Mechanism and kinetics of element and isotopic exchange mediated by a fluid phase
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Ralf Dohmen
Abstract
We consider the fluid-mediated exchange of elements or isotopes between two mineral grains that are physically separated from each other in an analytical model. The process is found to depend on three non-dimensional parameters defined herein as β, γ, and δ. The behavior of a given system depends on only two of these (γ and δ), while the third (β) determines the rate. This allows us to define a reaction mechanism map as a function of γ and δ. These parameters can be calculated from independently measured or estimated thermodynamic, kinetic, and transport properties, thereby enabling a prediction of reaction mechanisms for the first time. It is found that at least six different reaction mechanisms are possible rather than just diffusion or interface control. Some of the more significant observations are that: (1) time scales of equilibration may be substantially greater than the diffusive time scale (x2/D); (2) rim compositions of zoned minerals may be out of equilibrium with each other and even with the adjacent fluid in some cases; and (3) solubility of the species of interest in the intergranular fluid plays a very important role in determining reaction behavior. We discuss case studies, selected from the literature, of garnet-biotite geothermometry and speedometry from granulite-facies metamorphic rocks in the light of the model to show that intergranular transport may be inefficient (rather than slow) in some cases. Finally, we consider the implications of these results for geothermometry, geospeedometry, and geochronometry
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
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- TEM investigation of forsterite dendrites
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- Chromian spinel during melting experiments of dry peridotite (KLB-1) at 1.0–2.5 GPa
- Resonant XPS study of the pyrite valence band with implications for molecular orbital contributions
- Petrology and mineralogy of wollastonite- and melilite-bearing paralavas from the Central Apennines, Italy
- Variation of antiphase domain size in omphacite: A tool to determine the temperature–time history of eclogites revisited
- Compressional and shear wave velocities of ringwoodite γ-Mg2SiO4 to 12 GPa
- A vibrational spectroscopic study of the oxidation of pyrite by ferric iron
- The atomic arrangement of the ganophyllite-group modulated layer silicates as determined from the orthorhombic dimorph of tamaite, with the elusive 16.8 Å ganophyllite-group superstructure revealed
- The crystal structure of chromian kassite from the Saranovskoye deposit, Northern Urals, Russia
- Spectroscopic and related evidence on the coloring and constitution of New Zealand jade
- Chemical speciation of Ag in galena by EPR spectroscopy
- Pressure dependence of melt viscosity in the system NaAlSi3O8-CaMgSi2O6
- Molecules in the SiO2-clathrate melanophlogite: A single-crystal Raman study
- Mn-rich tourmaline from Austria: structure, chemistry, optical spectra, and relations to synthetic solid solutions
- Compositional heterogeneity of olivine in thermally metamorphosed serpentinite from Southwest Japan
- Magnetic monitoring of hydrothermal magnetite nucleation-and-growth: Record of magnetic reversals
- High-temperature limits on viscosity of non-Arrhenian silicate melts
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Articles in the same Issue
- Melting of garnet peridotite: Effects of capsules and thermocouples, and implications for the high-pressure mantle solidus
- High-resolution and energy-filtered TEM of the interface between hematite and ilmenite exsolution lamellae: Relevance to the origin of lamellar magnetism
- The structural evolution of mercury sulfide precipitate: an XAS and XRD study
- Synthetic fluid inclusions as recorders of microfracture healing and overgrowth formation rates
- Fluid-induced nucleation of (Y+REE)-phosphate minerals within apatite: Nature and experiment. Part II. Fluorapatite
- A technique for measuring 3D crystal-size distributions of prismatic microlites in obsidian
- TEM investigation of forsterite dendrites
- Mechanism and kinetics of element and isotopic exchange mediated by a fluid phase
- Chromian spinel during melting experiments of dry peridotite (KLB-1) at 1.0–2.5 GPa
- Resonant XPS study of the pyrite valence band with implications for molecular orbital contributions
- Petrology and mineralogy of wollastonite- and melilite-bearing paralavas from the Central Apennines, Italy
- Variation of antiphase domain size in omphacite: A tool to determine the temperature–time history of eclogites revisited
- Compressional and shear wave velocities of ringwoodite γ-Mg2SiO4 to 12 GPa
- A vibrational spectroscopic study of the oxidation of pyrite by ferric iron
- The atomic arrangement of the ganophyllite-group modulated layer silicates as determined from the orthorhombic dimorph of tamaite, with the elusive 16.8 Å ganophyllite-group superstructure revealed
- The crystal structure of chromian kassite from the Saranovskoye deposit, Northern Urals, Russia
- Spectroscopic and related evidence on the coloring and constitution of New Zealand jade
- Chemical speciation of Ag in galena by EPR spectroscopy
- Pressure dependence of melt viscosity in the system NaAlSi3O8-CaMgSi2O6
- Molecules in the SiO2-clathrate melanophlogite: A single-crystal Raman study
- Mn-rich tourmaline from Austria: structure, chemistry, optical spectra, and relations to synthetic solid solutions
- Compositional heterogeneity of olivine in thermally metamorphosed serpentinite from Southwest Japan
- Magnetic monitoring of hydrothermal magnetite nucleation-and-growth: Record of magnetic reversals
- High-temperature limits on viscosity of non-Arrhenian silicate melts
- First reported sedimentary occurrence of berlinite (AlPO4) in phosphate-bearing sediments from Cioclovina Cave, Romania
