Record details

Title
    Formation and destabilization of the high pressure assemblage garnet-phengite-paragonite (Krušné hory Mountains, Bohemian Massif): The significance of the Tschermak substitution in the metamorphism of pelitic rocks
Statement of responsibility
    Jiří Konopásek
Author
    Konopásek, Jiří
Language
    anglicky
Source title - serial
    Lithos
Vol./nr.
    Vol. 42, no. 3-4
Pages
    p. 269-284
Year
    1998
Notes
    7 obr., 1 fot., 5 tab., 2 s.bibl.
    Zkr. název ser.: Lithos
Subject group
    granáty
    metamorfóza vysokotlaká
    metapelity
    podmínky P-T
    příkrov
    slídy
    substituce
    svor
    živce
Geographical name
    ČR-Čechy
    Měděnec (Chomutov)
    Pernštějn (Chomutov)
Keyword
    Assemblage
    Bohemian
    Destabilization
    Formation
    Garnet-phengite-paragonite
    High
    Hory
    Krušné
    Massif
    Metamorphism
    Mountains
    Pelitic
    Pressure
    Rocks
    Significance
    Substitution
    Tschermak
Abstract (in english)
   The metamorphism of low-alumina metapelites along high pressure gradients involves only a few continuous and discontinuous reactions that produce minor variations in modal mineralogy. This is the case with metamorphic rocks forming the (para-)autochthonous sequence in the vicinity of the village of Měděnec (Krušné hory Mts., Bohemian Massif). Metamorphic reactions taking place among micas, garnets and feldspars can be described using Tschermak exchange and NaK -1 exchange. Pressure-temperature conditions for some of theses continuous reactions were calculated from minerals compositions. These calculations suggest that the Tschermak and NaK -1 exchanges are sensitive monitors of pressure and temperature conditions in these rocks, the mineral assemblages of which are unsuitable for experimentally calibrated thermobarometers. The results show metamorphic temperatures of 580-630 C at a pressure of 13-15 kbar during metamorphism of Pre-Variscan basement beneath a nappe sequence
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    5. 2. 2009
Import date
    8. 8. 2012