scholarly journals Ferrous iron partitioning between magnesium silicate perovskite and ferropericlase and the composition of perovskite in the Earth's lower mantle

2012 ◽  
Vol 117 (B8) ◽  
pp. n/a-n/a ◽  
Author(s):  
Yoichi Nakajima ◽  
Daniel J. Frost ◽  
David C. Rubie
Keyword(s):  
Lower Mantle ◽  
Ferrous Iron ◽  
Magnesium Silicate

scholarly journals Stability of dense hydrous magnesium silicate phase G in the transition zone and the lower mantle.

1998 ◽  
Vol 20 (4) ◽  
pp. 163-169 ◽  
Author(s):  
Eiji OHTANI ◽  
Yasuhiro KUDOH ◽  
Hiroshi NAITO ◽  
Haruo ARASHI
Keyword(s):  
Transition Zone ◽  
Lower Mantle ◽  
Magnesium Silicate ◽  
Silicate Phase

Magnesium silicate perovskite and effect of iron oxidation state on its bulk sound velocity at the conditions of the lower mantle

2014 ◽  
Vol 393 ◽  
pp. 182-186 ◽  
Author(s):  
K. Glazyrin ◽  
T. Boffa Ballaran ◽  
D.J. Frost ◽  
C. McCammon ◽  
A. Kantor ◽  
...  
Keyword(s):  
Sound Velocity ◽  
Oxidation State ◽  
Lower Mantle ◽  
Iron Oxidation ◽  
Magnesium Silicate ◽  
Iron Oxidation State

Effect of Al on the stability of dense hydrous magnesium silicate phases to the uppermost lower mantle: implications for water transportation into the deep mantle

2021 ◽  
Vol 48 (9) ◽  
Author(s):  
Chaowen Xu ◽  
Toru Inoue ◽  
Sho Kakizawa ◽  
Masamichi Noda ◽  
Jing Gao
Keyword(s):  
Lower Mantle ◽  
Magnesium Silicate ◽  
Water Transportation ◽  
Deep Mantle ◽  
The Stability

scholarly journals XANES study of the oxidation state of Cr in lower mantle phases: Periclase and magnesium silicate perovskite

2007 ◽  
Vol 92 (5-6) ◽  
pp. 966-972 ◽  
Author(s):  
S. G. Eeckhout ◽  
N. Bolfan-Casanova ◽  
C. McCammon ◽  
S. Klemme ◽  
E. Amiguet
Keyword(s):  
Oxidation State ◽  
Lower Mantle ◽  
Magnesium Silicate

scholarly journals Ferrous iron partitioning in the lower mantle

2016 ◽  
Vol 257 ◽  
pp. 12-17 ◽  
Author(s):  
Joshua M.R. Muir ◽  
John P. Brodholt
Keyword(s):  
Lower Mantle ◽  
Ferrous Iron

Aluminum in Magnesium Silicate Perovskite: Synthesis and Energetics of Defect Solid Solutions

2002 ◽  
Vol 718 ◽  
Author(s):  
Alexandra Navrotsky ◽  
Mirko Schoenitz ◽  
Hiroshi Kojitani ◽  
Hongwu Xu ◽  
Jianzhong Zhang ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Lower Mantle ◽  
Water Retention ◽  
Magnesium Silicate ◽  
Solution Calorimetry ◽  
Phase Synthesis ◽  
Oxide Melt ◽  
The Earth

AbstractMgSiO3 - rich perovskite is expected to dominate the Earth's lower mantle (pressures > 25 GPa), with iron and aluminum as significant substituents. The incorporation of trivalent ions, M3+, may occur by two competing mechanisms: MgA+ SiB = MA + MB and SiB = AlB + 0.5 VO. Phase synthesis studies show that both substitutions do occur, and the nonstoichiometric or defect substitution is prevalent along the MgSiO3 - MgAlO2.5 join. Oxide melt solution calorimetry has been used to compare the energetics of both substitutions. The stoichiometric substitution, represented by the reaction 0.95 MgSiO3 (perovskite) + 0.05 Al2O3 (corundum) = Mg0.95Al0.10Si0.95O3 (perovskite), has an enthalpy of -0.8±2.2 kJ/mol. The nonstoichiometric reaction, 0.90 MgSiO3 (perovskite) + 0.10 MgO (rocksalt) + 0.05 Al2O3 (corundum) = MgSi0.9Al0.1O2.95 (perovskite) has a small positive enthalpy of 8.5±4.6 kJ/mol. The defect substitution is not prohibitive in enthalpy, entropy, or volume, is favored in perovskite coexisting with magnesiowüstite, and may significantly affect the elasticity, rheology and water retention of silicate perovskite in the Earth.

