Diamond anvil cell deformation of CaSiO3 perovskite up to 49GPa

Miyagi, Lowell; Merkel, Sébastien; Yagi, T.; Sata, Nagayoshi; Ohishi, Yasuo; Wenk, H. R.

doi:10.1016/j.pepi.2008.05.018

Cited by 27 publications

(19 citation statements)

References 40 publications

(66 reference statements)

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“…Texture analyses show that the dominating slip system family (see summary in Figure ) in GePv is {1 1 0}<1 1 0> pc with a <1 0 0> pc type texture in both samples, similar to results on single‐phased CaSiO 3 perovskite by Miyagi et al . []. This family of slip systems consists of three orthogonal sets of slip planes, each containing one slip direction, so that each slip plane and direction pair has an equivalent and opposite slip plane and direction pair, e.g., ( 1 1 0) [ 1 1 0 ] pc versus ( 1 1 0 )[ 1 1 0 ] pc , with identical Schmidt factors.…”

Section: Discussionmentioning

confidence: 99%

High‐pressure, high‐temperature deformation of CaGeO₃ (perovskite)±MgO aggregates: Implications for multiphase rheology of the lower mantle

Wang

Hilairet

Nishiyama

et al. 2013

Geochem Geophys Geosyst

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[1] Sintered polycrystalline ''rocks'' of two-phase aggregate CaGeO 3 perovskite (GePv) þ MgO and single-phase GePv were deformed at pressure, temperature, and strain rates of 4-10 GPa, 600-1200 K, and $1-3 Â 10 À5 s À1 , respectively, with maximum bulk strains up to $20%. The as-synthesized twophase aggregate, produced from the reaction CaMgGeO 4 (olivine) ! GePvþMgO (MgO occupying $28% in volume), possessed a load-bearing framework (LBF) texture indistinguishable from that of (Mg,Fe) 2 SiO 4 ! (Mg,Fe)SiO 3 perovskite þ (Mg,Fe)O reported in previous studies. Stress states of the two phases in the deforming aggregate were evaluated based on systematic distortion of lattice spacings over the entire 360 diffraction azimuth angle. Compared with the single-phase GePv sample, stresses of GePv in the two-phase composite were about 10-20% higher at similar strain and strain rates. Stresses of MgO are about a factor of $2 lower than GePv in the same two-phased rock. Volumetrically averaged bulk stresses in the two samples were therefore virtually identical. Texture analyses showed that both samples deformed by dislocation glide, with the dominant slip systems {1 0 0}<1 1 0> (in cubic setting) for both GePv and MgO. These results show that, at low bulk strains up to $20%, the two-phase aggregate remains a LBF fabric, with rheological properties of GePv controlling those of the bulk. These experimental findings are in quantitative agreement with previous numerical simulations. Implications of the results to the silicate counterparts and dynamics of the lower mantle are discussed.

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Section: Discussionmentioning

confidence: 99%

High‐pressure, high‐temperature deformation of CaGeO₃ (perovskite)±MgO aggregates: Implications for multiphase rheology of the lower mantle

Wang

Hilairet

Nishiyama

et al. 2013

Geochem Geophys Geosyst

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“…Slip systems are inferred by comparing experimental CPOs with textures obtained by VPSC simulations, assuming different slip system activities. Such experiments have been applied to periclase (Stretton et al 2001;Merkel et al 2002;Yamazaki & Karato 2002;Long et al 2006;Lin et al 2009), perovskite (Karato et al 1995;Wenk et al 2004) and post-perovskite (Merkel et al 2006(Merkel et al , 2007Miyagi et al 2009;Walte et al 2009;Hirose et al 2010;Miyagi et al 2010;Okada et al 2010;Nisr et al 2012).…”

Section: Deformation Mechanismsmentioning

confidence: 99%

“…The preferred system for dislocation creep in post-perovskite is more ambiguous: Merkel et al (2006) suggest that a combination of the planes (100) and (110) dominate; Miyagi et al (2009) suggest (010); while Miyagi et al (2010) suggest (001)<100> and (001)<010>. The former two experiments were done on analogue material and measurements might have been obscured by the occurring phase transition Miyagi et al 2011).…”

Section: Deformation Mechanismsmentioning

confidence: 99%

Synthetic seismic anisotropy models within a slab impinging on the core–mantle boundary

