Record details

    Eclogites from the Czech part of the Erzgebirge: multi-stage metamorphic and structural evolution
Statement of responsibility
    Helena Klápová, Jiří Konopásek, Karel Schulmann
    Klápová, Helena
    Konopásek, Jiří
    Schulmann, Karel
Source title - serial
    Journal of the Geological society
    Vol. 155, no. 3
    p. 567-583
    11 obr., 1 fot., 4 tab., 3 s.bibl.
    Zkr. název ser.: J. Geol. Soc. (Oxford)
Subject group
    geologie strukturní
    krušnohorské krystalinikum
    metamorfóza vysokostupňová
    minerály horninotvorné
    podmínky P-T
    vrásnění variské
    zóna střižná
Geographical name
    Vykmanov (Chomutov)
Abstract (in english)
   A structural and petrological study of Saxothuringian eclogites in the central Erzgebirge, Czech Republic, revealed their polyphase thermal and tectonic evolution. The first stage of deformation is related to elogite-facies metamorphism of mafic rocks at pressures of 26kbar and temperatures of 650-700°C. The clinopyroxene crystallographic preferred orientation is consistent with high-temperature flow. The second stage of deformation is characterized by transport of eclogitic rocks at the base of acrustal nappe and their large-scale folding. During this stage, HP-HT metamorphic assemblages developed in the surrounding metapelites (14.5 kbar/600°C) while eclogite assemblages were preserved in passively transported eclogitic boundins. Heat advection and similar P-T conditions in the surrounding crustal material are responsible for the stability of mineral assemblages and preclude closure of isotopic systems in the eclogites.
   Therefore the published isotopic ages of the eclogites do not reflect the subduction stage but the age of cooling under crustal conditions, Subsequent large-scale (D3) folding is responsible for reorientation of previously flat-lying earlier fabrics (D1-D2). The final stage of deformation is marked by the development of a heterogenous network of ductile retrograde shear zones. The thermometry and geochemical study of amphibolitized eclogites in the cores of shear zones indicates thermal conditions not exceeding those in surrounding metapelites and fluid influx. The fluid influx is interpreted to be the result of water-producing prograde reactions in the footwall metasediments and fluid chanelling into the base of the nappe during brittle deformation of the eclogites
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
Entered date
    21. 3. 2008
Import date
    8. 8. 2012