Record details

Title
    Radial profiles of temperature and viscosity in the Earth's mantle inferred from the geoid and lateral seismic structure
Statement of responsibility
    Ondřej Čadek, A.P. van den Berg
Author
    Berg, A.P., van den
    Čadek, Ondřej
Language
    anglicky
Source title - serial
    Earth and planetary science letters
Vol./nr.
    Vol. 164, no. 3-4
Pages
    p. 607-615
Year
    1998
Notes
    4 obr., 2 tab., 42 bibl.
    il.
    Zkr. název ser.: Earth planet. Sci. Lett.
Subject group
    geoid
    gradient geotermický
    modelování
    plášť
    seizmologie
    tomografie
    viskozita
    vlastnosti termodynamické
Keyword
    Earth's
    Geoid
    Inferred
    Lateral
    Mantle
    Profiles
    Radial
    Seismic
    Structure
    Temperature
    Viscosity
Abstract (in english)
   In the framework of dynamical modelling of the geoid, we have estimated basic features of the radial profile of temperature in the mantle. The applied parameterization of the geotherm directly characterized thermal boundary layers and values of the thermal gradient in the upper and lower mantle. In the inverse modelling scheme these parameters are related to the observables (geoid and seismic structure of the mantle) through the viscosity profile which is parameterized as an exponential function of pressure and temperature. We have tested10 4 model geotherms. For each of them we have found proper rheological parameters by fitting the geoid with the aid of a genetic algorithm. The geotherms which best fit the geoid show a significant increase of temperature (&600-800°C) close to the 660-km discontinuity. The value of the thermal gradient in the mid-mantle is found to be sub-adiabatic.
   Both a narrow thermal core-mantle boundary layer and a broad region with a superdiabatic regime can produce a satisfactory fit of the geoid. The corresponding viscosity profiles show similarities to previously presented models, in particular in the viscosity maximum occuring in the deep lower mantle. The best-fitting model predicts the values of activation volume V* and energy E* which are in a good agreement with the data from mineral physics, except for V in the lower mantle which is found somewhat lower than the estimate based on melting temperature analysis. An interesting feature of the viscosity profiles is a local decrease of viscosity somewhere between 500 and 1000 km depth which results from the steep increase of temperature in the vicinity of the 660-km discontinuity
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    26. 9. 2007
Import date
    8. 8. 2012