Radial Anisotropy in the top 1200 km of the Mantle

MODEL DOWNLOAD

Coming eventually…

Citation:

lnk Beghein, C., and Trampert, J., Probability density functions for radial anisotropy: implications for the upper 1200 km of the mantle, Earth Planet. Sci. Lett., 217 (1-2), 151-162, doi:10.1016/S0012-821X(03)00575-2,  2004

The maps shown below were not included in the paper and are thus complementary to the published figures

Mean 3-D radial anisotropy model
Mean 3-D radial anisotropy model

Before interpreting this model one should remember that this is the mean model, not necessarily the best fitting model, and that it is accompanied by large uncertainties (see below).

This mean model was obtained using the NA and without any prior relationship between the different elastic parameters. It shows a significant anisotropy down to the transition zone, especially below ocean ridges, where we have VSH<VSV and VPH>VPV. We also see a correlation between ξ and Φ circum Pacific in the transition zone, and to a lesser extent between Φ and η.

Standard deviation for radial anisotropy parameters
Standard deviation for radial anisotropy parameters

The mean model obtained using the NA and without any prior relationship between the different elastic parameters shows a correlation between dlnVS and dlnVP, as expected from body wave data, and this justifies scaling P- and S-wave anomalies at these depths in future inversions. Density anomalies appear anti-correlated to velocity perturbations, which may suggest a non-negligible chemical component to the origin of the heterogeneities. Large uncertainties are however associated with density (see below). We also notice that velocity anomalies of 1-2% are present in the transition zone. VS is resolved within uncertainties.

Mean 3-D isotropic model
Mean 3-D degree 8 isotropic model
Standard deviation for isotropic anomalies
Standard deviation for isotropic anomalies

This work was presented at the following meetings and conferences:

  1. Beghein, C., and Trampert, J., Lateral variations in radial anisotropy and consequences for the upper 1200km of the mantle, EGU, Nice, France, Abstract, 2004
  2. Beghein, C., and Trampert, J., Lateral variations in radial anisotropy down to 1200km depth, EOS Transactions, Eos Trans. AGU, 84(46), Fall Meet. Suppl., Abstract, 2003
  3. Beghein, C., and Trampert, J., Lateral variations in radial anisotropy in the upper 1200km of the mantle, The Deep Earth: Theory, Experiment and Observation, Acquafredda di Maratea, Italy, Sept. 2003