Zróżnicowanie facjalne glin jako wskaźnik fluktuacji ciśnienia wód subglacjalnych na kontakcie lodu i podłoża podczas zlodowacenia wisły w północnej części Pojezierza Dobrzyńskiego

Abstract

Sedimentological analyses were performed on glacial till of the Weichselian glaciation in two field sites (Przeszkoda and Oborki) which are located in northern part of the Dobrzyn Lakeland. During the last glaciation this area was covered by the Vistula ice lobe which development has been determined by the Vistula Ice Stream. A multi-proxy approach including a study of sedimentary features, grain size, petrographic composition, till fabric and till micromorphology was used in reconstruction of till formation and ice movement mechanisms. Analysed tills are massive and stratified. We suggest existing of complex and temporally variable conditions under the Vistula ice lobe, probably caused by subglacial water fluctuations. Ice movement was caused by a combination of bed deformation and basal sliding.