Stable intermediate-spin ferrous iron in lower-mantle perovskite

2008 ◽  
Vol 1 (10) ◽  
pp. 684-687 ◽  
Author(s):  
C. McCammon ◽  
I. Kantor ◽  
O. Narygina ◽  
J. Rouquette ◽  
U. Ponkratz ◽  
...  
Keyword(s):  
Lower Mantle ◽  
Ferrous Iron ◽  
Stable Intermediate ◽  
Intermediate Spin

Iron Partitioning and Density Changes of Pyrolite in Earth’s Lower Mantle

Science ◽  
2009 ◽  
Vol 327 (5962) ◽  
pp. 193-195 ◽  
Author(s):  
Tetsuo Irifune ◽  
Toru Shinmei ◽  
Catherine A. McCammon ◽  
Nobuyoshi Miyajima ◽  
David C. Rubie ◽  
...  
Keyword(s):  
Partition Coefficient ◽  
Lower Mantle ◽  
Deep Structure ◽  
Spin Transition ◽  
Magnesium Silicate ◽  
Considerable Change ◽  
Model Composition ◽  
Structure And Dynamics ◽  
Composition Of Minerals ◽  
Pressure Phase

Phase transitions and the chemical composition of minerals in Earth’s interior influence geophysical interpretations of its deep structure and dynamics. A pressure-induced spin transition in olivine has been suggested to influence iron partitioning and depletion, resulting in a distinct layered structure in Earth’s lower mantle. For a more realistic mantle composition (pyrolite), we observed a considerable change in the iron-magnesium partition coefficient at about 40 gigapascals that is explained by a spin transition at much lower pressures. However, only a small depletion of iron is observed in the major high-pressure phase (magnesium silicate perovskite), which may be explained by preferential retention of the iron ion Fe3+. Changes in mineral proportions or density are not associated with the change in partition coefficient. The observed density profile agrees well with seismological models, which suggests that pyrolite is a good model composition for the upper to middle parts of the lower mantle.

Stability of dense hydrous magnesium silicate phases and water storage capacity in the transition zone and lower mantle

2001 ◽  
Vol 124 (1-2) ◽  
pp. 105-117 ◽  
Author(s):  
E Ohtani ◽  
M Toma ◽  
K Litasov ◽  
T Kubo ◽  
A Suzuki
Keyword(s):  
Transition Zone ◽  
Lower Mantle ◽  
Storage Capacity ◽  
Water Storage ◽  
Magnesium Silicate ◽  
Water Storage Capacity

scholarly journals Composition and Pressure Effects on Partitioning of Ferrous Iron in Iron-Rich Lower Mantle Heterogeneities

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 512
Author(s):  
Susannah M. Dorfman ◽  
Farhang Nabiei ◽  
Charles-Edouard Boukaré ◽  
Vitali B. Prakapenka ◽  
Marco Cantoni ◽  
...  
Keyword(s):  
Lower Mantle ◽  
Ferrous Iron ◽  
Shear Velocity ◽  
Pressure Effects ◽  
Sio2 Content ◽  
Ex Situ ◽  
Mantle Dynamics ◽  
Mantle Heterogeneities ◽  
Transmission Electron ◽  
Laser Heated

Both seismic observations of dense low shear velocity regions and models of magma ocean crystallization and mantle dynamics support enrichment of iron in Earth’s lowermost mantle. Physical properties of iron-rich lower mantle heterogeneities in the modern Earth depend on distribution of iron between coexisting lower mantle phases (Mg,Fe)O magnesiowüstite, (Mg,Fe)SiO3 bridgmanite, and (Mg,Fe)SiO3 post-perovskite. The partitioning of iron between these phases was investigated in synthetic ferrous-iron-rich olivine compositions (Mg0.55Fe0.45)2SiO4 and (Mg0.28Fe0.72)2SiO4 at lower mantle conditions ranging from 33–128 GPa and 1900–3000 K in the laser-heated diamond anvil cell. The resulting phase assemblages were characterized by a combination of in situ X-ray diffraction and ex situ transmission electron microscopy. The exchange coefficient between bridgmanite and magnesiowüstite decreases with pressure and bulk Fe# and increases with temperature. Thermodynamic modeling determines that incorporation and partitioning of iron in bridgmanite are explained well by excess volume associated with Mg-Fe exchange. Partitioning results are used to model compositions and densities of mantle phase assemblages as a function of pressure, FeO-content and SiO2-content. Unlike average mantle compositions, iron-rich compositions in the mantle exhibit negative dependence of density on SiO2-content at all mantle depths, an important finding for interpretation of deep lower mantle structures.

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