Podrobnosti záznamu

    Variscan orogeny in Bohemian Massif and French Massif Central: differences and similarities
    Edel, Jean-Bernard
    Faure, Michel
    Janoušek, Vojtěch
    Lardeaux, Jean-Marc
    Lexa, Ondrej
    Schulmann, Karel
    Štípská, Pavla
Typ dokumentu
    článek ve sborníku
Zdrojový dokument - monografie
    Géologie de la France
    Akce: 2012 ; Sassari
Výraz tezauru
    Variscan Orogen, Bohemian Massif, Massif Central
Klíčové slovo
Abstrakt (anglicky)
   Following are main similarities and differences between the Bohemian Massif and the French Massif Central: Crustal-scale geometry and orogenic architecture: in the BM the lower crust is composed of 10 km thick felsic layer situated beneath a mafic one. The BM is a supra-subduction orogen of double crustal thickness mainly derived from the Upper plate, except for exhumed felsic orogenic lower crust, which comes from the Lower plate. In contrast, the current lower crust of the FMC consists of a layered mafic crust (gabbros, mafic granulites and minor felsic granulites) located beneath a stack of mainly felsic units. The FMC architecture is derived from both Upper and Lower plates. Subduction processes: in the BM these were marked by 60 m.y. lasting continuous SE-dipping subduction leading to the formation of blueschist-facies rocks with A, B and C-types of eclogites and significant arc magmatism. In contrast, the FMC reveals B-type eclogites and discontinuous arc magmatism related to a p
   olyphase subduction, initially North-dipping (early closure of the MC Ocean) followed by Devonian to Carboniferous South-dipping subduction. Continental underthrusting: underthrusting of felsic radioactive Saxothuringian crust in the BM lead to the development of laterally-forced gravity overturns and exhumation of orogenic lower crust while in the FMC the mechanism consisted in northward underthrusting of Gondwanan crust associated with crustal-scale folding of stacked units. Late Variscan tectono-thermal reworking: associated in the BM with production of Late Carboniferous (330-300 Ma) post-tectonic to syn-collisional granites while in the FMC the thermal reworking was much more important. It was accompanied by syn- and post-thickening extension leading in the LGU to the emplacement of Late Carboniferous to Early Permian granite/migmatitic domes contemporaneous with sedimentary basin development at upper crustal levels. The latter was associated with extensional tectonics.
    Česká geologická služba
Kód přispěvatele
    ČGS (RIV)
Zdrojový formát
Datum importu
    15. 10. 2014