Pressure generation to 65 GPa in a Kawai-type multi-anvil apparatus with tungsten carbide anvils

Ishii, Takayuki; Tsujino, Noriyoshi; Xu, Fang; Liu, Zhaodong; Kawazoe, Takaaki; Yamamoto, Takafumi; Druzhbin, Dmitry; Wang, Lin; Higo, Yuji; Tange, Yoshinori; Yoshino, Takashi; Katsura, Tomoo

doi:10.1080/08957959.2017.1375491

Cited by 30 publications

(13 citation statements)

References 12 publications

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“…The anvil truncations for compressing the pressure medium were 4.0 mm. The anvil faces around the truncation were tapered by 1° to create a wide vertical opening to accommodate the X-rays 29,30 . Supplementary Fig.…”

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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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: 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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“…One-degree tapering was applied on anvil faces around a truncation, allowing a wide vertical opening for X-rays (0.7 mm at a maximum in this study) (Extended Data Fig. 2) and enhancing high-pressure generation 32,33 . The cell assembly for in situ diffraction experiment is drawn in Extended Data Fig.…”

Section: In Situ X-ray Diffraction Experiments Under High Pressure An...mentioning

confidence: 99%

Sharp 660-km discontinuity controlled by extremely narrow binary post-spinel transition

et al. 2019

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The Earth's mantle is characterised by a sharp seismic discontinuity at a depth of 660-km that can provide insights into deep mantle processes. The discontinuity occurs over only 2km -or a pressure difference of 0.1 GPa -and is thought to result from the post-spinel transition, that is, the decomposition of the mineral ringwoodite to bridgmanite plus ferropericlase. Existing high-pressure-temperature experiments have lacked the pressure control required to test whether such sharpness is the result of isochemical phase relations or chemically distinct upper and lower mantle domains. Here, we obtain the isothermal pressure interval of the Mg-Fe binary post-spinel transition by applying advanced multianvil techniques with in situ X-ray diffraction with help of Mg-Fe partition experiments. It is demonstrated that the interval at mantle compositions and temperatures is only 0.01 GPa, corresponding to 250 m. This interval is indistinguishable from zero at seismic frequencies. These results can explain the discontinuity sharpness and provide new support for whole mantle convection in a chemically homogeneous mantle. The present work suggests that distribution of adiabatic vertical flows between the upper and lower mantles can be mapped based on discontinuity sharpness. Main:The 660-km seismic discontinuity (D660) is the boundary between the upper and lower mantles. Seismological studies based on short-period P-wave reflections (Pʹ660Pʹ-PʹPʹ) have demonstrated that D660 is extremely sharp and less than 2 km thick 1 , which is in striking contrast to the 7-km-thick 410-km discontinuity 1 . Understanding the nature of D660 from a perspective of mineral physics provides important clues to open questions about the structure and dynamic processes in the Earth's mantle, such as slab subduction and upwelling of hot plume.Geochemical studies suggest that the Earth's upper mantle consists of ca. 60% atom-

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“…%) and En 95 Cor 5 (Cor: Al 2 O 3 ) compositions (see section S-1 in the Supplementary Information for synthesis details and Table S-1 for their compositions). High pressure and high temperature experiments were conducted using ultra-high pressure multi-anvil technology with carbide anvils (Ishii et al, 2016), and detailed techniques can be found in Figures S-1 o K for 2 and 3 hours. The recovered samples were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA) (see section S-2 in the Supplementary Information for analytical analyses).…”

Section: Experimental Methodsmentioning

confidence: 99%

Rapid decrease of MgAlO2.5 component in bridgmanite with pressure

Liu¹,

Ishii²,

Katsura³

2017

Geochem. Persp. Let.

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The solubility of the MgAlO 2.5 component in bridgmanite was measured at pressures of 27, 35 and 40 GPa and a temperature of 2000 o K using an ultra-high pressure multi-anvil press. Compositional analysis of recovered samples demonstrated that the MgAlO 2.5 component decreases with increasing pressure, and approaches virtually zero at 40 GPa. Above this pressure, the MgAlO 2.5 component, i.e. the oxygen-vacancy substitution, becomes negligible, and Al is incorporated in bridgmanite by the charge-coupled substitution only. These results are supported by the volume change associated with the change from the oxygen-vacancy substitution to charge-coupled substitution. The present result may explain the seismically observed slab stagnation in the mid-lower mantle. Although bridgmanite has been put forward as a potential host for water and argon in the lower mantle by trapping them in oxygen vacancies, such capabilities will rapidly decrease with depth and be lost in regions deeper than 1000 km.

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Pressure generation to 65 GPa in a Kawai-type multi-anvil apparatus with tungsten carbide anvils

Cited by 30 publications

References 12 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

Sharp 660-km discontinuity controlled by extremely narrow binary post-spinel transition

Rapid decrease of MgAlO2.5 component in bridgmanite with pressure

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