to the uppermost Dobeni and Boneti subzones of the Chitinoidellidae Zone. The same part of the succession is correlated to the magnetosubzone M20n.2n. The new data allow refinement of the Tithonian stratigraphical scheme including an assignment of the upper part of the Boreal Zarajskites Subzone of the Scythicus (Panderi) ammonite Zone to the Upper Tithonian and its correlation with the lowermost part of Tethyan Microcanthum ammonite Zone and the lower portion of the M20n.2n magnetosubzone. The data show that the Fittoni/Albani ammonite zone boundary (constituting a boundary of the informal Bolonian and Portlandian stages) should likely be placed within the Boneti Subzone. The geochemical data show decreasing chemical weathering intensity during the earliest Late Tithonian in central Poland, which is linked to aridification of the latest Jurassic climate. The same trend is observed in coeval sections of NW and NE Europe.
Supplementary material:
https://doi.org/10.6084/m9.figshare.c.6299266
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