Podrobnosti záznamu

Název
    Bullen's parameter "éta": a link between seismology and geodynamical modelling
Údaj o odpovědnosti
    Ctirad Matyska, David A. Yuen
Autor
    Matyska, Ctirad
    Yuen, David A.
Jazyk
    anglicky
Zdrojový dokument - seriál
    Earth and planetary science letters
Svazek/č.
    Vol. 198, no. 3-4
Strany
    p. 471-483
Rok
    2002
Poznámky
    7 obr., 45 bibl.
    il.
    Zkr. název ser.: Earth planet. Sci. Lett.
Předmětová skupina
    model matematický
    plášť
    proces adiabatický
    proudění konvekční
    seizmologie
    termodynamika
Klíčové slovo
    Bullen's
    éta
    Geodynamical
    Link
    Modelling
    Parameter
    Seismology
Abstrakt (anglicky)
   Valuable information concerning the style of mantle density stratification can be gleaned from the spatial distribution of Bullen's parameter. By means of numerical modelling of 2-D cartesian convection and by monitoring this with the 2-D field of the local Bullen's parameter values, which were obtained by post-processing the convection results, we show that the local adiabaticity is seriously influenced by the presence of an endothermic phase transition at 670 km depth. In this situation the upper mantle suffers much more from non-adiabatic effects than the lower mantle. We have also empleyed the 3-D distributions of density and seismic velocities from the model of Ishii andTromp based on free oscillation observations and constructed 3-D local Bullen's parameter for a spherical Earth.
   In the lower mantle we find that there is a striking similarity in the range of magnitudes of the local Bullen's parameter calculated from convection and those inferred from the splitting of seismic free oscillations. The morphologies of subadiabatic regions in the deep mantle under Africa and the central Pacific would suggest a thermal-chemical nature of the superplumes. Their vertical extent is limited to around 400 km above the core-mantle boundary (CMB). Underneath the Icelandic area in the North Atlantic such an subadiabatic region in the deep mantle above the CMB cannot be discerned. We conclude that the mantle is not as adibatic as has commonly been held
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    26. 9. 2007
Datum importu
    8. 8. 2012