Record details

Title
    SHRIMP U-Pb zircon geochronology of the Strzelin gneiss, SW Poland: evidence for a Neoproterozoic thermal event in the Fore-Sudetic Block, Central European Variscides
Statement of responsibility
    Teresa Oberc-Dziedzic, Krystyna Klimas, Ryszard Kryza, C. Mark Fanning
Author
    Fanning, C. Mark
    Klimas, Krystyna
    Kryza, Ryszard
    Oberc-Dziedzic, Teresa
Language
    anglicky
Source title - serial
    International journal of Earth sciences (Geologische Rundschau)
Vol./nr.
    Vol. 92, no. 5
Pages
    p. 701-711
Year
    2003
Notes
    7 obr., 1 tab., 3 s. bibl.
    il.
    Zkr. název ser.: Int. J. Earth Sci. (Geol. Rdsch.)
Subject group
    brunovistulikum
    datování U/Pb
    metamorfóza
    paleozoikum-spodní
    proterozoikum
    protolit
    přesmyk
    původ korový
    rula
    silesikum
    vrásnění kadomské
    vrásnění variské
    západosudetská oblast
    zirkon
    zonálnost krystalu
Geographical name
    ČR-Morava
    Polsko - jihozápad
Keyword
    Block
    Central
    European
    Evidence
    Fore-Sudetic
    Geochronology
    Gneiss
    Neoproterozoic
    Poland
    SHRIMP
    Strzelin
    SW
    Thermal
    U-Pb
    Variscides
    Zircon
Abstract (in english)
   Zircon ages recorded in gneissic rocks have recently been used as criteria to define and correlate various tectonic units and crustal blocks in the central European Variscides. A SHRIMP U-Pb zircon geochronological study of the Strzelin gneiss in the Fore-Sudetic Block (SW Poland) indicates the presence of: (1) inherited zircon cores of Palaeo- to Mesoproterozoic 206Pb-238U ages (between ca. 2,000 and 1,240 Ma), and (2) zoned rims of Neoproterozoic age with two distinct means of 600+-7 and 568+-7 Ma. The Proterozoic age range of the cores suggests that different Precambrian crustal elements were the source for the protolith of the gneiss. A likely scenario is the erosion of various Proterozoic granites and gneisses, sedimentation (after 1,240 Ma), and partial resistance of the original components to subsequent metamorphic dissolution and/or anatectic resorption (in Neoproterozoic times).
   The zoned zircon rims of both of the younger Neoproterozoic ages are indistinguishable in the cathodoluminescence images. The data are interpreted in terms of two different thermal events inducing zoned zircon overgrowth at ca. 600 and 568 Ma. In general, the new results confirm earlier assumptions of the Proterozoic age of the gneiss protoliths, and indicate their similarity to orthogneisses in the East Sudetes tectonic domain (e.g. the Velké Vrbno and Desná gneisses). The Neoproterozoic dates are different from the age of 504+-3 reported earlier for the Gosciecice gneiss from a neighbouring locality in the Strzelin Massif. The new data strongly indicate a Moravo-Silesian (Bruno-Vistulian) affinity for the Strzelin gneiss and support the hypothesis that the Strzelin Massif lies within the tectonic boundary zone between the West- and East Sudetes domains, which represents the northern continuation of the Moldanubian Thrust
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    7. 4. 2008
Import date
    8. 8. 2012