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Structural and textural response to dynamics of fluvioglacial processes of the Rzymsko esker sediments, Central Poland

Frydrych M.

Geology, Geophysics and Environment

2016

Vol. 42, no. 4

411--428

The study was conducted in the Rzymsko esker, in the Eastern part of the Turek Upland Plain, within the range of the Warta Glaciation (Saalian II). The form was accumulated in a tunnel valley, which was partially filled with esker sediments. Lithofacies analysis, extended by a detailed analysis of clasts, made it possible to identify a considerable variability of sedimentation conditions. At the initial stage, transport and accumulation of sediments took place in the conditions of high energy hydraulic flows or hyperconcentrated flows. The flow energy rose cyclically, which was recorded as sediments coarsening. Deposits of boulders as well as massive and cross-bedded gravels were identified, a record of catastrophic glacial floods. During the later stage of esker formation, sandy and gravelly sediments were accumulated in an open crevasse. The strong erosional force of subglacial water is confirmed by an extremely high content of local rocks in the gravelly fraction (30–87%) and its very good roundness. Zingg shape analysis (1935) revealed a clear predominance of oblate forms among local clasts and equant fennoscandian erratics. A dependency was also found between the processing method and petrographic characteristics.

Texture and petrography of glacial deposits in the northern foothill of the Hruby Jesenik and Rychlebske Mts., Czechia

Sikorova J., Višek J., Nyvlt D.

Geological Quarterly

2006

Vol. 50, No. 3

345-352

The petrographic and mineralogical characteristics of glacial deposits from the localities in the northern foothills of the Hruby Jesenik and Rychlebske Mts. have been studied. Grain-size, petrographic composition, heavy minerals, clast shape and roundness have been investigated. The data obtained have been used to create a probability model to differentiate the stratigraphy of particular accumulations and for partial reconstruction of the advance direction of the ice sheet in the area. The main advance direction of the ice sheet was presumed to be from the NW to SE in this region. The erratic material was probably predominantly transported in the basal ice layers according to the clast shape and roundness. An Elsterian age of the sedimentary bodies investigated is suggested by correlation with analogous deposits in adjacent parts of Poland. This model contradicts previous correlations. However, further constraints on the stratigraphic position of these deposits would require the application of dating techniques.