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Transformation textures in post‐perovskite: Understanding mantle flow in the D″ layer of the Earth
Author(s) -
Walte N. P.,
Heidelbach F.,
Miyajima N.,
Frost D. J.,
Rubie D. C.,
Dobson D. P.
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl036840
Subject(s) - geology , post perovskite , mantle (geology) , seismic anisotropy , downwelling , anisotropy , silicate perovskite , geophysics , deformation (meteorology) , materials science , mineralogy , optics , physics , upwelling , oceanography
Deformation and texture formation in (Mg, Fe)SiO 3 post perovskite (ppv) is a potential explanation for the strong seismic anisotropy that is found in the D″ layer of the Earth. However, different experimental approaches have resulted in different lattice preferred orientations (LPO) in deformed ppv that have led to ambiguity in the interpretation of deformation in the lowermost mantle. Here, we show that deformation of the analogue substance CaIrO 3 during a phase transformation from perovskite to ppv leads to a transformation texture that differs from the CaIrO 3 ppv deformation texture but resembles the results from ppv deformation experiments in diamond anvil cells. Assuming material spreading parallel to the core‐mantle boundary, our results predict a widespread shear wave splitting with fast horizontal S‐waves, which is compatible with seismic studies. Downwelling material that undergoes a phase transformation may develop a transformation texture that would locally result in vertically polarized fast S‐waves.