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Titolo:
Stabilities and equations of state of dense hydrous magnesium silicates
Autore:
Angel, RJ; Frost, DJ; Ross, NL; Hemley, R;
Indirizzi:
Univ Bayreuth, Bayer Geoinst, D-95440 Bayreuth, Germany Univ Bayreuth Bayreuth Germany D-95440 eoinst, D-95440 Bayreuth, Germany Univ Coll London, Dept Geol Sci, London WC1E 6BT, England Univ Coll London London England WC1E 6BT l Sci, London WC1E 6BT, England Carnegie Inst Washington, Geophys Lab, Washington, DC 20015 USA Carnegie Inst Washington Washington DC USA 20015 Washington, DC 20015 USA
Titolo Testata:
PHYSICS OF THE EARTH AND PLANETARY INTERIORS
fascicolo: 1-4, volume: 127, anno: 2001,
pagine: 181 - 196
SICI:
0031-9201(200112)127:1-4<181:SAEOSO>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
X-RAY-DIFFRACTION; NOMINALLY ANHYDROUS MINERALS; HIGH-TEMPERATURE ELASTICITY; SINGLE-CRYSTAL FORSTERITE; MANTLE TRANSITION ZONE; RIGID UNIT MODES; HIGH-PRESSURE; THERMODYNAMIC PROPERTIES; SUBDUCTION ZONES; PHASE-RELATIONS;
Keywords:
hydrous phases; equations of state; thermodynamic properties phase equilibria; subduction;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
106
Recensione:
Indirizzi per estratti:
Indirizzo: Angel, RJ Univ Bayreuth, Bayer Geoinst, POB 101251, D-95440 Bayreuth, Germany Univ Bayreuth POB 101251 Bayreuth Germany D-95440 euth, Germany
Citazione:
R.J. Angel et al., "Stabilities and equations of state of dense hydrous magnesium silicates", PHYS E PLAN, 127(1-4), 2001, pp. 181-196

Abstract

The thermodynamic stability of high-pressure phases in the ternary System MgO-SiO2-H2O is reviewed with special emphasis on hydrated phases includingthe "alphabet phases". On the basis of recent experimental data, a stability diagram for these phases along a geotherm appropriate for a subducting slab is constructed. This suggests that at realistic water contents, the breakdown of antigorite will produce olivine plus phase A in the upper mantle,but that the ability of wadsleyite to accommodate wt.% levels of water means that phases E and D are unlikely to occur in the upper portion of the transition zone. For the lower part of the transition zone in which ringwoodite becomes stable, the coexisting hydrous phase would be superhydrous phaseB, provided ringwoodite is not able to accommodate significant amounts of water. At the top of the lower mantle, phase D is stable but only at temperatures below 1300 degreesC. As the maximum solubility of H2O in magnesium silicate perovskite is also quite low stabs may dehydrate somewhat as they enter the lower mantle. The available thermodynamic data for these phases is also reviewed. From the most recent measurements of equations of state, it is concluded that theelasticity of the phases in the MgO-SiO2-H2O ternary system is primarily dependent upon the density and not upon the water content. It is, therefore,concluded that the presence of even significant amounts of hydrated phasesin subducting slabs could not be unequivocally identified from seismological observations, (C) 2001 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 12/07/20 alle ore 09:20:39