Post-Perovskite Phase Transition in MgSiO
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Murakami, Motohiko; Hirose, Kei; Kawamura, Katsuyuki; Sata, Nagayoshi; Ohishi, Yasuo

doi:10.1126/science.1095932

Cited by 1,254 publications

(774 citation statements)

References 26 publications

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“…Due to its large uncertainties, the phase change from perovskite to post-perovskite was not investigated in this study. This transition may, however, occur in Earth's lowermost mantle just above CMB (Murakami et al 2004;Oganov & Ono 2004). Previous numerical studies suggested that this phase change may have important implications in terms of dynamics and evolution of the Earth's mantle (e.g.…”

Section: O N C L U D I N G Discussionmentioning

confidence: 96%

The stability and structure of primordial reservoirs in the lower mantle: insights from models of thermochemical convection in three-dimensional spherical geometry

Deschamps

Tackley

2014

Geophysical Journal International

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S U M M A R YLarge-scale chemical lateral heterogeneities are inferred in the Earth's lowermost mantle by seismological studies. We explore the model space of thermochemical convection that can maintain reservoirs of dense material for a long period of time, by using similar analysis in 3-D spherical geometry. In this study, we focus on the parameters thought to be important in controlling the stability and structure of primordial dense reservoirs in the lower mantle, including the chemical density contrast between the primordial dense material and the regular mantle material (buoyancy ratio), thermal and chemical viscosity contrasts, volume fraction of primordial dense material and the Clapeyron slope of the phase transition at 660 km depth. We find that most of the findings from the 3-D Cartesian study still apply to 3-D spherical cases after slight modifications. Varying buoyancy ratio leads to different flow patterns, from rapid upwelling to stable layering; and large thermal viscosity contrasts are required to generate long wavelength chemical structures in the lower mantle. Chemical viscosity contrasts in a reasonable range have a second-order role in modifying the stability of the dense anomalies. The volume fraction of the initial primordial dense material does not effect the results with large thermal viscosity contrasts, but has significant effects on calculations with intermediate and small thermal viscosity contrasts. The volume fraction of dense material at which the flow pattern changes from unstable to stable depends on buoyancy ratio and thermal viscosity contrast. An endothermic phase transition at 660 km depth acts as a 'filter' allowing cold slabs to penetrate while blocking most of the dense material from penetrating to the upper mantle.

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Section: O N C L U D I N G Discussionmentioning

confidence: 96%

The stability and structure of primordial reservoirs in the lower mantle: insights from models of thermochemical convection in three-dimensional spherical geometry

Deschamps

Tackley

2014

Geophysical Journal International

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“…Recent developments in mineral physics, which are not accounted for in this study, may complicate the interpretation of seismic information, and modify our inferences. Murakami et al (2004) reported a new phase transition from perovskite to post-perovskite around 2700 km. We did preliminary tests using available thermo-elastic data for postperovskite (Tsuchiya et al, 2004a,b), but we did not find any dramatic differences compared to the sensitivities plotted in Figure 4.…”

Section: Discussionmentioning

confidence: 99%

Thermo-Chemical Structure of the Lower Mantle: Seismological Evidence and Consequences for Geodynamics

Deschamps

Trampert

Tackley

2007

Superplumes: Beyond Plate Tectonics

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We combine recent progress in seismic tomography and numerical modeling of thermochemical convection to infer robust features on mantle structure and dynamics. First, we separate the observed density anomalies into their thermal and compositional contributions. The tomographic maps of thermo-chemical variations were computed using a new approach that combines a careful equation of state modeling of the lower mantle, independent constraints on density from probabilistic tomography, and a full statistical treatment for uncertainties analyses. We then test models of thermo-chemical convection against these density components. We compute synthetic anomalies of thermal and compositional density from models of thermo-chemical convection calculated with the anelastic approximation. These synthetic distributions are filtered to make meaningful comparisons with the observed density anomalies. Our comparisons suggest that a stable layer (i.e., that no domes or piles are generated from it) of dense material with buoyancy ratio B ≥ 0.3 is unlikely to be present at the bottom of the mantle. Models of piles entrained upwards from a dense, but unstable layer with buoyancy ratio B ∼ 0.2, explain the observation significantly better, but discrepancies remain at the top of the lower mantle. These discrepancies could be linked to the deflection of slabs around 1000 km, or to the phase transformation at 670 km, not included yet in the thermo-chemical calculations.

