Thermodynamic properties of the Tschermak solid solution in Fe-chlorite: Application to natural examples and possible role of oxidation
-
Olivier Vidal
,
Teddy Parra
Abstract
The standard-state thermodynamic properties of 14 Å Fe-amesite [Fe4Al4Si2O10(OH)8] were calculated from the reequilibration experiments of Pana et al. (2005) and natural data bearing on the Fe-Mg partitioning between chlorite and chloritoid over a wide range of pressure (P). temperature (7), and rock composition. The combination of these data with the three-site mixing model and thermodynamic properties of daphnite proposed by Vidal et al. (2001) led us to reappraise the evolution of the Margules parameter WGAlFe with pressure and temperature. The new data [H0fFe-Am = -7607460 J/mol, .S0Fe-Am = 514.8 J/(mol·K), V0Fe-Am = 20.90 J/bar, WGAlFe = 1200 - 31T + 0.7(P - 1)] are compatible with all the natural data and reequilibration experiments, and in fair agreement with the results of synthesis. They are used to calculate the compositional evolution of chlorite with T. P, or αO2 at different bulk-system compositions. The calculated phase relations and chlorite compositions are compared with previous experiments conducted in the FeO-Al2O3-SiO2-H2O system. The addition of the Fe-amesite end-member increases the number of equilibria that can be calculated for any natural assemblage involving chlorite. Two independent equilibria are obtained for natural (Fe-Mg)-chlorite-quartz or diaspore assemblages. It is therefore possible to estimate metamorphic conditions for high-variance assemblages from the composition of chlorite. We discuss the reliability of such P-T estimates using natural chlorites occurring in low-pressure and low-temperature or medium- to high-pressure and temperature samples. Assuming that the proposed model and thermodynamic parameters are correct, these various natural data suggest that XFe3+ [= Fe3+/(Fe2+ + Fe3+)] in metamorphic chlorites is low (<0.1), whereas it can be as high as 0.3 in Si- and Mg-rich chlorites formed at low -P-T conditions.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Comparative planetary mineralogy: Valence state partitioning of Cr, Fe, Ti, and V among crystallographic sites in olivine, pyroxene, and spinel from planetary basalts
- The origin of orthopyroxene/biotite + plagioclase coronas from the Bolangir anorthosite complex (India), and implications for reconstructing P-T paths
- Dellaventuraite, NaNa2(MgMn23+Ti4+Li)Si8O22O2, a new anhydrous amphibole from the Kajlidongri Manganese Mine, Jhabua District, Madhya Pradesh, India
- Successive zoning of Al and H in hydrothermal vein quartz
- The Ti-saturation surface for low-to-medium pressure metapelitic biotites: Implications for geothermometry and Ti-substitution mechanisms
- Thermochemistry of hydrotalcite-like phases in the MgO-Al2O3-CO2-H2O system: A determination of enthalpy, entropy, and free energy
- Igneous thermometers and barometers based on plagioclase + liquid equilibria: Tests of some existing models and new calibrations
- Thermodynamic properties of the Tschermak solid solution in Fe-chlorite: Application to natural examples and possible role of oxidation
- Experimental data on the Tschermak substitution in Fe-chlorite
- Nanometer-sized, divalent-Mn, hydrous silicate domains in geothermal brine precipitates
- Geometric crystal chemical models for structural analysis of micas and their stacking polytypes
- Fundamental difference between synthetic powder and natural or synthetic single-crystal 1M micas: Geometric homo-octahedral vs. geometric meso-octahedral sheets
- The crystal structures of synthetic Fe2(SO4)3(H2O)5 and the type specimen of lausenite
- Experimental study of plagioclase rim growth around anorthite seed crystals in rhyodacitic melt
- Luminescence study of defects in synthetic as-grown and HPHT diamonds compared to natural diamonds
- Molar absorptivities of OH and H2O in rhyolitic glass at room temperature and at 400600 °C
- Ordering and elasticity associated with low-temperature phase transitions in lawsonite
- Formation of metastable cubic-perovskite in high-pressure phase transformation of Ca(Mg, Fe, Al)Si2O6
- Oxygen isotope heterogeneities and diffusion profile in composite metamorphic-magmatic garnets from the Pyrenees
