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Andradite

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Gregor Markl – 1st expert on this subject based on the ideXlab platform

  • The effect of titanite and other HFSE-rich mineral (Ti-bearing Andradite, zircon, eudialyte) fractionation on the geochemical evolution of silicate melts
    Chemical Geology, 2020
    Co-Authors: Michael A W Marks, Ian M Coulson, Julian Schilling, Dorrit E Jacob, Axel K Schmitt, Gregor Markl

    Abstract:

    We present trace element data for HFSE-rich minerals (titanite, eudialyte, Ti-bearing Andradite, zircon) from plutonic rocks of the Eocene Tamazeght complex, High Atlas Mountains, Morocco. In most lithologies significant amounts of titanite are present and as such, titanite fractionation played a major role in the evolution of the HFSE budget of the whole complex. By combining our data with published titanite-melt partition coefficients we explore the effects of titanite fractionation on the evolution of geochemical parameters (Zr/Hf, Nb/Ta, La/Lu and Th/U ratios) during differentiation of silicate melts in detail. Based upon this, we further discuss the genetic relationships between the various rock types present in the Tamazeght complex and show that the above-mentioned element ratios can potentially be useful for distinguishing geochemically distinct melt reservoirs within a given plutonic rock suite. Zircon, eudialyte and Ti-bearing Andradite are generally rare or are restricted to localized rock units. Despite their scarcity, each of them can have a significant effect upon the HFSE budget in their evolving magmas. Here, we derive first estimations of eudialyte-melt partition coefficients for REE. Application of these data to eudialyte-bearing rocks of the Ilímaussaq complex (South Greenland), and comparing the results to published estimations for the parental melts of these rocks yields consistent results and demonstrates the reliability of our estimations.20 page(s

  • the effect of titanite and other hfse rich mineral ti bearing Andradite zircon eudialyte fractionation on the geochemical evolution of silicate melts
    Chemical Geology, 2008
    Co-Authors: Michael A W Marks, Ian M Coulson, Julian Schilling, Dorrit E Jacob, Axel K Schmitt, Gregor Markl

    Abstract:

    Abstract We present trace element data for HFSE-rich minerals (titanite, eudialyte, Ti-bearing Andradite, zircon) from plutonic rocks of the Eocene Tamazeght complex, High Atlas Mountains, Morocco. In most lithologies significant amounts of titanite are present and as such, titanite fractionation played a major role in the evolution of the HFSE budget of the whole complex. By combining our data with published titanite–melt partition coefficients we explore the effects of titanite fractionation on the evolution of geochemical parameters (Zr/Hf, Nb/Ta, La/Lu and Th/U ratios) during differentiation of silicate melts in detail. Based upon this, we further discuss the genetic relationships between the various rock types present in the Tamazeght complex and show that the above-mentioned element ratios can potentially be useful for distinguishing geochemically distinct melt reservoirs within a given plutonic rock suite. Zircon, eudialyte and Ti-bearing Andradite are generally rare or are restricted to localized rock units. Despite their scarcity, each of them can have a significant effect upon the HFSE budget in their evolving magmas. Here, we derive first estimations of eudialyte–melt partition coefficients for REE. Application of these data to eudialyte-bearing rocks of the Ilimaussaq complex (South Greenland), and comparing the results to published estimations for the parental melts of these rocks yields consistent results and demonstrates the reliability of our estimations.

Ian M Coulson – 2nd expert on this subject based on the ideXlab platform

  • The effect of titanite and other HFSE-rich mineral (Ti-bearing Andradite, zircon, eudialyte) fractionation on the geochemical evolution of silicate melts
    Chemical Geology, 2020
    Co-Authors: Michael A W Marks, Ian M Coulson, Julian Schilling, Dorrit E Jacob, Axel K Schmitt, Gregor Markl

    Abstract:

    We present trace element data for HFSE-rich minerals (titanite, eudialyte, Ti-bearing Andradite, zircon) from plutonic rocks of the Eocene Tamazeght complex, High Atlas Mountains, Morocco. In most lithologies significant amounts of titanite are present and as such, titanite fractionation played a major role in the evolution of the HFSE budget of the whole complex. By combining our data with published titanite-melt partition coefficients we explore the effects of titanite fractionation on the evolution of geochemical parameters (Zr/Hf, Nb/Ta, La/Lu and Th/U ratios) during differentiation of silicate melts in detail. Based upon this, we further discuss the genetic relationships between the various rock types present in the Tamazeght complex and show that the above-mentioned element ratios can potentially be useful for distinguishing geochemically distinct melt reservoirs within a given plutonic rock suite. Zircon, eudialyte and Ti-bearing Andradite are generally rare or are restricted to localized rock units. Despite their scarcity, each of them can have a significant effect upon the HFSE budget in their evolving magmas. Here, we derive first estimations of eudialyte-melt partition coefficients for REE. Application of these data to eudialyte-bearing rocks of the Ilímaussaq complex (South Greenland), and comparing the results to published estimations for the parental melts of these rocks yields consistent results and demonstrates the reliability of our estimations.20 page(s

