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

Abstract

[1] Phase relations in the system MgO-FeO-SiO 2 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)SiO 3 perovskite and (Mg,Fe)O magnesiowüstite coexisting with SiO 2 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, K D = (X Fe Pv /X Mg Pv )/(X Fe Mw /X Mg Mw ), 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.

Composition dependence of spin transition in (Mg,Fe)SiO3bridgmanite

“…From 25-50 GPa, solubility of FeSiO 3 in bridgmanite increases from ~20 to ~40% FeSiO 3 (e.g., Tange et al 2009). Above ~50 GPa, the bridgmanite to bridgmanite-plus-oxides phase boundary must change slope to reach the higher solubility of FeSiO 3 reported in recent experiments in the diamond-anvil cell (Tateno et al 2007;Dorfman et al 2013): by ~70 GPa, the solubility of FeSiO 3 increases to at least 75% FeSiO 3 .…”

P‐V‐T equation of state of MgSiO3 perovskite based on the MgO pressure scale: A comprehensive reference for mineralogy of the lower mantle

“…The SDMA experiments were carried out at beamline BL04B1, SPring‐8, using a Kawai‐type multi anvil apparatus, SPEED‐Mk.II [ Katsura et al , 2004], and sintered diamond anvils with truncated edge length of 1.5 mm. High‐pressure cell assemblages were the same as those described by Tange et al [2008], and similar to those used by Tange et al [2009b] and Stagno et al [2011]. LaCrO 3 cylindrical furnaces were used with graphite X‐ray windows, and temperatures were measured using W 97 Re 3 ‐W 75 Re 25 thermocouples.…”

“…The incident X‐ray was focused to 0.006 mm in diameter (FWHM) by using stacked‐compound refractive lenses (CRL). A distance from samples to the IP, wavelength of the monochromatic X‐ray, tilt angles of the IP, and pixel sizes of the IP reader were calibrated from lattice parameters of a CeO 2 standard [e.g., Tange et al , 2009b]. In both measurements, dimensions of incident X‐rays were smaller than the sample sizes, which were also smaller than the heated region in the high‐pressure cell.…”

Deep Earth Structure: Lower Mantle and D″

“…Extensive theoretical and experimental mineral physics research continues to characterize the equations of state, effects of minor components like Al, element partitioning, and physical properties of the following primary lower mantle minerals (or low-pressure analog minerals): magnesium silicate perovskite (e.g., Aizawa and Yoneda, 2006;Andrault et al, 2007;Auzende et al, 2008;Boffa Ballaran et al, 2012;Carrez et al, 2007a;Cordier et al, 2004;Deng et al, 2008;Dorfman et al, 2012;Ferré et al, 2007;Irifune et al, 2010;Ito and Toriumi, 2010;Jackson and Kung, 2008;Jackson et al, 2005;Jung et al, 2010;Katsura et al, 2009;Lundin et al, 2008;Miyajima et al, 2009;Mosenfelder et al, 2009;Murakami et al, 2007a;Nishio-Hamane et al, 2008;Nishiyama et al, 2007;Ono et al, 2006a,b;Panero et al, 2006;Ricolleau et al, 2009;Saikia et al, 2009;Sakai et al, 2009a;Tange et al, 2009Tange et al, , 2012Vanpeteghem et al, 2006a,b;Xu et al, 2011;Yamazaki et al, 2009), MgO and ferropericlase (e.g., de Koker, 2010;Fukui et al, 2012;Gleason et al, 2011;Jackson et al, 2006;Komabayashi et al, 2010;Marquardt et al, 2009b;Murakami et al, 2009;…”