Podrobnosti záznamu

Název
    K-Ar dating of illite fundamental particles separated from illite-smectite
Údaj o odpovědnosti
    N. Clauer, J. Srodon, Juraj Franců, Vladimír Šucha
Autor
    Clauer, N.
    Franců, Juraj, 1957-
    Srodon, J.
    Šucha, Vladimír
Jazyk
    anglicky
Zdrojový dokument - seriál
    Clay minerals
Svazek/č.
    Vol. 32, no. 2
Strany
    p. 181-196
Rok
    1997
Poznámky
    6 obr., 1 fot., 1 tab., 3 s.bibl.
    Zkr. název ser.: Clay Miner.
Předmětová skupina
    datování K/Ar
    diageneze
    illit
    křída-svrchní
    ložisko bentonitu
    minerály jílové
    neogén
    pohřbení
    separační technika
    smektity
    teplota
Geografické jméno
    Maďarsko
    Slovensko
    USA-Montana
Klíčové slovo
    Dating
    Fundamental
    Illite
    Illite-smectite
    K-Ar
    Particles
    Separated
Abstrakt (anglicky)
   Fundamental particles of illite-smectite from bentonites were separated into classes by high-speed centrifugation after infinitive osmotic swelling of mixed-layer crystals, achieved by Na-exchange and dispersion in distilled water. In samples free of detrial contamination, the thinnest fundamental particles yield older K-Ar ages than the kicker fundamental particles. This implies that they do not preferentially lose radiogenic 40Ar due to size, and the illitization process is a crystal growth mechanism (not nucleation plus growth). As a result, any K-Ar age of fundamental illite particles from bentonites is an integral over longer or shorter periods of time, depending on the thermal history of the rocks. In thick bentonite beds, the measured age difference between the beginning of the illitization process at the contact with the host rocks and the end in the centre of the bed records extremely slow K diffusion in these well compacted rocks.
   These data explain why measured K-Ar ages of illite-smectite from bentonites are younger that the corresponding age of shale illitization, inferred from the burial history of the basin. The finest technically separable size-fractions of associated shales (<0.02 m) yield K-Ar dates* greater than the stratigraphic age. This observation points to incomplete recrystallization of detrial illite during burial diagenesis
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    21. 3. 2008
Datum importu
    8. 8. 2012