Podrobnosti záznamu

Název
    White mica 40Ar/39Ar ages of Erzgebirge metamorphic rocks: simulating the chronological results by a model Variscan crustal imbrication
Údaj o odpovědnosti
    Olaf Werner, Hans J. Lippolt
Další názvy
    Orogenic Processes: Quantification and Modelling in the Variscan Belt (Variant.)
Autor
    Lippolt, Hans J.
    Werner, Olaf
Jazyk
    anglicky
Zdrojový dokument - seriál
    Geological society special publication
Svazek/č.
    Vol. 179
Strany
    p. 323-336
Rok
    2000
Poznámky
    10 obr., 1 tab., 2 s.bibl.
    Zkr. název ser.: Geol. Soc. spec. Publ. (London).
Předmětová skupina
    datování Ar/Ar
    fylit
    karbon-spodní
    krušnohorské krystalinikum
    metamorfóza
    modelování
    ochlazování
    slídy
    svor
    tektonika šupinová
    teplota
    vrásnění variské
    výzdvih klenbový
    zóna střižná
Geografické jméno
    ČR-Čechy
    SRN-Sachsen
Klíčové slovo
    40Ar/39Ar
    Ages
    Chronological
    Crustal
    Erzgebirge
    Imbrication
    Metamorphic
    Mica
    Model
    Results
    Rocks
    Simulating
    Variscan
    White
Abstrakt (anglicky)
   In the Erzgebirge, which is part of the Saxo-Thuringian Mis-European Variscides, an 40Ar/39Ar study was performed on white mica and hornblende separates from 68 metamorphic rocks of varying lithologies. Two groups of late Early Carboniferous cooling ages of 340˝2Ma and 329.7˝1.5Ma are distinguished by evaluating spectra shapes. A third group of rocks yielded intermediate aron ages, presumably related either to thermal rejuvenation or to neoformation of white mica during a reheating process 330 Ma ago. A model that explains rejuvenation is proposed. The observed age patterns and the shape of the age spectra cannot be simply explained by assuming a single uplift and exhumation process set in motion by extensive forces. Chronological and structural arguments favour the idea that Variscan crustal imbrication took place during the mineral cooling phase.
   A tectonic process that intercalated, at about 20 km depth, a unit of cool rocks into a much hotter environment suitably models the chronological results. This is shown by a simulation of the age record. Temperature profiles are calculated for both intervalation and subsequent uplift models. Rocks in these profiles, which preserved their 340 Ma signature, are distinguished from those heated 330 Ma ago by contact with adjacent hotter rocks and reset isotopically to varying degrees. The agreement between analytical results and modelled ages favours the crustal imrbication hypothesis as explanation for the age distribution throughout all lithologies
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    18. 6. 2007
Datum importu
    8. 8. 2012