Główne etapy ewolucji tektogenu waryscyjskiego Polski w świetle teorii tektoniki płyt
Abstract
MAIN STAGES IN EVOLUTION OF POLISH VARISCAN TECTOGEN IN THE LIGHT OF THE PLATE TECTONICS
Summary
The paper is aimed at drawing attention to the possibility of a new, dynamic look on evolution of Polish Variscides and interpretation of this orogeny from the plate tectonics viewpoint. Middle-European Variscan geosyncline originated in the Eocambrian in result of break up of the old Precambrian continent into several microcontinents of the Bohemian massif type. The Bohemian massif shifted far from the East-European platform between the Eocambrian and Ordvician in result of sea floor spreading. The shift led to formation of the Atlantic type margins on opposite sides of the resulting basin. The sedimentary basin of Polish Variscides several times changed its width and depth in result of overlapping effects of spreading and subduction, progressively decreasing in size towards the end of the Paleozoic. The paleomagnetic studies evidence that in the Carboniferous and Permian the sialic masses of the Bohemian massif and East-European platform were approaching one another and finally collided. In this way orogeny of the cordilleran (6), i.e. Andine (14, 24) type originated in the Saxo-Thuringian zone. This zone is characterized by low- and medium-pressure regional metamorphism (12) and intensive acid volcanism and plutonism, so it may be interpreted as Variscan internides (17). The part of Polish Variscides situated north of Sudety Mts and at present forming Paleozoic platform sockle is characterized by much weaker development of endogenic processes and represents so-called Variscan externides finally folded in the Late Carboniferous (17, 23). The Variscan molasses originated in the foreland and partly in the Sudety Mts in the Late Carboniferous and Early Permian.
Summary
The paper is aimed at drawing attention to the possibility of a new, dynamic look on evolution of Polish Variscides and interpretation of this orogeny from the plate tectonics viewpoint. Middle-European Variscan geosyncline originated in the Eocambrian in result of break up of the old Precambrian continent into several microcontinents of the Bohemian massif type. The Bohemian massif shifted far from the East-European platform between the Eocambrian and Ordvician in result of sea floor spreading. The shift led to formation of the Atlantic type margins on opposite sides of the resulting basin. The sedimentary basin of Polish Variscides several times changed its width and depth in result of overlapping effects of spreading and subduction, progressively decreasing in size towards the end of the Paleozoic. The paleomagnetic studies evidence that in the Carboniferous and Permian the sialic masses of the Bohemian massif and East-European platform were approaching one another and finally collided. In this way orogeny of the cordilleran (6), i.e. Andine (14, 24) type originated in the Saxo-Thuringian zone. This zone is characterized by low- and medium-pressure regional metamorphism (12) and intensive acid volcanism and plutonism, so it may be interpreted as Variscan internides (17). The part of Polish Variscides situated north of Sudety Mts and at present forming Paleozoic platform sockle is characterized by much weaker development of endogenic processes and represents so-called Variscan externides finally folded in the Late Carboniferous (17, 23). The Variscan molasses originated in the foreland and partly in the Sudety Mts in the Late Carboniferous and Early Permian.