Phase relations in the system MgO-FeO-SiO2 to 50 GPa and 2000°C: An application of experimental techniques using multianvil apparatus with sintered diamond anvils

• Published in: Journal of Geophysical Research - Solid Earth Vol. 114; no. B2; pp. B02214 - n/a
• Main Authors: Tange, Yoshinori, Takahashi, Eiichi, Nishihara, Yu, Funakoshi, Ken-ichi, Sata, Nagayoshi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01.02.2009; Blackwell Publishing Ltd
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; Experimental mineralogy and petrology; Fe-Mg partitioning; High-pressure behavior; magnesiowüstite; Mantle processes; Mineral Physics; Mineralogy and Petrology; Reactions and phase equilibria; silicate perovskite; Thermodynamics; magnesiowüstite; silicate perovskite; Fe-Mg partitioning; diamonds; perovskite; oxides; lower mantle; stishovite; ferrous iron; X-ray diffraction; concentration; pressure; electrons; phase relations; Pressure effect; depth; temperature; silicates; solubility; framework silicates; transmission electron microscopy; synchrotron radiation; silica minerals
• ISSN: 0148-0227; 2156-2202
• DOI: 10.1029/2008JB005891

Phase relations in the system MgO‐FeO‐SiO2 were investigated between 22 and 47 GPa at 1500°C and 2000°C using multianvil apparatus with sintered diamond anvils. Synthesized samples were analyzed with electron microprobe, analytic transmission electron microscopy, and X‐ray diffraction using synchrotron radiation. Univariant compositions of (Mg,Fe)SiO3 perovskite and (Mg,Fe)O magnesiowüstite coexisting with SiO2 stishovite were determined as functions of pressure and temperature. The maximum iron solubility in perovskite corresponding to the univariant composition gradually increases with increasing pressure and temperature to be more than 30 mol % at 2000°C and pressures above 40 GPa, and a significant pressure effect was found in Fe‐Mg partitioning between perovskite and magnesiowüstite in pressures between 22 and 35 GPa. The iron content of magnesiowüstite dramatically increases from 50 to greater than 90 mol % with increasing pressure, and the Fe‐Mg distribution coefficients between perovskite and magnesiowüstite, KD = (XFePv/XMgPv)/(XFeMw/XMgMw), decrease to less than 0.05. This significant pressure effect in Fe‐Mg partitioning causes strong concentration of ferrous iron in magnesiowüstite with increasing depth in the lower mantle.