Preliminary Results from the New Deformation Multi‐Anvil Press at the Photon Factory: Insight into the Creep Strength of Calcium Silicate Perovskite

Thomson, A. P. J.; Nishihara, Yu; Tsujino, Noriyoshi; Hunt, Simon A.; Tsubokawa, Yumiko; Matsukage, Kyoko N.; Yoshino, Takashi; Kubo, Tomoaki; Dobson, David P.

doi:10.1002/9781119526919.ch4

Cited by 2 publications

(1 citation statement)

References 54 publications

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“…D111 experiments were performed at synchrotron beamline NE7A at PF‐AR, KEK, Tsukuba, Japan (Nishihara, Tsujino, et al., 2020; Thomson et al., 2023; Tsujino et al., 2022). Throughout D111 experiments, 7M/2 assemblies were employed, denoting the (Mg,Co)O octahedral pressure medium with 7 mm edge lengths and anvils with 2 mm truncation edge lengths.…”

Section: Methodsmentioning

confidence: 99%

Rheology of Hexagonal Close‐Packed (hcp) Iron

et al. 2023

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The viscosity of hexagonal close‐packed (hcp) Fe is a fundamental property controlling the dynamics of the Earth's inner core. We studied the rheology of hcp‐Fe using high‐pressure and ‐temperature deformation experiments with in situ stress and strain measurements. Experiments were conducted using D111‐type and deformation‐DIA apparatuses at pressures of 16.3–22.6 GPa, temperatures of 423–923 K, and uniaxial strain rates of 1.52 × 10−6 to 8.81 × 10−5 s−1 in conjunction with synchrotron radiation. Experimental results showed that power‐law dislocation creep with a stress exponent of n = 4.0 ± 0.3, activation energy of E* = 240 ± 20 kJ/mol, and activation volume of V* = 1.4 ± 0.2 cm3/mol is dominant deformation mechanism at >∼800 K, whereas a mechanism with power‐law breakdown prevails at lower temperatures. An extrapolation of the power‐law dislocation creep flow law based on homologous temperature scaling suggests the viscosity of hcp‐Fe under inner core conditions is ≥∼1019 Pa s. If this power‐law dislocation creep mechanism is assumed to be the dominant mechanism in the Earth's inner core, the equatorial growth or translation mode mechanism may be the dominant geodynamical mechanism causing the observed inner core structure.

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Section: Methodsmentioning

confidence: 99%

Rheology of Hexagonal Close‐Packed (hcp) Iron

et al. 2023

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Crystallographic Preferred Orientation of Phase D at High Pressure and Temperature: Implications for Seismic Anisotropy in the Mid‐Mantle

Wu,

Nishihara,

Tsujino

2024

JGR Solid Earth

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Seismic anisotropy has been widely observed in the lower mantle transition zone and the uppermost lower mantle near several subducting slabs, which is typically attributed to the crystallographic preferred orientation (CPO) of constituent minerals. In this study, well‐controlled uniaxial and simple shear deformation experiments were conducted on Mg‐endmember phase D and Al‐bearing phase D aggregates at 20 GPa and 500–1,000°C. Strong (0001) fabrics were observed in the uniaxially compressed samples. The CPO from all experiments, including extension and simple shear, indicated that the most active slip systems in phase D were <110>(0001) and <100>(0001), with a dominance of <110>(0001). The calculated seismic velocity suggests that the deformed phase D generates positive radial seismic anisotropy (VSH > VSV) in both subhorizontal shearing and subvertical compression, causing significant shear‐wave splitting time. Our results suggest that the observed seismic anisotropy in the mid‐mantle in several cold subduction zones can be well explained by the presence of deformed phase D.

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Preliminary Results from the New Deformation Multi‐Anvil Press at the Photon Factory: Insight into the Creep Strength of Calcium Silicate Perovskite

Cited by 2 publications

References 54 publications

Rheology of Hexagonal Close‐Packed (hcp) Iron

Rheology of Hexagonal Close‐Packed (hcp) Iron

Crystallographic Preferred Orientation of Phase D at High Pressure and Temperature: Implications for Seismic Anisotropy in the Mid‐Mantle

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