Premium
Molten (Mg 0.88 Fe 0.12 ) 2 SiO 4 at lower mantle conditions: Melting products and structure of quenched glasses
Author(s) -
Williams Quentin
Publication year - 1990
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl017i005p00635
Subject(s) - liquidus , pyroxene , silicate , stoichiometry , olivine , materials science , mineralogy , wüstite , analytical chemistry (journal) , geology , chemistry , metallurgy , oxide , organic chemistry , alloy , chromatography
Infrared spectra of quenched magnesium silicate glasses synthesized by fusing olivine at pressures in excess of 50 GPa and temperatures greater than 2500 K demonstrate that silicon is dominantly present in four‐fold coordination with respect to oxygen within these quenched glasses. This low coordination is attributed, by analogy with the structural behavior of glasses compressed at 300 K, to the instability of higher coordinations in glasses of these compositions on decompression. Spectra of glasses formed in a hydrous environment document that water is extensively soluble in melts at these high pressures and temperatures. Also, these results are consistent with the melting of (Mg 0.88 Fe 0.12 ) 2 SiO 4 compositions to liquids near pyroxene in stoichiometry under these conditions, with iron‐rich magnesiowüstite being the liquidus phase.