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Strong inheritance of texture between perovskite and post-perovskite in the D'' layer

DOI: 10.1038/ngeo1844 DOI Help

Authors: David P. Dobson (University College London; ETH Zürich) , Nobuyosihi Miyajima (Universität Bayreuth) , Fabrizio Nestola (University of Padova) , Matteo Alvaro (University of Padua) , Nicola Casati (Swiss Light Source) , Christian Liebske (ETH Zürich) , Ian G. Wood (University College London) , Andrew M. Walker (Bristol University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Geoscience , VOL 6 (7) , PAGES 575 - 578

State: Published (Approved)
Published: June 2013
Diamond Proposal Number(s): 7616

Abstract: About 200 km above the core-mantle boundary, the D '' seismic discontinuity marks the depth where magnesium silicate perovskite-the main mantle mineral-is transformed into its high-pressure phase of post-perovskite(1,2). Observations of seismic anisotropy within the D '' region are inferred to arise fromtextures within post-perovskite(3-5) that are created by flow in the deep mantle. Specifically, mantle flowis thought to cause post-perovskite to deform, creating a lattice-preferred orientation within the post-perovskite(6-10). However, it is difficult to explain all of the observed patterns of seismic anisotropy in the D '' region from this deformation mechanism alone. Here we use a low-pressure fluoride analogue system(11) to study the transformation from perovskite to post-perovskite in laboratory experiments. We find that post-perovskite can inherit texture from the perovskite phase. If a similar transformation mechanism operates in the Earth, post-perovskite will inherit textures from deformed perovskite and vice versa, as lowermantle material passes into and out of the D '' region. We find that this textural inheritance, combined with lattice-preferred orientation in post-perovskite, can explain the observed patterns of anisotropy in the lowermost mantle.

Journal Keywords: Geodynamics

Subject Areas: Earth Science

Instruments: I15-Extreme Conditions

Added On: 26/09/2013 12:55

Discipline Tags:

Earth Sciences & Environment Mineralogy Geology

Technical Tags:

Diffraction Single Crystal X-ray Diffraction (SXRD)