Journal of Next-Generation Research 5.0
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Modèles de calcul des capacités calorifiques des liquides et verres silicatés
No full textInternational audienc
Density calculations for silicate liquids. I revised method for aluminosilicate compositions
No full textInternational audienceEquations are developed for calculating the density of aluminosilicate liquids as a function of composition and temperature. The mean molar volume at reference temperature Tr, is given by , where the summation is taken over all oxide components except A12O3, X stands for mole fraction, terms are constants derived independently from an analysis of volume-composition relations in alumina-free silicate liquids, and is the composition-dependent apparent partial molar volume of Al2O3. The thermal expansion coefficient of aluminosilicate liquids is given by , where terms are constants independent of temperature and composition, and is a composition-dependent term representing the effect of Al2O3 on the thermal expansion. Parameters necessary to calculate the volume of silicate liquids at any temperature T according to V(T) = Vrexp[α(T-Tr)], where Tr = 1400°C have been evaluated by least-square analysis of selected density measurements in aluminosilicate melts. Mean molar volumes of aluminosilicate liquids calculated according to the model equation conform to experimentally measured volumes with a root mean square difference of 0.28 and an average absolute difference of 0.90% for 248 experimental observations. The compositional dependence of is discussed in terms of several possible interpretations of the structural role of Al3+ in aluminosilicate melts
High-pressure and temperature equation of state and calculation of the thermodynamic properties of gaseous carbon dioxide
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Flux de chaleur, production de chaleur et évolution géodynamique récente du Massif Central français
No full textWe investigate in this thesis the possible origin of the high heat flow anomaly observed in the Massif Central (100–110 mW m−2).A detailed study of crustal heat production shows that the radioactive component cannot account for the entire surface anomaly. However, when we remove the integrated radioactive contribution from the surface heat flow, it appears that the anomaly is reduced to a smaller area close to the Cenozoic graben and the volcanic area, with an amplitude of 25–30 mW m−2. This mantle heat flow anomaly is interpreted as a transient component related to a mantle diapir ascent in the Massif Central since the Oligocene, also outlined by several other geological and geophysical studies.A kinematic model of thermal diapir in the mantle can explain this transient anomaly as well as other independent sets of data (gravity anomaly, topography, lithospheric thickness, partial melting) provided the vertical velocity of the ascent is 1 cm yr−1, the width of the diapir 40 km and the depth where it initiates 150 km.Cette thèse évalue les origines possibles du flux géothermique élevé (100-110 mWm-2) observé dans le Massif Central Français.Une étude détaillée de la production de chaleur d'origine radioactive montre que celle-ci ne peut expliquer en totalité le flux de chaleur de surface. Une anomalie de flux de chaleur d'origine profonde est donc mise en évidence, lorsque l'on retranche la production de chaleur intégrée sur l'épaisseur crustale, dans une zone limitée essentiellement aux grabens et volcans d'âge Cénozoïque. L'amplitude de cette anomalie est d'environ 25 à 30 mWm-2, qui s'ajoute au flux mantellique régional. Cette anomalie est interprétée comme étant l'expression d'une composante transitoire du flux géothermique associée à la montée d'un diapir asthénosphérique sous le Massif Central au cours de l'Oligocène, dont plusieurs autres conséquences géologiques ou géophysiques ont été observées.Un modèle thermo-cinématique simulant la remontée diapirique de l'asthénosphère sous le Massif Central Français permet d'évaluer les caractéristiques (largeur, vitesse) qui permettent de rendre compte, simultanément, du flux de chaleur de surface, de la topographie, de l'anomalie gravimétrique ainsi que des taux de fusion partielle à l'origine des différents types de volcanisme observés. Les paramètres les plus appropriés sont une vitesse de remontée d'environ 1 cm/an, sur une largeur de 40 km à partir d'une profondeur d'initiation de 150 km
Heat capacity of liquid silicates: new measurements on NaAISiO8 and K2SiO9
No full textInternational audienceDrop calorimetric measurements of HT-H273 are reported for glassy and liquid albite and potassium tetrasilicate for the temperature interval 600–1500 K. Analysis of these observations as well as data for 13 other stable and supercooled silicate liquids suggests strongly that the isobaric heat capacities of stable and supercooled liquids are equal and thus temperature independent. Available evidence indicates that the isochoric heat capacities of liquid alkali silicates are also temperature independent within present experimental uncertainties
Thermodynamics of liquid silicates, a preliminary report
No full textInternational audienceWe propose a model for the calculation of the thermodynamic properties of silicate liquids. In our model we make use of the Flory-Huggins regular solution formalism for liquid solutions. In this preliminary paper we have limited ourselves to demonstrating that the Flory-Huggins formalism describes satisfactorily the thermodynamic properties of simple liquid silicate solutions, i.e. systems in which only end-member components or solid solutions thereof occur as solid phases and where there is only one well-behaved liquid phase. To compare theoretical results with laboratory observations we need thermodynamic data for liquid silicates. For this reason we have included in this report a review of the available information on the latent heat of fusion of silicate minerals