Cottaar

McNamara

et al. 2014

Geophysical Journal International

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S U M M A R YThe lowermost few hundreds of kilometres of the Earth's mantle are elastically anisotropic; seismic velocities vary with direction of propagation and polarization. Observations of strong seismic anisotropy correlate with regions where subducted slab material is expected. In this study, we evaluate the hypothesis that crystal preferred orientation (CPO) in a slab, as it impinges on the core-mantle boundary, is the cause of the observed anisotropy. Next, we determine if fast polarization directions seen by shear waves can be mapped to directions of geodynamic flow. This approach is similar to our previous study performed for a 2-D geodynamic model. In this study, we employ a 3-D geodynamic model with temperaturedependent viscosity and kinematic velocity boundary conditions defined at the surface of the Earth to create a broad downwelling slab. Tracers track the deformation that we assume to be accommodated by dislocation creep. We evaluate the models for the presence of perovskite or post-perovskite and for different main slip systems along which dislocation creep may occur in post-perovskite [(100),(010) and (001)]-resulting in four different mineralogical models of CPO. Combining the crystal pole orientations with single crystal elastic constants results in seismically distinguishable models of seismic anisotropy. The models are evaluated against published seismic observations by analysing different anisotropic components: the radial anisotropy, the splitting for (sub-)vertical phases (i.e. azimuthal anisotropy), and the splitting for subhorizontal phases. The patterns in radial anisotropy confirm our earlier results in 2-D. Observations of radial anisotropy and splitting in subhorizontal phases are mostly consistent with our models of post-perovskite with (010)-slip and (001)-slip. Our model of (001)-slip predicts stronger splitting than for (010)-slip for horizontally propagating phases in all directions. The strongest seismic anisotropy in this model occurs where the slab impinges on the core-mantle boundary. The azimuthal anisotropy pattern for (001)-slip shows fast axis directions at the edges of the slab (sub-)parallel to flow directions, suggesting horizontal flows may be mapped out in the lowermost mantle using seismic observations.

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“…for Pv [32,33], PPv [23][24][25], Ca-Pv [34], ferropericlase [35][36][37][38]. Additional information may be obtained from low-pressure analogs, although bonding characteristics are dierent [39,40], and from atomic force calculations over a wide range of pressure-temperature conditions [41][42][43][44].…”

Section: Deformation Mechanismsmentioning

confidence: 99%

A Refined Approach to Model Anisotropy in the Lowermost Mantle

Chandler

Yuan

et al. 2018

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract.Seismic anisotropy in the lowermost mantle has been attributed to texture development during mantle convection. This study models texture evolution in a subducting slab impinging on the core-mantle boundary. Using a 3-dimensional geodynamic model with tracers recording the deformation history, a visco-plastic self-consistent (VPSC) model for polycrystal deformation, and relying on experimentally determined slip systems, aggregate grains with volume fractions of 60% orthorhombic silicate perovskite (MgSiO 3), 20% cubic calcium perovskite (CaSiO3), and 20% cubic ferropericlase ((Mg,Fe)O) were deformed plastically and developed crystal preferred orientation. Forward and reverse perovskite (Pv)-postperovskite (PPv) phase transitions were included by allowing for likely orientation variant selections. Grain orientations, P (compression) and S (shear) wave velocity pole gures were calculated for each phase as well as the aggregate. The results show that dominant (001) slip on PPv can produce strong texture and shear wave anisotropy of 0.01-3.07% with V S H >VSV which agrees with seismological observations in selected areas of the D layer.

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Diamond anvil cell deformation of CaSiO3 perovskite up to 49GPa

Cited by 27 publications

References 40 publications

High‐pressure, high‐temperature deformation of CaGeO₃ (perovskite)±MgO aggregates: Implications for multiphase rheology of the lower mantle

High‐pressure, high‐temperature deformation of CaGeO₃ (perovskite)±MgO aggregates: Implications for multiphase rheology of the lower mantle

Synthetic seismic anisotropy models within a slab impinging on the core–mantle boundary

A Refined Approach to Model Anisotropy in the Lowermost Mantle

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Diamond anvil cell deformation of CaSiO3 perovskite up to 49GPa

Cited by 27 publications

References 40 publications

High‐pressure, high‐temperature deformation of CaGeO3 (perovskite)±MgO aggregates: Implications for multiphase rheology of the lower mantle

High‐pressure, high‐temperature deformation of CaGeO3 (perovskite)±MgO aggregates: Implications for multiphase rheology of the lower mantle

Synthetic seismic anisotropy models within a slab impinging on the core–mantle boundary

A Refined Approach to Model Anisotropy in the Lowermost Mantle

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High‐pressure, high‐temperature deformation of CaGeO₃ (perovskite)±MgO aggregates: Implications for multiphase rheology of the lower mantle

High‐pressure, high‐temperature deformation of CaGeO₃ (perovskite)±MgO aggregates: Implications for multiphase rheology of the lower mantle