Silicon self‐diffusion in wadsleyite: Implications for rheology of the mantle transition zone and subducting plates

Shimojuku, Akira; Kubo, Tomoaki; Ohtani, Eiji; Yurimoto, H.

doi:10.1029/2004gl020002

Cited by 21 publications

(23 citation statements)

References 22 publications

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“…[] at ambient pressure, and other researchers [ Jaoul et al ., ; Houlier et al ., ; Andersson et al ., ; Béjina and Jaoul , ] (data not shown in Figure a). Nevertheless, the thermodynamic wadsleyite (10–20 GPa and 1000–1900 K) and ringwoodite (16–24 GPa and 1000–1900 K) calculations are slightly lower than those experimentally obtained [ Shimojuku et al ., ]. The experimental determinations for Si self‐diffusion in MgSiO 3 perovskite are completely close to each other [ Yamazaki et al ., ; Dobson et al ., ; Xu et al ., ] at 25 GPa.…”

Section: Resultscontrasting

confidence: 61%

Application of the cBΩ model to the calculation of diffusion parameters of Si in silicates

Zhang

Shan

2015

Geochem. Geophys. Geosyst.

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Silicon diffusion in major mantle minerals plays an important role in understanding a number of physical and chemical processes in the Earth's interior. Inspection of existing experimental data reveals linear compensation law between the preexponential factors and the activation energies for Si diffusion in various minerals by focusing on those of geophysical interest. On the basis of the observed compensation relationship, here we propose a thermodynamic model, the so-called cBX model that interconnects point defect parameters with the bulk properties to reproduce the Si self-diffusion coefficients in different rockforming minerals. When the uncertainties are considered, the predicted results show that the temperature and pressure dependences of self-diffusion coefficients concur with existing experimental data and theoretical calculations in most cases.

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Section: Resultscontrasting

confidence: 61%

Application of the cBΩ model to the calculation of diffusion parameters of Si in silicates

Zhang

Shan

2015

Geochem. Geophys. Geosyst.

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“…More recent experimental data by Dohmen et al [2002] showed a much higher activation energy for silicon diffusion in olivine compared to the older data. The new activation energy for olivine is also significantly different from the activation energy of silicon in wadsleyite [ Shimojuku et al , 2004]. However, silicon diffusion in wadsleyite is very similar to diffusivity of silicon in olivine reported by Houlier et al [1990].…”

Section: Applicationsmentioning

confidence: 91%

Modeling petrological geodynamics in the Earth's mantle

Tirone

Ganguly

2009

Geochem Geophys Geosyst

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[1] We have developed an approach that combines principles of fluid dynamics and chemical thermodynamics into a fully coupled scheme to model geodynamic and petrological evolution of the Earth's mantle. Transport equations involving pressure, temperature, velocities, and bulk chemical composition are solved for one or more dynamic phases and interfaced with the thermodynamic solutions for equilibrium mineralogical assemblages and compositions. The mineralogical assemblage and composition are computed on a space-time grid, assuming that local thermodynamic equilibrium is effectively achieved. This approach allows us to simultaneously compute geophysical, geochemical, and petrological properties that can be compared with a large mass of observational data to gain insights into a variety of solid Earth problems and melting phenomena. We describe the salient features of our numerical scheme and the underlying mathematical principles and discuss a few selected applications to petrological and geophysical problems. First, it is shown that during the initial stage of passive spreading of plates, the composition of the melt near Earth's surface is in reasonable agreement with the average major element composition of worldwide flood basalts. Only the silica content from our model is slightly higher that in observational data. The amount of melt produced is somewhat lower than the estimated volumes for extrusive and upper crustal intrusive igneous rocks from large igneous provinces suggesting that an active upwelling of a larger mantle region should be considered in the process. Second, we have modeled a plume upwelling under a moving plate incorporating the effects of mineralogy on the density structure and viscous dissipation on the heat transport equation. The results show how these effects promote mantle instability at the base of the lithosphere. Third, we have considered a mantle convection model with viscosity and density directly related to the local equilibrium mineralogical assemblage. Interesting lateral variations and significant differences in the viscosity structure of the upper and lower mantle are revealed from our model results. The averaged viscosity variations with depth retrieved from our numerical simulations seem to reproduce the main features of the mantle viscosity structure under the Pacific ocean obtained from recent studies based on inversion of seismic data.

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“…In our model, plate motion and plate-boundary migration are generated dynamically without velocity conditions imposed on the plate as our previous studies (Tagawa et al, 2007b;Nakakuki et al, 2008). We introduce the viscosity reduction in the transition-zone and/or the lower-mantle slab because of the grain-size reduction that accompanies the phase transitions at 410-km (Rubie, 1984;Karato, 1989;Riedel and Karato, 1997;Shimojuku et al, 2004;Yamazaki et al, 2005) and 660-km (Ito and Sato, 1991;Karato et al, 1995;Kubo et al, 2000) depths. The importance of the slab plasticity is highlighted in the mechanism that determines the structure and the fate of the subducted plate.…”

Section: Introductionmentioning

confidence: 99%

Dynamical mechanisms controlling formation and avalanche of a stagnant slab

Nakakuki

Tagawa

Iwase

2010

Physics of the Earth and Planetary Interiors

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We performed a numerical study to understand the dynamical mechanism controlling the formation and avalanche of a stagnant slab using two-dimensional dynamical models of the integrated plate-mantle system with freely movable subducting and overriding plates. We examined slab rheology as a mechanism for producing various styles of stagnating or penetrating slabs that interact with the 410-km and 660-km phase transitions. The simulated results with the systematically changed rheological parameters are interpreted using a simple stability analysis that includes the forces acting on the stagnant slab. Slab plasticity that memorizes the shape produced by past deformation generates slab stagnation at various depths around the 660-km phase transition. The slab stagnates even beneath the 660-km phase boundary, with a gentle Clapeyron slope. Feedbacks between trench backward migration and slab deformation promote each other during the slab stagnation stage. Slab viscosity also determines the final state of the subducted slab, that is, it continues stagnation or initiates penetration. A low-viscosity slab can finally penetrate into the lower mantle because the growth time of the Rayleigh-Taylor instability is shorter. After the avalanche, the direction of the trench migration changes depending on the lower mantle slab viscosity.

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Silicon self‐diffusion in wadsleyite: Implications for rheology of the mantle transition zone and subducting plates

Cited by 21 publications

References 22 publications

Application of the cBΩ model to the calculation of diffusion parameters of Si in silicates

Application of the cBΩ model to the calculation of diffusion parameters of Si in silicates

Modeling petrological geodynamics in the Earth's mantle

Dynamical mechanisms controlling formation and avalanche of a stagnant slab

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