Z tektoniki Podkarpacia w okolicach Krakowa

Abstract

NOTES ON THE CRACOW SUB-CARPATHIAN TECTONICS . 311 Summary In Southern Poland, the Podkarpacie (Sub-Carpathian) zone streches as a relatively narrow belt along the margin of the Carpathian Flysh overthrust. It has been known since the Middle Ages as the place of occurrence of salt brines, rock salt (Bochnia and Wieliczka mines) and gypsum as well as sulphur in exceptional cases. The Miocene (Badenian) salt-bearing formation occurs in the zone, filling up the Podkarpacie foredeep with the big mass of clayey sediments. The evaporite horizon in the stratigraphic column of this formation has been considered the best key-member. The compiled transversal cross- sections give support to the hitherto accepted major features of the tectonics of the Podkarpacie zone: l) large-scale thrust of marginal Flysh units in the form of a nappe over the salt-bearing formation; 2) overthrust and steep folding of strata of this formation in south; and 3) overthrust of the folded strata of the formation on the undisturbed autochtonous cover. The formation rests there directly on the Mesozoic platform of the Carpathian foreland (Jurassic, Cretaceous). Mesozoic rocks are underlain by those of Variscan Paleozoic complex (Devonian, Carboniferous and Permian) of large thickness situated in the foreland of an ancient mountain range - the Cracovides. The Cracow Sub-Carpathian is limited to the zone egment, 25 km long and about 7 km wide (fig. 1). The structural distinctness of the segment results from the Mesozoic platform uplift where transcending across the main Cracovides anticline. The Variscan complex there represents a cover of a still older tectonic complex, built of Cambrian, Ordovician and Silurian strata deformed in some polyphases of the Caledonian orogeny and forming the main Cracow anticline nucleus. The most characteristic secondary features of the Cracow Sub-Carpathian tectonics have been reflected by the structural disturbances of the Miocene salt-bearing evaporite key-member on the cross-sections (fig. 2). Important detail - an overturned fold passing into a tectonic scale. However, the Mesozoic platform behaved in quite a rigid way under the influence of -tangential stresses, which resulted in its compresional dismembering and faulting.