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| Titel |
Seismic tomography and mixing in the deep earth |
| VerfasserIn |
W. R. Peltier, G. Pari, A. M. Dziewonski |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 2, no. 3/4 ; Nr. 2, no. 3/4, S.194-205 |
| Datensatznummer |
250000254
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| Publikation (Nr.) |
 copernicus.org/npg-2-194-1995.pdf |
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| Zusammenfassung |
| Recently constructed tomographic models of the lateral
heterogeneity of elastic properties in the Earth's mantle are contrasted in terms of their
implications concerning the extent to which the endothermic phase transformation at 660 km
depth is influencing the radial style of mixing. Previously published whole mantle and
split mantle tomographic reconstructions, SH8/WMI3 and SH8/U4L8 respectively, fit the
seismic observations equally well but disagree on the extent to which radial mixing may be
impeded across this depth horizon. We show that inferences from seismic tomographic images
based on the application of diagnostic functions (global and regional variance spectra and
the radial correlation function) lead to the conclusion that the mantle circulation is
whole mantle in style if model SH8/WM13 is employed. The split mantle tomographic
inversion SHS/U4L8 leads to the contradictory conclusion that the mantle circulation is
significantly impeded across the 660 km depth horizon. This latter interpretation is
reinforced when we employ the new higher resolution split mantle model SH12/U7L5 in our
calculations. We demonstrate that the depth-dependent radial heat flow delivered by both
of the split models implies the existence of a thermal boundary layer at 660 km depth, and
therefore significant layering, whereas that delivered by the whole mantle model does not.
By insisting that the depth-dependent viscosity profile of the mantle be compatible with
the thermal structure if the flow were layered, we argue that the split mantle tomographic
inversions lead to a self-consistent description of geodynamic constraints (geoid and
postglacial rebound data). |
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