Record details

Title
    The mid-European segment of the Variscides: tectonostratigraphic units, terrane boundaries and plate tectonic evolution
Statement of responsibility
    Wolfgang Franke
Other titles
    Orogenic Processes: Quantification and Modelling in the Variscan Belt (Variant.)
Author
    Franke, Wolfgang
Language
    anglicky
Source title - serial
    Geological society special publication
Vol./nr.
    Vol. 179
Pages
    p. 35-61
Year
    2000
Notes
    9 obr., 1 tab., 9 s.bibl.
    Zkr. název ser.: Geol. Soc. spec. Publ. (London).
Subject group
    autochton
    bohemikum
    datování U/Pb
    devon
    granitoidy
    kolize desek
    metamorfika
    metamorfóza
    moldanubikum
    saxothuringikum
    silur
    tektonika desková
    terán
    vrásnění variské
Geographical name
    Česká republika
    SRN
Keyword
    Boundaries
    Evolution
    Mid-European
    Plate
    Segment
    Tectonic
    Tectonostratigraphic
    Terrane
    Units
    Variscides
Abstract (in english)
   The mid-European segment of the Variscides is a tectonic collage consisting of (from north to south): Avalonia, a Silurian-early Devonian magmatic rc, members of the Armorican Terrane Assemblage (ATA: Franconia, Saxo-Thuringia, Bohemia) and Moldanubia (another member of the ATA or part of N Gondwana?). The evolution on the northern flank of the Variscides is complex. Narrowing of the Rheic Ocean between Avalonia and the ATA occurred during the late Ordovician through early Emsian, and was accompanied by formation of an oceanic island arc. By the early Emsian, the passive margin of Avalonia, the island arc and some northern part of the ATA were closely juxtaposed, but there is no tectonometamorphic evidence of collision. Renewed extension in late Emsian time created narrow Rheno-Hercynian Ocean whose trace is preserved in South Cornwall and at the southern margins of the Rhenish Massif and Harz Mts.
   Opening of this successor ocean to the Rheic left Armorican fragments stranded on the northern shore. These were later carried at the base of thrust sheets over the Avalonian foreland. Closure of the Rheno-Hercynian Ocean in earliest Carboniferous time was followed by deformation of the foreland sequences during the late lower Carboniferous to Westphalian. Closure of narrow oceanic realms on both sides of Bohemia occurred during the mid- and late Devonian by bilateral subduction under the Bohemian microplate. In both these belts (Saxo-Thuringian, Modanubian), continental lithosphere was subducted to asthenospheric depths, and late Devonian to the late lower Carboniferous in a regime of dextral transpression. The orthogonal component of intra-continental shortening produced an anti-parallel pair of lithospheric mantle slabs which probably joined under the zone of structural parting and became detached.
   This allowed the ascent of asthenospheric material, with important thermal and rheological consequences
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    30. 4. 2007
Import date
    8. 8. 2012