Fast asthenosphere motion in high-resolution global mantle flow models


A variety of geologic observations point to fast upper mantle flow that may exceed plate tectonic velocities by an order of magnitude. At the same time there is mounting evidence from seismology for flow like structures in the upper 100-200km of the mantle. Here we present a set of geodynamic simulations to link these observations. In a synthetic setting, we include asthenospheric channels of varying thickness, with an extreme case of 100km, and a significant viscosity contrast of up to four orders of magnitude relative to the deeper mantle. Using our new global high resolution code TERRA-NEO, we obtain an increase in velocity by a factor of ten between a 1000km thick and the very thin channel, translating into velocities of ∼20cm/a within the narrow asthenosphere. We further present and verify a simple Poiseuille flow model, predicting that the upper mantle velocity scales with the inverse of the asthenosphere thickness.

  author = {Weism\"uller, Jens and Gmeiner, Bj\"orn and Ghelichkhan, Siavash and Huber, Markus and John, Lorenz and Wohlmuth, Barbara and R\"ude, Ulrich and Bunge, Hans-Peter},
  doi = {10.1002/2015GL063727},
  eid = {2015GL063727},
  journal = {Geophysical Research Letters},
  language = {en},
  number = {18},
  pages = {7429{\textendash}7435},
  title = {Fast asthenosphere motion in high-resolution global mantle flow models},
  volume = {42},
  year = {2015},
%O Journal Article
%A Weismüller, Jens
%A Gmeiner, Björn
%A Ghelichkhan, Siavash
%A Huber, Markus
%A John, Lorenz
%A Wohlmuth, Barbara
%A Rüde, Ulrich
%A Bunge, Hans-Peter
%R 10.1002/2015GL063727
%1 2015GL063727
%J Geophysical Research Letters
%G en
%N 18
%P 7429–7435
%T Fast asthenosphere motion in high-resolution global mantle flow models
%V 42
%D 2015