Phase transition in MgSiO3 perovskite in the earth's lower mantle

Tsuchiya, Taku; Tsuchiya, Jun; Umemoto, Koichiro; Wentzcovitch, Renata M.

doi:10.1016/j.epsl.2004.05.017

Cited by 576 publications

(462 citation statements)

References 27 publications

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“…The variation in the thickness of the D 00 layer for regions with V SH > V SV is controlled by the amount of deposited paleo-slab materials. Recently Tsuchiya et al [2004a] reported a phase transition in MgSiO 3 -perovskite at the lowermost mantle pressure-temperature condition and Post-perovskite MgSiO 3 was anisotropic, producing maximum 10% transverse isotropy [Tsuchiya et al, 2004b]. The oldest subduction may decrease the temperature in the lowermost mantle beneath the Antarctic Ocean.…”

Section: Discussionmentioning

confidence: 99%

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Thick and anisotropic D″ layer beneath Antarctic Ocean

Usui

Hiramatsu

Furumoto

et al. 2005

Geophysical Research Letters

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Waveform modeling and travel times analyses of S, ScS and SKS phases recorded at the broad‐band permanent station SYO in the Antarctic are used to determine the shear wave velocity structure and transverse isotropy in the D″ layer beneath the Antarctic Ocean. The SH wave structure has a discontinuity with the velocity increase of 2.0% at 2550 km. The SV structure is similar to PREM model. The magnitude of the anisotropy is highest at the top of D″ layer and lowest at the core‐mantle boundary. The D″ layer beneath the Antarctic Ocean is significantly thicker than those beneath Alaska and the Caribbean Sea. We attribute this anisotropic D″ layer to paleo‐slab materials. The subduction in and around the Antarctic Ocean has started ∼180 Ma and is the one of the oldest in the world. It has provided a large amount of the slab materials in the lowermost mantle.

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Section: Discussionmentioning

confidence: 99%

“…The oldest subduction may decrease the temperature in the lowermost mantle beneath the Antarctic Ocean. A positive Clapeyron slope of the phase transition in MgSiO 3 perovskite [Tsuchiya et al, 2004a] is a possible cause to control the difference in the thickness of the D 00 layer.…”

Section: Discussionmentioning

confidence: 99%

Thick and anisotropic D″ layer beneath Antarctic Ocean

Usui

Hiramatsu

Furumoto

et al. 2005

Geophysical Research Letters

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“…Circles indicate results at static conditions by Karki and Crain [1998]. Diamonds and squares denote values for MgPv and MgPPv [Tsuchiya et al, 2004a[Tsuchiya et al, , 2004b at static conditions.…”

Section: 1002/2015gl063446mentioning

confidence: 99%

“…The electronic configurations pseudized are 3s 2 3p 6 3d 0 4s 2 for Ca, 3s 2 3p 2 3d 0 for Si, and 2s 2 2p 4 for O. All of these have been well tested in our previous studies [Tsuchiya et al, 2004a[Tsuchiya et al, , 2004b[Tsuchiya et al, , 2005Kawai and Tsuchiya, 2010. The plane wave energy cutoff was set to 50 Ry.…”

Section: Computationmentioning

confidence: 99%

Small shear modulus of cubic CaSiO₃ perovskite

Kawai

Tsuchiya

2015

Geophysical Research Letters

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Ca‐perovskite (CaPv) is considered to be one of the most abundant minerals in the Earth's lower mantle (LM). Furthermore, previous static calculations and mean‐field theory suggest that it has a much larger shear modulus than bridgmanite (MgPv). In this study, the elasticity of cubic CaPv was reinvestigated using the density functional constant‐temperature first principles molecular dynamics method under the correct conditions to simulate its elasticity. Our new results clearly demonstrate that cubic CaPv has comparable bulk and slightly smaller shear moduli than Fe‐bearing MgPv. This is because the boundary condition for the supercell used in this study allows for the rotational phonon motion of SiO6 octahedra under strain, which predominantly affects the decrease in C11 and C44. Acoustic wave velocities determined from the elastic moduli indicate that cubic CaPv has slower velocities and larger densities than Fe‐bearing MgPv and preliminary reference Earth model in the LM. This suggests that if CaPv‐rich material exists, it can accumulate in the lowermost LM and produce a seismically low‐velocity anomaly.

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“…Normconserving pseudopotentials [Troullier and Martins, 1991] have been employed to describe the ionic core potentials of Si, O, and H atoms, whereas Mg pseudopotential is generated by the method of U. von Barth and R. Car (unpublished material) [Karki et al, 2000]. These pseudopotentials have been extensively tested in our previous studies [e.g., Tsuchiya et al, 2004aTsuchiya et al, , 2004b. The irreducible Brillouin zone of a unit cell of hydrous wadsleyite are sampled on a 2 Â 1 Â 2 Monkhorst-Pack mesh [Monkhorst and Pack, 1976].…”

Section: Methodsmentioning

confidence: 99%

First principles investigation of the structural and elastic properties of hydrous wadsleyite under pressure

Tsuchiya

2009

J. Geophys. Res.

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Protons are found to bond to the O1 site to align the OH dipoles along the edges of M3 vacancies. Calculated elastic constants, bulk and shear moduli, are found to decrease almost linearly with increasing water content but to increase linearly with increasing pressure. At 15 GPa and static 0 K condition, incorporation of 3.3 wt % H 2 O into wadsleyite, which corresponds to the maximum solubility of hydrous wadsleyite, reduces V P and V S by about 3.9 and 4.8%, respectively. This indicates that 1 wt % H 2 O hydration of wadsleyite corresponds to the temperature effects on bulk and shear moduli about 430 K (0 GPa) to 340 K (20 GPa) and 350 K (0 GPa) to 290 K (20 GPa), respectively. The transversely isotropic aggregates demonstrate largest positive polarization anisotropy V SH À V SV when the c axis aligns vertically in both dry and wet cases.Citation: Tsuchiya, J., and T. Tsuchiya (2009), First principles investigation of the structural and elastic properties of hydrous wadsleyite under pressure,

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Phase transition in MgSiO3 perovskite in the earth's lower mantle

Cited by 576 publications

References 27 publications

Thick and anisotropic D″ layer beneath Antarctic Ocean

Thick and anisotropic D″ layer beneath Antarctic Ocean

Small shear modulus of cubic CaSiO₃ perovskite

First principles investigation of the structural and elastic properties of hydrous wadsleyite under pressure

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Phase transition in MgSiO3 perovskite in the earth's lower mantle

Cited by 576 publications

References 27 publications

Thick and anisotropic D″ layer beneath Antarctic Ocean

Thick and anisotropic D″ layer beneath Antarctic Ocean

Small shear modulus of cubic CaSiO3 perovskite

First principles investigation of the structural and elastic properties of hydrous wadsleyite under pressure

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Product

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Small shear modulus of cubic CaSiO₃ perovskite