The univariant curve liquid = forsterite + anorthite + diopside in the system CMAS at 1 bar: solid solutions and melt structure

Libourel, G.; Boivin, Pierre; Biggar, G. M.

doi:10.1007/bf00371084

Cited by 40 publications

(23 citation statements)

References 19 publications

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“…4), the scatter in compositions suggests an uncertainty closer to ±0.01. At 1 bar we may make an interlaboratory comparison between the estimates of Presnall et al (1979), Longhi (1987) and Libourel et al. (1989), and find a greater discrepancy in w , closer to ±0.03, which should perhaps serve as a conservative uncertainty estimate.…”

Section: Melt Model Calibration: Outcomementioning

confidence: 94%

“…While forsterite–monticellite solid solution has been investigated at ≤10 kbar by Warner & Luth (1973), the non‐stoichiometry of anorthite and silica in equilibrium with the pyroxenes is too poorly constrained as a function of pressure and temperature to be modelled properly. To evaluate this omission, a simplistic anorthite solid solution model based on the compositions of Libourel et al. (1989) and a forsterite–monticellite model fitted to the data of Warner & Luth (1973) were used in test calculations, but they only affected the calculated pressures of invariant points on the lherzolite solidus by a few tenths of a kilobar.…”

Section: Solid Models Used In Calculationsmentioning

confidence: 99%

“…Data are from Presnall et al. (1979), Longhi (1987) and Libourel et al. (1989) at 1 bar, Herzberg & Zhang (1997) at 50 kbar and the Dallas group (see text).…”

Section: Melt Model Calibration: Outcomementioning

confidence: 99%

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A thermodynamic model for silicate melt in CaO–MgO–Al₂O₃–SiO₂ to 50 kbar and 1800 °C

Green¹,

Holland²,

Powell³

2012

Journal Metamorphic Geology

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A fully thermodynamic model for mafic melt in CaO–MgO–Al2O3–SiO2 (CMAS) has been calibrated, for calculation of melting equilibria in the pressure range 0–50 kbar. It is intended as a preliminary step towards a large‐system melt model, suitable for exploring melting, melt loss and crystallization processes in a wide range of natural rock compositions. Calibration was performed with attention to the model's behaviour in its compositional subsystems, as a rigorous test of model structure and parameterization. The model is consistent with the latest Holland & Powell thermodynamic data set, and can therefore be used to calculate phase relations in conjunction with the many solid‐phase activity–composition models written for the data set. Model calculations successfully reproduce experimental melting reactions in CMAS spinel lherzolite and garnet lherzolite assemblages, as well as sapphirine‐ and kyanite‐bearing assemblages, at moderate to high pressure. Thermodynamically sensitive features, such as thermal divides are also recovered. However, some changes to the model structure will be required before the model can describe the full range of mafic and ultramafic melt compositions known from experiment at low pressures.

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Section: Melt Model Calibration: Outcomementioning

confidence: 94%

Section: Solid Models Used In Calculationsmentioning

confidence: 99%

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A thermodynamic model for silicate melt in CaO–MgO–Al₂O₃–SiO₂ to 50 kbar and 1800 °C

Green¹,

Holland²,

Powell³

2012

Journal Metamorphic Geology

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“…Forsterite and anorthite were modelled as pure phases. In reality, forsterite is known to show minor solid solution towards monticellite up to at least 10 kbar (Warner & Luth, 1973), while anorthite at 1 bar and ∼1250 °C can be described in terms of the components CaAl 2 Si 2 O 8 , Si 4 O 8 , CaMgSi 3 O 8 and MgAl 2 Si 2 O 8 (Libourel et al. , 1989); however, the compositions of these phases were not reported in the studies used for model calibration at ≥10 kbar.…”

Section: Model Structure and Fitting Methodsmentioning

confidence: 99%

Garnet and spinel lherzolite assemblages in MgO–Al₂O₃–SiO₂ and CaO–MgO–Al₂O₃–SiO₂: thermodynamic models and an experimental conflict

