Search results for "lower mantle"

showing 3 items of 3 documents

Lower mantle hydrogen partitioning between periclase and perovskite : a quantum chemical modelling

2016

Abstract Partitioning of hydrogen (often referred to as H2O) between periclase (pe) and perovskite (pvk) at lower mantle conditions (24–80 GPa) was investigated using quantum mechanics, equilibrium reaction thermodynamics and by monitoring two H-incorporation models. One of these (MSWV) was based on replacements provided by Mg2+ ↔ 2H+ and Si4+ ↔ 4H+; while the other (MSWA) relied upon substitutions in 2Mg2+ ↔ Al3+ + H+ and Si4+ ↔ Al3+ + H+. H2O partitioning in these phases was considered in the light of homogeneous (Bulk Silicate Earth; pvk: 75%–pe:16% model contents) and heterogeneous (Layered Mantle; pvk:78%–pe:14% modal contents) mantle geochemical models, which were configured for lower…

010504 meteorology & atmospheric sciencesHydrogenpericlaseAnalytical chemistrySocio-culturalechemistry.chemical_elementengineering.material010502 geochemistry & geophysics01 natural sciencesMantle (geology)chemistry.chemical_compoundGeochemistry and PetrologyOrganic chemistryH2O-partitioningperovskiteEquilibrium constant0105 earth and related environmental sciencesChemistryAb-initio calculationslowermantle; H2O-partitioning; periclase; perovskite.SilicatePartition coefficientlower mantleAnhydrousengineeringPericlaseChemical equilibriumlower mantle H2O-partitioning Ab-initio calculations periclase perovskite
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Aluminium distribution in an Earth's non–primitive lower mantle

2020

The aluminium incorporation mechanism of perovskite was explored by means of quantum mechanics in combination with equilibrium/off-equilibrium thermodynamics under the pressure-temperature conditions of the Earth's lower mantle (from 24 to 80 GPa). Earth's lower mantle was modelled as a geochemically non-primitive object because of an enrichment by 3 wt% of recycled crustal material (MORB component). The compositional modelling takes into account both chondrite and pyrolite reference models. The capacity of perovskite to host Al was modelled through an Al2O3 exchange process in an unconstrained Mg-perovskite + Mg-Al-perovskite + free-Al2O3(corundum) system. Aluminium is globally incorporate…

Materials science010504 meteorology & atmospheric sciencesSocio-culturaleThermodynamicschemistry.chemical_elementCorundumengineering.materialAluminium bearing perovskite010502 geochemistry & geophysicsMole fraction01 natural sciencesPE10_11Aluminium distribution Earth’s lower mantle; aluminium bearing perovskite; pyrolite chondrite reference model; MORB component; enriched lower mantle composition; open system.Aluminium distributionPressure rangeGeochemistry and PetrologyChondriteAluminiumAluminium bearing perovskite; Aluminium distribution; Chondrite reference model; Earth's lower mantle; Enriched lower mantle composition; MORB component; Open system; PyroliteEnriched lower mantle compositionEarth’s lower mantleChemical composition0105 earth and related environmental sciencesEarth's lower mantleDrop (liquid)PyroliteMORB componentchemistryChondrite reference modelOpen systemPyroliteengineering
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Fe-periclase reactivity at Earth's lower mantle conditions: Ab-initio geochemical modelling

2017

Intrinsic and extrinsic stability of the (Mg, Fe) O solid mixture in the Fe-Mg-Si-O system at high P, T conditions relevant to the Earth's mantle is investigated by the combination of quantum mechanical calculations (Hartree-26 Fock/DFT hybrid scheme), cluster expansion techniques and statistical thermodynamics. Iron in the (Mg, Fe) O binary mixture is assumed to be either in the low spin (LS) or in the high spin (HS) state. Un-mixing at solid state is observed only for the LS condition in the 23-42 GPa pressure range, whereas HS does not give rise to un-mixing. LS (Mg, Fe) O un-mixings are shown to be able to incorporate iron by subsolidus reactions with a reservoir of a virtual bridgmanit…

Subsolidus reaction modellingMgO-FeO binary010504 meteorology & atmospheric sciencesSilicate perovskiteLower mantle geochemical heterogeneitiesAnalytical chemistryAb initioLower mantle geochemical heterogeneities MgO-FeO binary Mixing Gibbs energy Pyrolitic geochemical mode Subsolidus reaction modellingMineralogyengineering.material010502 geochemistry & geophysics01 natural sciencesMantle (geology)Geochemistry and PetrologyMixing Gibbs energy0105 earth and related environmental sciencesPyrolitic geochemical modeSettore GEO/06 - MineralogiaPyrolitic geochemical modelAmbientaleDiamondHartreePartition coefficientengineeringPericlaseMgO-FeO binaryPyrolitic geochemical modelLower mantle geochemical heterogeneitiesSubsolidus reaction modellingMixing Gibbs energyGeologyCluster expansion
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