Record details

    The Variscan lower continental crust: evidence for crustal delamination from geochemical and petrological investigations
Statement of responsibility
    A. Wittenberg, C. Vellmer, H. Kern, K. Mengel
Other titles
    Orogenic Processes : Quantification and Modelling in the Variscan Belt (Variant.)
    Kern, H.
    Mengel, K.
    Vellmer, C.
    Wittenberg, A.
Source title - serial
    Geological society special publication
    Vol. 179
    p. 401-414
    4 obr., 4 tab., 3 s.bibl.
    Zkr. název ser.: Geol. Soc. spec. Publ. (London).
Subject group
    chemismus hornin
    diskontinuita Mohorovičičova
    hmotová bilance
    kůra kontinentální
    kůra spodní
    kutnohorské krystalinikum
    profil seizmický
    rychlost elastických vln
    vlastnosti fyzikální
    vrásnění variské
Geographical name
    Itálie severní
    Kutná Hora
Abstract (in english)
   Seismic observations along the European Geotraverse (EGT) Central Segment indicate an overall felsic composition of the Variscan crust, including 15 vol.% of mafic lower-crustal (MLC) rocks. As the Variscan continental crust is largely post-Archaean, its bulk composition should be basaltic andesitic rather felsic (tonalitic), because primitive port-Archaean crust was formed by mantle extracted basaltic andesite magmas. The observed proportions of the Variscan continental crustal laxers do not match the requirement of a mafic overall crust. Combining laboratory-derived, in situ seismic data (Vp) with the refraction seismic data and the evidence from geological and geochemical investigations suggests that large amounts of MLC rocks are missing in the present-day lower crust.
   A mass balance calculation of the basaltic andesite bulk crust, considering a refined compilation of the Variscan MLC, gives a volume proportion of 37 vol.% for the felsic and 63 vol.% for the mafic components, for primitive crust prior to collision tecotnics and orogenic root delamination. If large parts of this MLC have undergone eclogite-facies metamorphism at the orogenic root, largge amounts of former basaltic-gabbroic and MLC cumulated could have been subtracted from the crust by its subsequent delamination processes which results in the currently observed proportion of the continental crust of the Variscan Orogen with a redominance of felsic rocks
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
Entered date
    3. 5. 2007
Import date
    8. 8. 2012