Metastability of enstatite in deep subducting lithosphere

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doi: 10.1038/372351a0
Authors:Hogrefe, A.; Rubie, D. C.; Sharp, T. G.; Seifert, F.
Author Affiliations:Primary:
Universität Bayreuth, Bayerisches Geoinstitut, Bayreuth, United States
Volume Title:Nature (London)
Source:Nature (London), 372(6504), p.351-353. Publisher: Macmillan Journals, London, United Kingdom. ISSN: 0028-0836
Publication Date:1994
Note:In English. 36 refs.; illus., incl. 1 table
Summary:Results of multi-anvil high-P experiments are reported in which hot-pressed forsterite + enstatite aggregates were reacted in the stability fields of β-Mg2SiO4 + stishovite,Γ-Mg2SiO4 + stishovite, and MgSiO3 ilmenite, at 16-21 GPa and 1000-1650°C. Whereas forsterite transforms readily to the β-phase at 1200°C and 16 GPa, the transformation of enstatite to the β-phase + stishovite requires much higher T over the same time. At lower T enstatite transforms directly to the ilmenite structure but only at >> 20 GPa. Enstatite should persist metastably to greater depths than olivine in subduction zones transforming directly to the ilmenite structure. The enstatite-ilmenite transformation is accompanied by a large decrease in volume which should increase the stresses in subducting slabs, change the buoyancy forces during subduction and contribute to deep-focus earthquakes. [R.K.H.]
Subjects:Chain silicates; Enstatite; Experimental studies; Geophysics; High pressure; Kinetics; Lithosphere; Mantle; Orthopyroxene; P-T conditions; Phase equilibria; Phase transitions; Pressure; Pyroxene group; Silicates; Slabs; Stability; Subduction zones; TEM data; Transformations; Upper mantle; Volume; Ilmenite structure; Metastability
Abstract Numbers:95M/1645
Record ID:1995005664
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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