Publication Date:
2017-04-04
Description:
The coupling/decoupling between the lithosphere and asthenosphere has significant implications for
understanding many important aspects of plate tectonics and geodynamics. To drive plate motion, mantle
convection requires coupling at the lithosphere–asthenosphere (LA) interface. Meanwhile a low viscosity
layer in the asthenosphere is indicative of possible LA decoupling. Here we present an analytical
model of a stratified uppermost mantle structure disturbed by a long-wavelength perturbation (such
as the body tide) to analyse the influence of LA viscosity contrast on the growth (or decay) rates of the
perturbation. We show that the viscosity contrast of 8–10 orders of magnitude would allow a relative
motion of the lithosphere over the asthenosphere due to the long-wavelength perturbations at the rate
of about 10 cm yr 1. These constrains on the viscosity contrast can allow to discriminate between the LA
coupling and decoupling. The growing seismic and mineralogical evidences of a possible ultra low viscosity
asthenospheric layer may be indicative of the LA decoupling and their relative motions due to longwavelength
perturbations, and a contribution of the tidal drag on the plate motion should not be
neglected in the regions of high viscosity contrasts.
Description:
Research
supported by DFG IS203/1-1, Miur-Prin 2008, CNR Eurocores,
TopoEurope, and RASP Program No. 23.
Description:
Published
Description:
1-8
Description:
3.3. Geodinamica e struttura dell'interno della Terra
Description:
JCR Journal
Description:
restricted
Keywords:
Lithosphere dynamics
;
Asthenosphere
;
Viscosity contrast
;
Decoupling
;
Analytical modelling
;
Rayleigh–Taylor instability
;
04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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