- Unmixed spinel in chromitite from the Iwanai-dake peridotite complex, Hokkaido, Japan: A reaction between peridotite and highly oxidized magma in the mantle wedge
- Mn-bearing “oxy-rossmanite” with tetrahedrally coordinated Al and B from Austria: Structure, chemistry, and infrared and optical spectroscopic study
- Geochemical applications of the simple salt approximation to the lattice energies of complex materials
- Letter: A method for controlling alkali-metal oxide activities in one-atmosphere experiments and its application to measuring the relative activity coeficients of NaO0.5 in silicate melts
- Letter: Very low solubility of rutile in H2O at high pressure and temperature, and its implications for Ti mobility in subduction zones
- Letter: Microscopic strain in synthetic pyrope-grossular solid solutions determined by synchrotron X-ray powder diffraction at 5 K: The relationship to enthalpy of mixing behavior
- Letter: Ferrous hydroxy carbonate is a stable transformation product of biogenic magnetite
Articles in the same Issue
- Comparative planetary mineralogy: Valence state partitioning of Cr, Fe, Ti, and V among crystallographic sites in olivine, pyroxene, and spinel from planetary basalts
- The origin of orthopyroxene/biotite + plagioclase coronas from the Bolangir anorthosite complex (India), and implications for reconstructing P-T paths
- Dellaventuraite, NaNa2(MgMn23+Ti4+Li)Si8O22O2, a new anhydrous amphibole from the Kajlidongri Manganese Mine, Jhabua District, Madhya Pradesh, India
- Successive zoning of Al and H in hydrothermal vein quartz
- The Ti-saturation surface for low-to-medium pressure metapelitic biotites: Implications for geothermometry and Ti-substitution mechanisms
- Thermochemistry of hydrotalcite-like phases in the MgO-Al2O3-CO2-H2O system: A determination of enthalpy, entropy, and free energy
- Igneous thermometers and barometers based on plagioclase + liquid equilibria: Tests of some existing models and new calibrations
- Thermodynamic properties of the Tschermak solid solution in Fe-chlorite: Application to natural examples and possible role of oxidation
- Experimental data on the Tschermak substitution in Fe-chlorite
- Nanometer-sized, divalent-Mn, hydrous silicate domains in geothermal brine precipitates
- Geometric crystal chemical models for structural analysis of micas and their stacking polytypes
- Fundamental difference between synthetic powder and natural or synthetic single-crystal 1M micas: Geometric homo-octahedral vs. geometric meso-octahedral sheets
- The crystal structures of synthetic Fe2(SO4)3(H2O)5 and the type specimen of lausenite
- Experimental study of plagioclase rim growth around anorthite seed crystals in rhyodacitic melt
- Luminescence study of defects in synthetic as-grown and HPHT diamonds compared to natural diamonds
- Molar absorptivities of OH and H2O in rhyolitic glass at room temperature and at 400600 °C
- Ordering and elasticity associated with low-temperature phase transitions in lawsonite
- Formation of metastable cubic-perovskite in high-pressure phase transformation of Ca(Mg, Fe, Al)Si2O6
- Oxygen isotope heterogeneities and diffusion profile in composite metamorphic-magmatic garnets from the Pyrenees
- Unmixed spinel in chromitite from the Iwanai-dake peridotite complex, Hokkaido, Japan: A reaction between peridotite and highly oxidized magma in the mantle wedge
- Mn-bearing “oxy-rossmanite” with tetrahedrally coordinated Al and B from Austria: Structure, chemistry, and infrared and optical spectroscopic study
- Geochemical applications of the simple salt approximation to the lattice energies of complex materials
- Letter: A method for controlling alkali-metal oxide activities in one-atmosphere experiments and its application to measuring the relative activity coeficients of NaO0.5 in silicate melts
- Letter: Very low solubility of rutile in H2O at high pressure and temperature, and its implications for Ti mobility in subduction zones
- Letter: Microscopic strain in synthetic pyrope-grossular solid solutions determined by synchrotron X-ray powder diffraction at 5 K: The relationship to enthalpy of mixing behavior
- Letter: Ferrous hydroxy carbonate is a stable transformation product of biogenic magnetite
