Melting experiments on peridotite to lowermost mantle conditions

Tateno, Shigehiko; Hirose, Kei; Ohishi, Yasuo

doi:10.1002/2013jb010616

Cited by 71 publications

(105 citation statements)

References 51 publications

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“…The large difference between the computed and measured results may be largely due to the neglect of the entropy contributions in this study and also due to experimental uncertainties. For comparisons, the measured data for (Mg, Fe)SiO 3 system are 0.3–0.4 at 25 GPa, dropping below 0.1 above 75 GPa1136. Measurements on Al-bearing silicates have been controversial, reporting large values37 such as 0.47 at 110 GPa.…”

Section: Discussionmentioning

confidence: 99%

Solid-liquid density and spin crossovers in (Mg, Fe)O system at deep mantle conditions

Ghosh

Karki

2016

Sci Rep

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The low/ultralow-velocity zones in the Earth’s mantle can be explained by the presence of partial melting, critically depending on density contrast between the melt and surrounding solid mantle. Here, first-principles molecular dynamics simulations of (Mg, Fe) O ferropericlase in the solid and liquid states show that their densities increasingly approach each other as pressure increases. The isochemical density difference between them diminishes from 0.78 (±0.7) g/cm3 at zero pressure (3000 K) to 0.16 (±0.04) g/cm3 at 135 GPa (4000 K) for pure and alloyed compositions containing up to 25% iron. The simulations also predict a high-spin to low-spin transition of iron in the liquid ferropericlase gradually occurring over a pressure interval centered at 55 GPa (4000 K) accompanied by a density increase of 0.14 (±0.02) g/cm3. Temperature tends to widen the transition to higher pressure. The estimated iron partition coefficient between the solid and liquid ferropericlase varies from 0.3 to 0.6 over the pressure range of 23 to 135 GPa. Based on these results, an excess of as low as 5% iron dissolved in the liquid could cause the solid-liquid density crossover at conditions of the lowermost mantle.

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Section: Discussionmentioning

confidence: 99%

Solid-liquid density and spin crossovers in (Mg, Fe)O system at deep mantle conditions

Ghosh

Karki

2016

Sci Rep

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“…

K_{pv} = \frac{x_{1} / x_{2}}{Z_{pv} / (1 - Z_{pv})}

has been measured by a number of experimentalists [ Nomura et al , ; Tateno et al , ]. We use also Mg/Fe partitioning coefficient between melt and ferropericlase measured up to 35 GPa [ Katsura and Ito , ; Ohtani et al , ; Nomura et al , ]

K_{fp} = \frac{x_{1} / x_{2}}{Z_{fp} / (1 - Z_{fp})}

…”

Section: Thermodynamic Modelmentioning

confidence: 99%

“…According to our database, it decreases from 0.5 to less than 0.1 throughout the lower mantle. Experimentally (and in our simulations) the solid phase in equilibrium with the melt is ferropericlase near the top of the lower mantle and bridgmanite above 30 GPa [ Ito et al , ; Fiquet et al , ; Nomura et al , ; Tateno et al , ]. Therefore, near 30 GPa, K p v / K f p should be of order of 0.4.…”

Section: Thermodynamic Modelmentioning

confidence: 99%

Thermodynamics of the MgO‐FeO‐SiO₂system up to 140 GPa: Application to the crystallization of Earth's magma ocean

2015

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At the end of Earth's accretion and after the core‐mantle segregation, the existence of a basal magma ocean at the top of the core‐mantle boundary (CMB) depends on the physical properties of mantle materials at relevant pressure and temperature. Present‐day deep mantle structures such as ultralow‐velocity zones and low‐shear velocity provinces might be directly linked to the still ongoing crystallization of a primordial magma ocean. We provide the first steps toward a self‐consistent thermodynamic model of magma ocean crystallization at high pressure. We build a solid‐liquid thermodynamic database for silicates in the MgO‐FeO‐SiO2 system from 20 GPa to 140 GPa. We use already published chemical potentials for solids, liquid MgO, and SiO2. We derive standard state chemical potential for liquid FeO and mixing relations from various indirect observations. Using this database, we compute the ternary phase diagram in the MgO‐FeO‐SiO2 system as a function of temperature and pressure. We confirm that the melt is lighter than the solid of same composition for all mantle conditions but at thermodynamic equilibrium, the iron‐rich liquid is denser than the solid in the deep mantle. We compute a whole fractional crystallization sequence of the mantle and show that an iron‐rich and fusible layer should be left above the CMB at the end of the crystallization.

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“…A strong partitioning of Fe into the partial melts at lowermost mantle conditions (Tateno et al 2014;Pradhan et al 2015) will make the partially molten regions denser than the surrounding mantle, including the LLSVP material.…”

Section: Compositional Asymmetry Of Plumes and Ultra-low Velocity Zonesmentioning

confidence: 99%

Earth evolution and dynamics—a tribute to Kevin Burke

et al. 2016

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Kevin Burke's original and thought-provoking contributions have been published steadily for the past sixty years, and more than a decade ago he set out to resolve how plate tectonics and mantle plumes interact by proposing a simple conceptual model, which we will refer to as "the Burkian Earth". On the Burkian Earth, mantle plumes take us from the deepest mantle to sub-lithospheric depths, where partial melting occurs, and to the surface, where hotspot lavas erupt today, and where large igneous provinces and kimberlites have erupted episodically in the past. The arrival of a plume head contributes to continental break-up and punctuates plate tectonics by creating and modifying plate boundaries. Conversely, plate tectonics makes an essential contribution to the mantle through subduction. Slabs restore mass to the lowermost mantle and are the triggering mechanism for plumes that rise from the margins of large-scale low shear-wave velocity structures in the lowermost mantle, that Kevin christened TUZO and JASON. Situated just above the core-mantle boundary beneath Africa and the Pacific, these are two stable and antipodal thermochemical piles, which Kevin reasons represent the immediate after-effect of the moon-forming event and the final magma ocean crystallization.

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Melting experiments on peridotite to lowermost mantle conditions

Cited by 71 publications

References 51 publications

Solid-liquid density and spin crossovers in (Mg, Fe)O system at deep mantle conditions

Solid-liquid density and spin crossovers in (Mg, Fe)O system at deep mantle conditions

Thermodynamics of the MgO‐FeO‐SiO₂system up to 140 GPa: Application to the crystallization of Earth's magma ocean

Earth evolution and dynamics—a tribute to Kevin Burke

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Melting experiments on peridotite to lowermost mantle conditions

Cited by 71 publications

References 51 publications

Solid-liquid density and spin crossovers in (Mg, Fe)O system at deep mantle conditions

Solid-liquid density and spin crossovers in (Mg, Fe)O system at deep mantle conditions

Thermodynamics of the MgO‐FeO‐SiO2system up to 140 GPa: Application to the crystallization of Earth's magma ocean

Earth evolution and dynamics—a tribute to Kevin Burke

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Thermodynamics of the MgO‐FeO‐SiO₂system up to 140 GPa: Application to the crystallization of Earth's magma ocean