Seismological properties of D″ and the structure of a thermal boundary layer

Doornbos D.J., Spiliopoulos S. and Stacey F.D. (1986) Seismological properties of D″ and the structure of a thermal boundary layer. Physics of the Earth and Planetary Interiors, 41 4: 225-239. doi:10.1016/0031-9201(86)90002-6


Author Doornbos D.J.
Spiliopoulos S.
Stacey F.D.
Title Seismological properties of D″ and the structure of a thermal boundary layer
Journal name Physics of the Earth and Planetary Interiors   Check publisher's open access policy
ISSN 0031-9201
Publication date 1986-01-31
Sub-type Article (original research)
DOI 10.1016/0031-9201(86)90002-6
Volume 41
Issue 4
Start page 225
End page 239
Total pages 15
Subject 3103 Astronomy and Astrophysics
1908 Geophysics
3101 Physics and Astronomy (miscellaneous)
1912 Space and Planetary Science
Abstract Temperature calculations based on published seismic velocity models, assuming chemical and phase homogeneity of D″, have produced results that are not in satisfactory agreement with predictions based on boundary layer theory. It is shown here that this discrepancy can be eliminated by reinterpreting the seismic information on D″ in either of the following ways: (1) up to a factor two reduction in the estimated D″ temperature increment results from a relatively small change in the relation between the P and S velocity gradients, which may be permissible in view of the spread in the present observational data; and (2) if D″ is seismically anisotropic then five elastic constants are needed to fully describe the simplest form of anisotropy (uniaxial), and four of these constants are needed to determine the temperature profile. On the basis of seismic diffraction modelling with anisotropic D″ it is concluded that only two elastic constants are effectively constrained by the present data set of P and SH. It is found that the required temperature correction due to a small amount of anisotropy (a few percent in S velocity at the core-mantle boundary and reducing to zero at the top of D″) can be up to about 400 K. Another complicating factor is that both the spread in the data and seismic effects equivalent to anisotropy may be caused in part by heterogeneity of D″. Moreover, if the heterogeneity is in the form of patches of material intrinsically denser than the bulk of the mantle, then the constraints imposed by thermal boundary layer theories apply only to the areas of normal lower mantle material.
Q-Index Code C1
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
 
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