Podrobnosti záznamu

Název
    A Cautionary Tale of Spinel Peridotite Thermobarometry: an Example from Xenoliths of Kozákov Volcano, Czech Republic
Údaj o odpovědnosti
    Gordon L. Medaris, Herbert F. Wang, John H. Fournelle, John H. Zimmer, Emil Jelínek
Další názvy
    Magmatism and Rift Basin Evolution (Variant.)
Autor
    Fournelle, John H.
    Jelínek, Emil, 1943-
    Medaris, Gordon L., jr.
    Wang, Herbert F.
    Zimmer, John H.
Jazyk
    anglicky
Zdrojový dokument - seriál
    Geolines
Svazek/č.
    Vol. 9
Strany
    p. 92-96
Rok
    1999
Poznámky
    11 diagr., 12 bibl.
Předmětová skupina
    bazanit
    kenozoické vulkanity Českého masivu
    minerály horninotvorné
    neogén
    paleobarometrie
    paleotermometrie
    peridotit
    podmínky P-T
    původ plášťový
    vulkanismus
    xenolit
Geografické jméno
    ČR-Čechy
    Kozákov (Semily)
Klíčové slovo
    Cautionary
    Czech
    Example
    Kozákov
    Peridotite
    Republic
    Spinel
    Tale
    Thermobarometry
    Volcano
    Xenoliths
Abstrakt (anglicky)
   Protogranular and equigranular spinel lherzoliths are abundant in basanite lavas at the Neogene Kozákov volcano, located in the northern Czech republic near the Lužice Fault, which marks the eastern end of the Ohře Rift. Two-pyroxene thermometry yielded 853°-1,045°C for protogranular, 680°-1,065°C for equigranular and 700°-735°C for two composite samples (at P=15kbar). Careful analysis of Ca in olivine and application of the Ca-in-olivine barometer demonstrate that this barometer is unreliable and that geotherms constructed by such application are spurious. The Kozákov basanites erupted at 5 Ma, but were preceded by major regional volcanism at 30 to 35 Ma, and the thermal evolution of the lithosphere has been calculated from an underplating model, based on geological and geophysical data.
   The thermal scenario implies that mantle at shallow depths was heated to higher temperatures and cooled faster than was mantle at deeper levels, and differences in the characteristics of pyroxene exsolution lamellae in shallower xenoliths compared to those in deeper xenoliths are consistent with such an implication. Forcing the xenolith two-pyroxene temperatures onto the Model geotherm at 5 Ma, the time of eruption, indicates that the xenoliths were derived from depths of 32 to 70 km, which is consistent with phase petrology and the depth of the crust-mantle boundary, and that the sub-Kozákov lithosphere has a layered structure, in which protogranular lherzolite at depths of 45 to 68 km is sandwiched between shallower and deeper layers of equigranular lherzolite
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    21. 3. 2008
Datum importu
    8. 8. 2012