Zagadnienie waryscyjskiej przebudowy NE obrzeżenia Masywu Czeskiego

Abstract

ON VARISCAN RECONSTRUCTION OF NE MARGIN OR THE BOHEMIAN MASSIF Summary The Sudety Mts and Fore-Sudetic block represent north-eastern margin of the Bohemian massif (Fig. 1). Here occur structural elements connected with various orogenes. The Sowie Mts gneisses are considered as the Moldanubian. Alterated rooks of amphibolite facies are usually related to the Cadomian (Assinthian) orogeny. Weakly metamorphosed phyllites and greenstones, known as the epimetamorphic series of the Kaczawskie Mts and previously interpreted as Caledonian complex, are at present usually assigned to the Variscides. There is no equivocal evidence for the Proterozoic age of the metamorphosed rocks of amphibolite facies. Mesoscopic structures displayed by these rocks indicate that the series interpreted as Cadomian complex underwent complete alteration in result of the Variscan movements. The methamorphosed rocks of amphibolite facies occur at the same intersection level as weakly metamorphosed phyllites and greenstones. This means that the heavily metamorphosed series represent an elevated part at the Earth crust. Within the Fore-Sudetic block rocks of that series form an arch bent towards the north-east. Eugeosynclinal rocks of the Kaczawskie Mts, folded and weakly metamorphosed at the turn of the Devonian and Carboniferous, occur inside that arch, and Lower Carboniferous developed in flysch facies - on the external side of that arch (see Fig. 2). This arch is interpreted as geoanticlinal zone separating the internal (Saxo-Thuringian zone) and external (Rhine-Hartz) zones of the Variscan orogen. Faults running along this geoanticlinal zone deeply cut the Earth crust down to the Moho surface. The structure described above is situated at the extension of Central-German crystalline zone (Fig. 3) for which the name of Central-European crystalline zone seems more appropriate.