Green

Holland

Powell

et al. 2012

Journal Metamorphic Geology

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The recent publication of an updated thermodynamic dataset for petrological calculations provides an opportunity to illustrate the relationship between experimental data and the dataset, in the context of a new set of activity–composition models for several key minerals. These models represent orthopyroxene, clinopyroxene and garnet in the system CaO–MgO–Al2O3–SiO2 (CMAS), and are valid up to 50 kbar and at least 1800 °C; they are the first high‐temperature models for these phases to be developed for the Holland & Powell dataset. The models are calibrated with reference to phase‐relation data in the subsystems CaO–MgO–SiO2 (CMS) and MgO–Al2O3–SiO2 (MAS), and will themselves form the basis of models in larger systems, suitable for calculating phase equilibria in the crust and mantle. In the course of calibrating the models, it was necessary to consider the reaction orthopyroxene + clinopyroxene + spinel = garnet + forsterite in CMAS, representing a univariant transition between simple spinel and garnet lherzolite assemblages. The high‐temperature segment of this reaction has been much disputed. We offer a powerful thermodynamic argument relating this reaction to the equivalent reaction in MAS, that forces us to choose between good model fits to the data in MAS or to the more recent data in CMAS. We favour the fit to the MAS data, preserving conformity with a large body of experimental and thermodynamic data that are incorporated as constraints on the activity–composition modelling via the internally consistent thermodynamic dataset.

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“…The selected CMAS composition (Table 1) is the 1 atm anorthite-diopside eutectic composition (EDiAn), frequently used in the literature as a proxy of basaltic magmas (see also Libourel et al, 1989;O'Neill, 2005;Borisov, 2008Borisov, , 2009. To ascertain the time scale for equilibrium, experiments were performed at 1400°C for durations varying from 1 to 100 h. (Bowen, 1928(Bowen, , 1945Slag Atlas, 1995).…”

Section: Attainment Of Equilibrium and Equilibrium Valuementioning

confidence: 99%

Na2O solubility in CaO–MgO–SiO2 melts

Mathieu

Libourel

Deloule

et al. 2011

Geochimica et Cosmochimica Acta

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The univariant curve liquid = forsterite + anorthite + diopside in the system CMAS at 1 bar: solid solutions and melt structure

Cited by 40 publications

References 19 publications

A thermodynamic model for silicate melt in CaO–MgO–Al₂O₃–SiO₂ to 50 kbar and 1800 °C

A thermodynamic model for silicate melt in CaO–MgO–Al₂O₃–SiO₂ to 50 kbar and 1800 °C

Garnet and spinel lherzolite assemblages in MgO–Al₂O₃–SiO₂ and CaO–MgO–Al₂O₃–SiO₂: thermodynamic models and an experimental conflict

Na2O solubility in CaO–MgO–SiO2 melts

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The univariant curve liquid = forsterite + anorthite + diopside in the system CMAS at 1 bar: solid solutions and melt structure

Cited by 40 publications

References 19 publications

A thermodynamic model for silicate melt in CaO–MgO–Al2O3–SiO2 to 50 kbar and 1800 °C

A thermodynamic model for silicate melt in CaO–MgO–Al2O3–SiO2 to 50 kbar and 1800 °C

Garnet and spinel lherzolite assemblages in MgO–Al2O3–SiO2 and CaO–MgO–Al2O3–SiO2: thermodynamic models and an experimental conflict

Na2O solubility in CaO–MgO–SiO2 melts

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Product

Resources

About

A thermodynamic model for silicate melt in CaO–MgO–Al₂O₃–SiO₂ to 50 kbar and 1800 °C

A thermodynamic model for silicate melt in CaO–MgO–Al₂O₃–SiO₂ to 50 kbar and 1800 °C

Garnet and spinel lherzolite assemblages in MgO–Al₂O₃–SiO₂ and CaO–MgO–Al₂O₃–SiO₂: thermodynamic models and an experimental conflict