Walker, AM orcid.org/0000-0003-3121-3255, Dobson, DP, Wookey, J et al. (2 more authors) (2018) The anisotropic signal of topotaxy during phase transitions in D′′. Physics of the Earth and Planetary Interiors, 276. pp. 159-171. ISSN 0031-9201
Abstract
While observations and modelling of seismic anisotropy in the lowermost mantle offers the possibility of imaging mantle flow close to the core mantle boundary, current models do not explain all observations. Here, we seek to explain a long-wavelength pattern of shear wave anisotropy observed in anisotropic tomography where vertically polarised shear waves travel faster than horizontally polarised shear waves in the central Pacific and under Africa but this pattern is reversed elsewhere. In particular, we test an explanation derived from experiments on analogues, which suggest that texture may be inherited during phase transitions between bridgmanite (perovskite structured MgSiO3) and post-perovskite, and that such texture inheritance may yield the long-wavelength pattern of anisotropy. We find that models that include this effect correlate better with tomographic models than those that assume deformation due to a single phase in the lowermost mantle, supporting the idea that texture inheritance is an important factor in understanding lowermost mantle anisotropy. It is possible that anisotropy could be used to map the post-perovskite stability field in the lowermost mantle, and thus place constraints on the temperature structure above the core-mantle boundary.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | © 2017 Elsevier B.V. This is an author produced version of a paper published in Physics of the Earth and Planetary Interiors. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | post-perovskite; seismic anisotropy; lowermost mantle; phase transition; mantle convection |
Dates: |
|
Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Funding Information: | Funder Grant number NERC NE/K008803/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 12 May 2017 12:47 |
Last Modified: | 15 May 2018 00:38 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.pepi.2017.05.013 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:116260 |