Browsing by Author "Rachleiwcz, Grzegorz"
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Item Ice tectonics and bedrock relief control on glacial sedimentation – an example from Hansbreen, Spitsbergen(Pracownia Sztuk Plastycznych Sp. z o.o., 2000) Rachleiwcz, Grzegorz; Szczuciński, WitoldHansbreen, a tidewater glacier in southern Spitsbergen, was investigated to reveal the relationship between its tectonic and mode of deposition. In the land terminating zone the bedrock threshold plays major role in sedimentation by creating compression conditions. It causes the most of sediment to be released supraglacially, and redeposited in form of debris flows. The upward debris transport is done mostly by folding deformation of basal ice layer with a minor participation of thrusts. In observed outcrops no subglacial deformed layer of till was found. The debris occurrence was associated only with the debris-rich basal ice layer. However on the foreland exists subglacial till, partly formed in flutings, also with micromorphological evidence of deformations. Various bedrock morphology is supposed to differentiate basal conditions. The flat, but undulated, regelation favouring conditions, leads to the debris-rich basal ice layer formation, however inclined but non undulated relief prefers deformed subglacial sediments development. No structural or sedimentological evidence of surge events were found in the tributary glaciers (Fuglebreen, Tuvbreen), hence this phenomenon is thought to be limited to the main ice stream.