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Mechanism of the gamma-beta phase transformation of Mg2SiO4 at high temperature and pressureThe results of experiments on the phase transformation of Mg2SiO4 olivine at 15 GPa pressure in a multianvil cell are reported. At this pressure and a temperature of 900 C, early formed metastable gamma-spinel transforms partially to the beta-phase. The observed microstructures, which are similar to those in shocked meteorites, show that the gamma-to-beta transformation can occur either by diffusion-controlled growth or by a martensitic mechanism, depending on how far the pressure-temperature conditions deviate from their values at phase equilibrium. The results suggest that the diffusion-controlled mechanism is most likely to operate at the beta/gamma phase boundary in the mantle, but martensitic beta-to-gamma transformation might occur in subduction zones and could reduce the shear strength of the subducting slab.
Document ID
19910034042
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Rubie, D. C.
(Bayreuth, Universitaet Federal Republic of Germany, United States)
Brearley, A. J.
(New Mexico, University Albuquerque, United States)
Date Acquired
August 15, 2013
Publication Date
December 13, 1990
Publication Information
Publication: Nature
Volume: 348
ISSN: 0028-0836
Subject Category
Geophysics
Accession Number
91A18665
Distribution Limits
Public
Copyright
Other

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