Podrobnosti záznamu

Název
    What drives remelting of thickened continental crust in the Bohemian Massif?
Autor
    Janoušek, Vojtěch
    Lexa, Ondrej
    Maierová, Petra
    Schulmann, Karel
Jazyk
    anglicky
Typ dokumentu
    článek ve sborníku
Zdrojový dokument - monografie
    Géologie de la France
Strany
    2
Poznámky
    Akce: 2012 ; Sassari
Výraz tezauru
    Moldanubian Unit, Variscan Orogen, partial melting, heat
Klíčové slovo
    Bohemian
    Continental
    Crust
    Drives
    Massif
    Remelting
    Thickened
Abstrakt (anglicky)
   Following the crustal collision and the thermal peak of the regional metamorphism, the Moldanubian Zone was penetrated by voluminous anatectic plutons of the Moldanubian Plutonic Complex (MPC). The precise U-Pb Zrn and Mnz geochronology indicates that over its 80 % was constructed during the narrow time period of ~331-323 Ma (Gerdes et al., 2003), forming coarse-grained, Kfs-phyric Weinsberg granitoids (331-323 Ma) and porphyritic two-mica Eisgarn granites (328-326 Ma). Finally, small volumes of fine-grained I-type granites-granodiorites intruded at 319-300 Ma. Thus there seems to be a significant time gap between the mid-crustal emplacement of the hot granulite bodies with ultrapotassic plutons on the one hand, and widespread partial melting of the Moldanubian middle crust, in particular the Monotonous Group paragneisses, on the other. As the amount of basic magmas spatially associated with the Weinsberg and Eisgarn granitic suites is severely limited, ruled out is not only advection
   of heat by mantle-derived magmas, but also the mantle processes such as slab break off and lithospheric delamination (Henk et al., 2000). The preferred scenario remains internal heating by radioactive decay (Gerdes et al., 2000) associated with horizontal conductive heat transfer resulting from equilibration of perturbed thermal field. We suggest that the advection-dominated vertical material transfers driven by gravity redistribution operated along two major diapir-like megastructures and caused burial of colder and fertile metapelitic rocks in marginal synforms (Warren and Ellis, 1996). These metasediments may have become partially molten during the thermal relaxation, producing typical crustally-derived (S-type) granitoids. In this contribution, we test various length and time scales of gravity overturn processes and the influence of heat redistribution within thickened root along with mantle-hosted thermal anomaly.
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (RIV)
Zdrojový formát
    R
Datum importu
    15. 10. 2014