A Metastable Aluminosilica Compound for Aluminum and Water Transport to the Upper Mantle

It has been suggested that crystalline “phase egg,” AlSiO3OH, with a ratio Al/Si=1 could carry aluminum and water to the mantle but its natural occurrences are still speculative. An amorphous phase with a fixed and unique, deep metastable eutectic Al2Si2O7 composition was produced in laboratory expe...

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Bibliographic Details
Main Authors: Frans J. M. Rietmeijer, Joseph A. Nuth
Format: Article
Language:English
Published: Wiley 2009-01-01
Series:International Journal of Geophysics
Online Access:http://dx.doi.org/10.1155/2009/909431
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Summary:It has been suggested that crystalline “phase egg,” AlSiO3OH, with a ratio Al/Si=1 could carry aluminum and water to the mantle but its natural occurrences are still speculative. An amorphous phase with a fixed and unique, deep metastable eutectic Al2Si2O7 composition was produced in laboratory experiments wherein conditions favored kinetically controlled formation of amorphous solids. This experimentally produced kaolinite-dehydroxylate is highly reactive and it is proposed as the precursor of phase egg in subducting slabs of crustal rocks. If so, metastable phases play a role in subduction zones and it then follows that the processes and resulting conditions in these environments can be nonuniform and discontinuous at least at micrometer scales.
ISSN:1687-885X
1687-8868