Record details

Title
    Metapegmatites in the western Bohemian massif : Ages of crystallisation and metamorphic overprint, as constrained by U-Pb zircon, monazite, garnet, columbite and Sr-Rb muscovite data
Statement of responsibility
    Johannes Glodny, B. Grauert, Jiří Fiala, Zdeněk Vejnar, A. Krohe
Author
    Fiala, Jiří
    Glodny, Johannes
    Grauert, B.
    Krohe, A.
    Vejnar, Zdeněk
Language
    anglicky
Source title - serial
    Geologische Rundschau
Vol./nr.
    Vol. 87, no. 1
Pages
    p. 124-134
Year
    1998
Notes
    2 obr., 2 tab., 2 s.bibl.
    Zkr. název ser.: Geol. Rdsch.
Subject group
    bohemikum
    datování Rb/Sr
    datování U/Pb
    domažlické krystalinikum
    intruze
    metamorfika
    metamorfóza
    ordovik
    pegmatit
    tepelské krystalinikum
Geographical name
    ČR-Čechy
    Domažlice
    Kříženec (Tachov)
    Meclov (Domažlice)
    Mračnice (Domažlice)
    Nezdice (Karlovy Vary)
    Ohnišťovice (Domažlice)
    Otov (Domažlice)
    SRN-Bayern
    Stráž (Domažlice)
    Zhořec (Tachov)
    Ždánov (Domažlice)
Keyword
    Ages
    Bohemian
    Columbite
    Constrained
    Crystallisation
    Data
    Garnet
    Massif
    Metamorphic
    Metapegmatites
    Monazite
    Muscovite
    Overprint
    Sr-Rb
    U-Pb
    Western
    Zircon
Abstract (in english)
   ranitic metapegmatites of two crystallune units of the western Bohemia massif, the Zone of Erbendorf-Vohenstrauss in Germany (ZEV), and the Zone of Teplá-Domažlice in the Czech Republic (ZTD) have been dated by means of U-Pb and Rb-Sr methods. Ages interpreted to reflect emplacement and crystallisation of the pegmatites were found consistently to be approximately 480 Ma, as constraned by U-Pb analyses of primary magmatic zircon, monazite, garnet and columbite, and by Rb-Sr analyses of large pegmatitic muscovites. Later Devonian amphibolite-facies metamorphism caused ductile shearing of the pegmatites, leading to partial recrystallisation of pegmatitic material. A metamorphic, fine-grained generation of muscovite yielded consistent Rb-Sr ages of 371-376 Ma for both the ZEV and the ZTD, interpreted as dating the end of deformational activity. The Rb-Sr system of the large pegmatitic muscovites turned out to remain closed up to metamorphic temperatures of 600°C.
   Deformation at elevated temperatures is identified as the dominant mechanism for opening of the Rb-Sr system of primary muscovites: apparent ages grade towards Devonian ages as the muscovites become more deformed and fragmented. The data derived from the metapegmatites point to a similar or common tectonometamorphic evolution for the ZEV and the ZTD since the Ordovician. Furthermore, the magmatic formation of granites implies an upper crustal position of the intruded rocks in Lower Ordovician times, clearly documenting the existence of two distinct metamorphic cycles. In contrast to this, in the Neighbouring part of the Moldanubian, only unmetamorphosed granitic pegmatites with intrusion ages around 320 Ma are observed
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    3. 1. 2008
Import date
    8. 8. 2012