  • the effect of titanite and other hfse rich mineral ti bearing Andradite zircon eudialyte fractionation on the geochemical evolution of silicate melts
    Chemical Geology, 2008
    Co-Authors: Michael A W Marks, Ian M Coulson, Julian Schilling, Dorrit E Jacob, Axel K Schmitt, Gregor Markl

    Abstract:

    Abstract We present trace element data for HFSE-rich minerals (titanite, eudialyte, Ti-bearing Andradite, zircon) from plutonic rocks of the Eocene Tamazeght complex, High Atlas Mountains, Morocco. In most lithologies significant amounts of titanite are present and as such, titanite fractionation played a major role in the evolution of the HFSE budget of the whole complex. By combining our data with published titanite–melt partition coefficients we explore the effects of titanite fractionation on the evolution of geochemical parameters (Zr/Hf, Nb/Ta, La/Lu and Th/U ratios) during differentiation of silicate melts in detail. Based upon this, we further discuss the genetic relationships between the various rock types present in the Tamazeght complex and show that the above-mentioned element ratios can potentially be useful for distinguishing geochemically distinct melt reservoirs within a given plutonic rock suite. Zircon, eudialyte and Ti-bearing Andradite are generally rare or are restricted to localized rock units. Despite their scarcity, each of them can have a significant effect upon the HFSE budget in their evolving magmas. Here, we derive first estimations of eudialyte–melt partition coefficients for REE. Application of these data to eudialyte-bearing rocks of the Ilimaussaq complex (South Greenland), and comparing the results to published estimations for the parental melts of these rocks yields consistent results and demonstrates the reliability of our estimations.

Roberto Dovesi – 3rd expert on this subject based on the ideXlab platform

  • elasticity of grossular Andradite solid solution an ab initio investigation
    Physical Chemistry Chemical Physics, 2014
    Co-Authors: Valentina Lacivita, Philippe Darco, Roberto Dovesi, Alessandro Erba

    Abstract:

    Grossular and Andradite are garnet end-members stable under upper mantle conditions. We perform ab initio simulations to investigate the dependence of the bulk modulus on chemical composition of the grossular–Andradite solid solution, Ca3Fe2−2xAl2x(SiO4)3. All-electron local basis sets of Gaussian-type orbitals and the hybrid B3LYP density functional are used. Our calculations predict a linear modulus-composition trend, in contrast to previous conjectures based on “heterogeneous” experimental measurements. We estimate the largest deviation from linearity to be about 0.5 GPa under ambient conditions, and to progressively reduce to less than 0.2 GPa at pressure P = 20 GPa. The bulk modulus is computed over the whole composition range 0 ≤ x ≤ 1 following two independent approaches: fitting energy–volume data to an equation-of-state and calculating elastic tensors. Results from the two methods are in perfect agreement, assuring consistency and high numerical accuracy of the adopted algorithms.

  • anomalous birefringence in Andradite grossular solid solutions a quantum mechanical approach
    Pacific Rim Conference on Multimedia, 2013
    Co-Authors: Valentina Lacivita, Philippe Darco, Roberto Orlando, Roberto Dovesi, Alessio Meyer

    Abstract:

    The static linear optical properties (refractive indices, birefringence and axial angle) of Andradite–grossular (Ca3Fe2Si3O12–Ca3Al2Si3O12) solid solutions have been computed at the ab initio quantum-mechanical level through the Coupled Perturbed Kohn–Sham scheme, using an all-electron Gaussian-type basis set. Geometry relaxation after substitution of 1–8 Al for Fe atoms in the primitive cell of Andradite yields 23 non-equivalent configurations ranging from cubic to triclinic symmetry. Refractive indices vary quite regularly between the Andradite (1.860) and grossular (1.671) end-members; the birefringence δ and the axial angle 2V at intermediate compositions can be as large as 0.02° and 89°, respectively. Comparison with experiments suffers from inhomogeneities and impurities of natural samples; however, semi-quantitative agreement is observed.

  • Anomalous birefringence in Andradite–grossular solid solutions: a quantum-mechanical approach
    Physics and Chemistry of Minerals, 2013
    Co-Authors: Valentina Lacivita, Roberto Orlando, Roberto Dovesi, Philippe D’arco, Alessio Meyer

    Abstract:

    The static linear optical properties (refractive indices, birefringence and axial angle) of Andradite–grossular (Ca3Fe2Si3O12–Ca3Al2Si3O12) solid solutions have been computed at the ab initio quantum-mechanical level through the Coupled Perturbed Kohn–Sham scheme, using an all-electron Gaussian-type basis set. Geometry relaxation after substitution of 1–8 Al for Fe atoms in the primitive cell of Andradite yields 23 non-equivalent configurations ranging from cubic to triclinic symmetry. Refractive indices vary quite regularly between the Andradite (1.860) and grossular (1.671) end-members; the birefringence δ and the axial angle 2V at intermediate compositions can be as large as 0.02° and 89°, respectively. Comparison with experiments suffers from inhomogeneities and impurities of natural samples; however, semi-quantitative agreement is observed.