Strong textural inheritance between perovskite and post-perovskite in the D" layer

David P Dobson, Nobuyosihi Miyajima, Fabrizio Nestola, Matteo Alvaro, Nicola Casati, Christian Liebske, Ian Wood, Andrew M Walker

Research output: Contribution to journalArticle (Academic Journal)peer-review

34 Citations (Scopus)
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Abstract

The main mineral in the lower mantle, magnesium-silicate perovskite, transforms into a high-pressure, post-perovskite, phase at pressures and temperatures corresponding to the D'' seismic discontinuity approximately 200 km above the core-mantle boundary. The strong elastic anisotropy of post-perovskite has been invoked to explain the observed seismic anisotropy and to infer flow in the D'' region, based on models of textured post-perovskite. Such inferences rely on a knowledge of the mechanisms by which the post-perovskite can obtain texture. It is generally thought that seismic anisotropy in D'' is produced from lattice-preferred orientation generated during plastic deformation; however, it is difficult to explain all of the observed seismic anisotropy in D'' using a single deformation mechanism in post-perovskite. Here we show that strong texture inheritance is possible during transformation from perovskite to post-perovskite using a recently developed fluoride analogue system. If a similar transformation mechanism operates in the Earth, post-perovskite will inherit textures from deformed perovskite and vice versa as lower-mantle material passes into and out of regions of post-perovskite stability. This texture inheritance during the transition from post-perovskite to perovskite, combined with a single slip system in post-perovskite, can explain the seismic anisotropy of the lowermost mantle.
Original languageEnglish
Pages (from-to)575–578
JournalNature Geoscience
Volume6
Early online date16 Jun 2013
DOIs
Publication statusPublished - 2013

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