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“…Even for MnSiO 3 the mixture of MnO + SiO 2 may be favored compared to perovskite because Mn 2+ with five 3d electrons at the octahedral site also has a large volume reduction by the high spin -low spin transition. and CaIrO 3 , transform to the CaIrO 3 -type post-perovskite structure (Murakami et al, 2004;Oganov and Ono, 2004;Hirose and Fujita, 2005;Tateno et al, 2006). In this diagram, the compounds marked by solid symbols mean that their distortions increase with pressure, while the compounds marked by open symbols mean that their distortions decrease with pressure (Tateno et al, 2006).…”

Section: Stability Of the Perovskite Structure In Fesio 3 Mnsio 3 Amentioning

confidence: 99%

Stability of the perovskite structure and possibility of the transition to the post-perovskite structure in CaSiO3, FeSiO3, MnSiO3 and CoSiO3

Fujino

Nishio–Hamane

Suzuki

et al. 2009

Physics of the Earth and Planetary Interiors

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High pressure and high temperature experiments on CaSiO 3 , FeSiO 3 , MnSiO 3 and CoSiO 3 using a laser-heated diamond anvil cell combined with synchrotron X-ray diffraction were conducted to explore the perovskite structure of these compounds and the transition to the post-perovskite structure. The experimental results revealed that MnSiO 3 has a perovskite structure from relatively low pressure (ca. 20 GPa) similarly to CaSiO 3 , while the stable forms of FeSiO 3 and CoSiO 3 are mixtures of mono-oxide (NaCl structure) + high pressure polymorph of SiO 2 even at very high pressure and temperature (149 GPa and 1800 K for FeSiO 3 and 79 GPa and 2000 K for CoSiO 3 ). This strongly suggests that the crystal field stabilization energy (CFSE) of Fe 2+ with six 3d electrons and Co 2+ with seven 3d electrons at the octahedral site of mono-oxides favors a mixture of mono-oxide + SiO 2 over perovskite where Fe 2+ and Co 2+ would occupy the distorted dodecahedral sites having a smaller CFSE (Mn 2+ has five 3d electrons and has no CFSE).The structural characteristics that the orthorhombic distortion of MnSiO 3 perovskite decreases with pressure and the tolerance factor of CaSiO 3 perovskite (0.99) is far from the orthorhombic range suggest that both MnSiO 3 and CaSiO 3 perovskites will not transform to the CaIrO 3 -type post-perovskite structure even at the Earth's core-mantle boundary conditions, although CaSiO 3 perovskite has a potentiality to transform to the CaIrO 3 -type post-perovskite structure at still higher pressure as long as another type of transformation does not occur.

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Post-Perovskite Phase Transition in MgSiO ₃

Cited by 1,254 publications

References 26 publications

The stability and structure of primordial reservoirs in the lower mantle: insights from models of thermochemical convection in three-dimensional spherical geometry

The stability and structure of primordial reservoirs in the lower mantle: insights from models of thermochemical convection in three-dimensional spherical geometry

Thermo-Chemical Structure of the Lower Mantle: Seismological Evidence and Consequences for Geodynamics

Stability of the perovskite structure and possibility of the transition to the post-perovskite structure in CaSiO3, FeSiO3, MnSiO3 and CoSiO3

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Post-Perovskite Phase Transition in MgSiO 3

Cited by 1,254 publications

References 26 publications

The stability and structure of primordial reservoirs in the lower mantle: insights from models of thermochemical convection in three-dimensional spherical geometry

The stability and structure of primordial reservoirs in the lower mantle: insights from models of thermochemical convection in three-dimensional spherical geometry

Thermo-Chemical Structure of the Lower Mantle: Seismological Evidence and Consequences for Geodynamics

Stability of the perovskite structure and possibility of the transition to the post-perovskite structure in CaSiO3, FeSiO3, MnSiO3 and CoSiO3

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Post-Perovskite Phase Transition in MgSiO ₃