Podrobnosti záznamu

    Microstructural and metamorphic evolution of a high-pressure granitic orthogneiss during continental subduction (Orlica-Snieznik dome, Bohemian Massif)
    Chopin, F.
    Lexa, Ondrej
    Martelat, J. E.
    Petri, B.
    Pitra, P.
    Schulmann, K.
    Štípská, P.
Typ dokumentu
    článek v periodiku
Zdrojový dokument - seriál
    Journal of Metamorphic Geology
    Roč. 30, č. 4
Výraz tezauru
    crust rheology
    eclogite granitic orthogneiss
    European Variscan belt
    petrological modelling
    quantitative microstructural analysis
Klíčové slovo
Abstrakt (anglicky)
   A microstructural and metamorphic study of a naturally deformed medium- to high-pressure granitic orthogneiss (OrlicaSnieznik dome, Bohemian Massif) provides evidence of behaviour of the felsic crust during progressive burial along a subduction-type apparent thermal gradient. The granitic orthogneisses develops three distinct microstructural types, as follows: type I augen orthogneiss, type II banded orthogneiss and type III mylonitic orthogneiss, each representing an evolutionary stage of a progressively deformed granite. Type I orthogneiss is composed of partially recrystallized K-feldspar porphyroclasts surrounded by wide fronts of myrmekite, fully recrystallized quartz aggregates and interconnected monomineralic layers of recrystallized plagioclase. Compositional layering in the type II orthogneiss is defined by plagioclase- and K-feldspar-rich layers, both of which show an increasing proportion of interstitial minerals, as well as the deformation of recrystallized myrmekite fronts
   . Type III orthogneiss shows relicts of quartz and K-feldspar ribbons preserved in a fine-grained polymineralic matrix. All three types have the same assemblage, but show systematic variations in the composition of muscovite and garnet from types I to III. This is consistent with the equilibration of the three types at different positions along a prograde P-T path ranging from <15 kbar and <700 degrees C (type I orthogneiss) to 19-20 kbar and >700 degrees C (types II and III orthogneisses). The deformation types thus do not represent evolutionary stages of a highly partitioned deformation at constant P-T conditions, but reflect progressive formation during the burial of the continental crust. The potential role of incipient melting in strain localization is discussed.
    UK Praha, Přírodovědecká fakulta
Kód přispěvatele
    UK, PřF
Zdrojový formát
Datum importu
    27. 4. 2014