Record details

Title
    Influence of the load wavelength on the permeability of a viscosity interface in the mantle
Statement of responsibility
    Hana Čížková, Ondřej Čadek, Arie P. Van den Berg
Author
    Čadek, Ondřej
    Čížková, Hana
    Van den Berg, Arie P.
Language
    anglicky
Source title - serial
    Studia geophysica et geodaetica
Vol./nr.
    Roč. 41, č. 1
Pages
    s. 64-72
Year
    1997
Notes
    4 obr., 2 s.bibl.
    il.
    Zkr. název ser.: Stud. geophys. geod. (Praha)
Subject group
    délka vlnová
    diskontinuita
    permeabilita
    plášť
    seizmologie
    viskozita
Geographical name
    Země
Keyword
    Influence
    Interface
    Load
    Mantle
    Permeability
    Viscosity
    Wavelength
Abstract (in english)
   Assuming a radially stratified Newtonian mantle in a steady-state approximation we demonstrate that the permeability of a viscosity interface at 660-km depth strongly depends on the wavelenght of buoyancy forces driving the flow. The flow induced by long-wavelength loads penetrates through the boundary freely even if the viscosity increases by two orders. In contrast, the boundary is practically impermeable for short-wavelength loads located in the upper mantle. Thus, a stepwise increase of viscosity is a significant obstacle for small descending features in the upper mantle, but huge upper mantle downwelling or upwelling formed in the-lower mantle can overcome it easily. This indicates that certain care is necessary in interpreting the seismic structure of the mantle by means of flow models.
   The global tomographic image includes only the first few degrees of the harmonic series and, consequently, its interpretation in terms of a present-day flow field results in a predominantly whole-mantle circulation even for extreme viscosity contrasts
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    28. 3. 2008
Import date
    8. 8. 2012