Velocity crossover between hydrous and anhydrous forsterite at high pressures
نویسندگان
چکیده
منابع مشابه
Melting of Forsterite, Mg<sub>2</sub>SiO<sub>4</sub>, From 9.7 to 16.5 GPa
A multianvil apparatus ha been used to determine th pressure-temperature mel ing curve of forsterite from 9.7 to 16.5 GPa. At 10.1 GPa a singular point occurs that marks the change from congruent melting at lower pressures to incongruent melting (forsterite periclase + liquid) at higher pressures. The melting curve also passes through two invariant points. At one (15.6 GPa, 2310øC), the phases ...
متن کاملCompressibility of water in magma and the prediction of density crossovers in mantle differentiation.
Hydrous silicate melts appear to have greater compressibility relative to anhydrous melts of the same composition at low pressures (<2GPa); however, at higher pressures, this difference is greatly reduced and becomes very small at pressures above 5GPa. This implies that the pressure effect on the partial molar volume of water in silicate melt ( partial differentialV-H2O/ partial differentialP) ...
متن کاملForsterite, hydrous and anhydrous wadsleyite and ringwoodite (Mg2SiO4): 29Si NMR results for chemical shift anisotropy, spin-lattice relaxation, and mechanism of hydration
We present a detailed 29Si NMR spectroscopic study of isotopically enriched samples of forsterite and of anhydrous and hydrous wadsleyite and ringwoodite (α, β, and γ phases of Mg2SiO4), which complement previous extensive studies of these minerals by XRD and vibrational spectroscopy. VISi is not detected in any of the phases at levels of about 0.1 to 0.5%. When coupled with recent theoretical ...
متن کاملCrystal chemistry of hydrous forsterite and its vibrational properties up to 41 GPa
The crystal structure of hydrous pure magnesium forsterite (Mg2SiO4) containing 8900 ppmw H2O, synthesized at 12 GPa and 1250 °C, has been refined. The major hydration mechanism appears to be M1 cation vacancy with protonation of the O1-O2 octahedral edge of M1. Raman spectra up to 41 GPa show strong coupling between the two Ag modes (824.4 and 856.2 cm–1). Mode Grüneisen parameters γi related ...
متن کاملEffect of water on the sound velocities of ringwoodite in the transition zone
High-pressure elasticity studies will play a central role in efforts to constrain the potential hydration state of the Earth's mantle from seismic observations. Here we report the effects of 1 wt% H2O (as structurally bound OH) on the sound velocities and elastic moduli of singlecrystal ringwoodite of Fo90 composition, thought to be the dominant phase in the deeper part of the transition zone b...
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تاریخ انتشار 2010