Płaszczowina magurska i jej podłoże na północ od Kotliny Sądeckiej

Marek Cieszkowski



This paper summarizes the results of geological studies (12, 13, 14, 9, 23) recently carried out in the Magura Nappe and the other structural units (thrust sheets) of the Outer Carpathians in north-eastern part of the Beskid Wyspowy Mts. and the Rożnów Foothills (Fig. 1). The Magura Nappe is thrust here upon units of the fore-Magura zone sensu Książkiewicz (18), represented by the southern and northern Grybów Units, and Michalczowa Zone (9). All these units, in turn, are further thrust together on the Silesian Nappe, Sub-Silesian Unit (cropped out in tectonic windows of Lanckorona - Żegocina structural zone), and on the transgressive Miocene deposits. The lithostratigraphic sections of the Outer Carpathians units is shown in Fig. 2. In southern part of the area studied, the tectonic window of KIęczany - Limanowa reveals folded and thrust rocks of the Grybów Unit (Fig. 1). From beneath these rocks, Cretaceous sequence crops out in the Kurów tectonic window. This sequence has until now been assigned to the Silesian Nappe (27, 19, 20). It may represent Cretaceous deposits of the northern Grybów Unit. The Magura Nappe is composed of a series of tight anticlines, separated by relatively broad anticlines. The border thrust of this nappe between Wojakowa and Łęka recedes southward by 14 km. The area in question is also cut by several systems of transversal, longitudinal and oblique faults (Fig. 1, 3). Recent structural position of the Outer Carpathian Units thrust upon the transgressive Miocene deposits at Iwkowa (Figs. 1,3), as well as the age and composition of conglomerates that interbed the Bela and Iwkowa Formations (9, 12, 13), enable one to reconstruct the last stage of folding and thrusting of the Magura Nappe and Fore-Magura zone units (Fig. 4). In this stage, the amplitude of horizontal motions during Late Badenian and Early Sarmatian times ranged from several kilometers, to more than 10 km in case of the Magura Nappe.