Dobson, DP;
(2018)
The anisotropic signal of topotaxy during phase transitions in D″.
Physics of the Earth and Planetary Interiors
, 276
pp. 159-171.
10.1016/j.pepi.2017.05.013.
Preview |
Text
topo_tomo_accepted.pdf - Accepted Version Download (5MB) | Preview |
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.
Type: | Article |
---|---|
Title: | The anisotropic signal of topotaxy during phase transitions in D″ |
Open access status: | An open access version is available from UCL Discovery |
DOI: | 10.1016/j.pepi.2017.05.013 |
Publisher version: | https://doi.org/10.1016/j.pepi.2017.05.013 |
Language: | English |
Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
Keywords: | Post-perovskite, Seismic anisotropy, Lowermost mantle, Phase transition, Mantle convection |
UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
URI: | https://discovery.ucl.ac.uk/id/eprint/1555695 |
Archive Staff Only
View Item |