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Global mantle circulation models with thermodynamically self consistent mineralogy: bridging the geodynamic/seismic gap

Bunge, H., G. Steinle-Neumann, A. Piazzoni, B. Schuberth, C. Moder, and J. Oeser (2007), Global mantle circulation models with thermodynamically self consistent mineralogy: bridging the geodynamic/seismic gap, in American Geophysical Union, Fall Meeting 2007, abstract #U34A-04, pp. A4+.

Abstract
Seismic tomography is a powerful tool to aide plate reconstructions. Still its use has been hampered mainly because we don't understand very well how to interpret seismic images in terms of temperature and composition. Notable examples are observations of anti-correlation of bulk sound and shear velocity near the bottom of the mantle and a general lack of strong compressional heterogeneity in the lower mantle, both of which have given rise to a variety of speculations on lower mantle dynamics and its relation to past plate motion. Here we address this fundamental problem directly by employing a newly published, thermodynamically self consistent mantle mineralogy model, derived from considerations of Gibbs free energy minimisation of the mantle phase assemblage, which provides us with estimates of density and elastic constants for a wide range of lower mantle P,T conditions. We combine the model with simulations of global mantle circulation, where the very high numerical grid point resolution of less than 20 km throughout the mantle, amounting to more than 100 million grid points totally, is sufficient to achieve a vigorous regime of high Rayleigh number thermal convection that lies within the parameter range for which the mineralogic model was validated. We find a number of important results. For example, the hot spot flux is likely to exceed 10 TW, giving hot spots a more prominent role than is commonly believed. We also find that the anti-correlation of bulk sound and shear, and the low level of compressional wave speed arise naturally in our mineralogy/geodynamics simulations under the assumption of an isochemical mantle, greatly facilitating the interpretation of seismic heterogeneity in terms of past subduction. We will discuss these findings and explore their consequences for the development of next generation geodynamic earth models.
Further information
BibTeX
@inproceedings{id1682,
  author = {H. Bunge and G. Steinle-Neumann and A. Piazzoni and B. Schuberth and C. Moder and J. Oeser},
  booktitle = {American Geophysical Union, Fall Meeting 2007, abstract #U34A-04},
  month = {dec},
  pages = {A4+},
  title = {{Global mantle circulation models with thermodynamically self consistent mineralogy: bridging the geodynamic/seismic gap}},
  year = {2007},
  language = {en},
  url = {http://adsabs.harvard.edu/abs/2007AGUFM.U34A..04B},
}
EndNote
%A Bunge, H.
%A Steinle-Neumann, G.
%A Piazzoni, A.
%A Schuberth, B.
%A Moder, C.
%A Oeser, J.
%D 2007
%P A4+
%T Global mantle circulation models with thermodynamically self consistent mineralogy: bridging the geodynamic/seismic gap
%U http://adsabs.harvard.edu/abs/2007AGUFM.U34A..04B
%8 dec
%B American Geophysical Union, Fall Meeting 2007, abstract #U34A-04
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Printed 20. Aug 2019 18:17