DEFORMACJE GLACITEKTONICZNE I ICH WPŁYW NA ROZWÓJ PALEOGEOGRAFII ŚRODKOWOZACHODNIEJ POLSKI (REJON ZIELONEJ GÓRY)

Abstract

GLACIOTECTONIC DEFORMATIONS IN CENTRALWESTERN POLAND (ZIELONA GÓRA REGION) AND THEIR INFLUENCE ON EVOLUTION OF PALAEOGEOGRAPHY

Abstract. Numerous glaciotectonic structures have been recognized in the Zielona Góra region (centralwestern Poland). Glaciotectonic deformation zones have been identified by geomorphological analysis, comparison of borehole sections, studies of drill cores of cartographical boreholes, geophysical surveys, and measurements and observations in outcrops. In this area, thrust moraines deposits are outcropped on the land surface. Palaeolandforms - glacial elevations and depressions - are covered by undeformed sediments. The Zielona Góra Rampart is the area of investigation of glaciotectonic deformations where different glaciotectonic models have been verified. Glaciotectonic data, collected by the author, and his personal investigations show the great significance of thrusts within the geological structure of the Zielona Góra Rampart. A model of cylindrical shears (Rotnicki, 1976) was used for interpreting the origin of the Zielona Góra Rampart. The use of this model is additionally suggested by the fact that the macrostructures occur in series, and uplifted landforms are separated by glaciotectonic depressions. Glaciotectonic deformations developed mainly as a result of stress within the subglacial bedrock, generated by the load of the glacier. Lateral compression of the glacier did not play an important role in the formation of mega-scale deformation. Results of lithostratigraphic studies of tills and stratigraphical data indicate that the major glaciotectonic zones formed during the Elsterian (Dyjor, 1975; Urbański, 2002 a) but in some regions glaciotectonic deformation processes also occurred during the transgressive phase of the Odranian Glaciation. It was a phase of modifications within deformation zones formed during the South Polish Glaciations. Land surface topography, developed as an effect of glaciotectonic deformations, exerted a great influence on subsequent, Late Pleistocene geological processes. In the area of Dalkowskie Hills, the main stage of deformations took place in the Sanian (Badura, Przybylski, 2002). Thick glaciolacustrine series were deposited in glaciotectonic depressions. During the Warthanian Glaciations, the ice sheet stopped at the Dalkowskie Hills. During the Vistulian Glaciation, the ice sheet was blocked by the Zielona Góra Rampart stretching across the glacier movement direction. Kame terraces developed on northern slopes of this structure at that time.