Determination of the phase boundary between ilmenite and perovskite in MgSiO 3 by in situ X-ray diffraction and quench experiments

Kuroda, Koji; Irifune, Tetsuo; Inoue, Toru; Nishiyama, Norimasa; Miyashita, M.; Funakoshi, K.; Utsumi, Wataru

doi:10.1007/s002690000096

Cited by 44 publications

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“…5). Each phase of bridgmanite and periclase was itself stable at the pressures investigated 4,31,33 , and contiguous bridgmanite and periclase grains formed ringwoodite only around the grain boundary region in the reversal reaction because of limited diffusivities of the constituent elements, resulting in bridgmanite and periclase grains remaining in the sample. This separation of the bridgmanite and periclase grains impeded completion of the ringwoodite formation.…”

Section: Methodsmentioning

confidence: 96%

“…After remaining at the target temperature for 0.5–2 hr, the samples were quenched by cutting the electric power to the heater and allowed to decompress slowly; even so, avoiding blowout proved impossible. Because the akimotoite-to-bridgmanite transition is kinetically faster than the ringwoodite formation from bridgmanite + periclase 2,3,31,32 , the mineral assemblage before the reverse post-spinel transition should be ringwoodite + bridgmanite + periclase, causing the reaction not from akimotoite + periclase but from bridgmanite + periclase to ringwoodite. Therefore, we successfully conducted both the normal and reversal experiments at 1700 K in this run procedure.…”

Section: Methodsmentioning

confidence: 99%

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Complete agreement of the post-spinel transition with the 660-km seismic discontinuity

Ishii

Rong

Fei

et al. 2018

Sci Rep

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The 660-km seismic discontinuity, which is a significant structure in the Earth’s mantle, is generally interpreted as the post-spinel transition, as indicated by the decomposition of ringwoodite to bridgmanite + ferropericlase. All precise high-pressure and high-temperature experiments nevertheless report 0.5–2 GPa lower transition pressures than those expected at the discontinuity depth (i.e. 23.4 GPa). These results are inconsistent with the post-spinel transition hypothesis and, therefore, do not support widely accepted models of mantle composition such as the pyrolite and CI chondrite models. Here, we present new experimental data showing post-spinel transition pressures in complete agreement with the 660-km discontinuity depth obtained by high-resolution in situ X-ray diffraction in a large-volume high-pressure apparatus with a tightly controlled sample pressure. These data affirm the applicability of the prevailing mantle models. We infer that the apparently lower pressures reported by previous studies are experimental artefacts due to the pressure drop upon heating. The present results indicate the necessity of reinvestigating the position of mantle mineral phase boundaries previously obtained by in situ X-ray diffraction in high-pressure–temperature apparatuses.

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Section: Methodsmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

Complete agreement of the post-spinel transition with the 660-km seismic discontinuity

Ishii

Rong

Fei

et al. 2018

Sci Rep

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“…Gold is important metal in Earth science, because its pressure‐volume‐temperature ( P ‐ V ‐ T ) equation of state (EOS) is the most frequently used pressure calibration standard for in situ high‐pressure and high‐temperature experiments [ Mao et al , 1991; Fei et al , 1992; Meng et al , 1994; Funamori et al , 1996; Irifune et al , 1998; Kuroda et al , 2000; Hirose et al , 2001a, 2001b; Ono et al , 2001]. The characteristic properties of gold, its low rigidity and chemical stability, make it particularly suitable for this role [ Tsuchiya and Kawamura , 2002a].…”

Section: Introductionmentioning

confidence: 99%

First‐principles prediction of the P‐V‐T equation of state of gold and the 660‐km discontinuity in Earth's mantle

2003

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[1] The P-V-T equation of state (EOS) of gold is the most frequently used pressure calibration standard in high-P-T in situ experiments. Empirically proposed EOS models, however, severely scatter under high-P-T conditions, which is a serious problem for studies of the deep Earth. In this study, the EOS of gold is predicted using a first-principles electronic structure calculation method without any empirical parameters. The calculated thermoelastic properties of gold compare favorably to experimental data at ambient conditions so that B T0 and B 0 T0 are 166.7 GPa and 6.12, respectively. Up to V/V a = 0.7, the calculated Grüneisen parameter of gold depends on volume according to the function g/g a = (V/V a ) z with g a of 3.16 and z of 2.15. On the basis of these data, the validity of previous EOS models is discussed. It is found that the present ab initio EOS provides a 1.3 GPa higher pressure than Anderson's scale at 23 GPa and 1800 K and largely reduces the discrepancy observed between conditions at the transition of Mg 2 SiO 4 and the 660-km seismic discontinuity. However, a discrepancy of about 0.7 GPa still remains between the 660-km discontinuity and the postspinel transition.

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“…At each P-T condition, phases present were identified with the diffraction pattern, and the pressure was calculated based on the volume changes in Au using the equation ofstateby Anderson etal [1989]. Further details of the experimental setup and procedures are described elsewhere [Irifune et al, 1998;Kuroda et al, 2000].…”

Section: Methodsmentioning

confidence: 99%

High‐pressure phase transformation in CaMgSi₂O₆ and implications for origin of ultra‐deep diamond inclusions

Irifune

Miyashita

Inoue

et al. 2000

Geophysical Research Letters

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Determination of the phase boundary between ilmenite and perovskite in MgSiO 3 by in situ X-ray diffraction and quench experiments

Cited by 44 publications

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Complete agreement of the post-spinel transition with the 660-km seismic discontinuity

Complete agreement of the post-spinel transition with the 660-km seismic discontinuity

First‐principles prediction of the P‐V‐T equation of state of gold and the 660‐km discontinuity in Earth's mantle

High‐pressure phase transformation in CaMgSi₂O₆ and implications for origin of ultra‐deep diamond inclusions

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Determination of the phase boundary between ilmenite and perovskite in MgSiO 3 by in situ X-ray diffraction and quench experiments

Cited by 44 publications

References 0 publications

Complete agreement of the post-spinel transition with the 660-km seismic discontinuity

Complete agreement of the post-spinel transition with the 660-km seismic discontinuity

First‐principles prediction of the P‐V‐T equation of state of gold and the 660‐km discontinuity in Earth's mantle

High‐pressure phase transformation in CaMgSi2O6 and implications for origin of ultra‐deep diamond inclusions

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High‐pressure phase transformation in CaMgSi₂O₆ and implications for origin of ultra‐deep diamond inclusions