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Discovery of post-perovskite phase transition and implications for the nature of the D" layer of the mantle

Kei Hirose and Katsuyuki Kawamura
Discovery of post-perovskite phase transition and implications for the nature of the D" layer of the mantle (in Advances in high-pressure mineralogy, Eiji Ohtani (editor))
Special Paper - Geological Society of America (2007) 421: 37-46

Abstract

MgSiO (sub 3) perovskite is a principal mineral in the upper part of the lower mantle, but its stability and possible phase transition at greater depths have long been uncertain. Recently, a new high-pressure MgSiO (sub 3) polymorph called "post-perovskite" was discovered above 125 GPa and 2500 K on the basis of X-ray diffraction measurements in a laser-heated diamond anvil cell (LH-DAC). Crystal structure of post-perovskite was first determined to be orthorhombic (space group: Cmcm) by molecular dynamics (MD) calculations. The first-principles theoretical calculations also confirmed the stability of this new phase. These results suggest that MgSiO (sub 3) -rich post-perovskite is a predominant mineral below 2500-2700 km depth near the base of the mantle. The D" layer has long been the most enigmatic region in Earth's interior. The post-perovskite phase can account for the large seismic anomalies observed in the D" region, such as D" discontinuity, polarization anisotropy, and anticorrelation between S-wave and bulk sound velocities. The long-term enigma may be explained with this newly discovered crystal.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 421
Title: Discovery of post-perovskite phase transition and implications for the nature of the D" layer of the mantle
Title: Advances in high-pressure mineralogy
Author(s): Hirose, KeiKawamura, Katsuyuki
Author(s): Ohtani, Eijieditor
Affiliation: Tokyo Institute of Technology, Department of Earth and Planetary Sciences, Tokyo, Japan
Affiliation: Tohoku University, Institue of Mineralogy, Petrology, and Economic Geology, Sendai, Japan
Pages: 37-46
Published: 2007
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
ISBN: 978-0-8137-2421-8
References: 64
Accession Number: 2008-044744
Categories: Geophysics of minerals and rocks
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200813
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