Thermophysical properties and phase diagrams in the system MgO–SiO 2 –FeO at upper mantle and transition zone conditions derived from a multiple-Einstein method

Michael H.G. Jacobs*, Rainer Schmid-Fetzer, Arie P. van den Berg

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

We applied a lattice vibrational technique, based on representing the vibrational density of states with multiple-Einstein frequencies, to determine consistency of data on thermophysical properties and phase diagrams in the system MgO–FeO–SiO 2 . We present analyses of these data in the temperature range between 0 and 2000 K and pressure range between 0 and 20 GPa. The result is a database containing phases relevant to the Earth upper mantle and transition zone. We show that consistency of different datasets associated with the dissociation of the ringwoodite form of Fe 2 SiO 4 depends on the crucible material that has been used to perform partitioning experiments between ringwoodite and ferropericlase, and that this results in different phase diagrams for FeSiO 3 and the post-spinel part of Mg 2 SiO 4 –Fe 2 SiO 4 . We show that the existence of a phase field coesite + ringwoodite in the phase diagram of FeSiO 3 is possible and that it might be used to fine-tune pressure scales. We demonstrate that the phase boundary between coesite and quartz is very sensitive to the low-temperature heat capacity of coesite and that heat capacity data of β-quartz are too large to be reconciled with the phase boundary between β-quartz and coesite. We compare our results with seismic data associated with the 410 km seismic discontinuity.

Original languageEnglish
Pages (from-to)513-534
Number of pages22
JournalPhysics and Chemistry of Minerals
Volume46
Issue number5
DOIs
Publication statusPublished - 1 May 2019

Funding

M.H.G. Jacobs gratefully acknowledges financial support by the German Research Foundation (DFG) under grant no. JA 1985/1-2. Collaboration between A. van den Berg and M. Jacobs has been supported through The Netherlands Research Center for Integrated Solid Earth Science (ISES) project ME-2.7. Wim van Westrenen is gratefully acknowledged for stimulating discussions. We thank P.I. Dorogokupets and an anonymous reviewer for insightful suggestions and ideas that improved the quality of the manuscript significantly.

FundersFunder number
P.I.
Deutsche ForschungsgemeinschaftJA 1985/1-2
German-Israeli Foundation for Scientific Research and Development
Netherlands Research Centre for Integrated Solid Earth SciencesME-2.7

    Keywords

    • Anharmonicity
    • Elasticity
    • Equation of state
    • Pressure scale
    • Vibrational density of states

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