The effect of fluorine on reaction-rim growth dynamics in the ternary CaO-MgO-SiO2 system

Abstract Growth of reaction rims is mainly controlled by a change in physical parameters such as pressure and temperature, a change in the chemical composition of the system, and/or by the presence of volatiles. In particular, the effect of volatiles other than water on reaction-rim growth remains poorly understood. To accurately model metamorphic and metasomatic processes, a quantification of the efect of volatiles on reaction-rim growth dynamics is necessary but hitherto missing. In this study, reaction rims were experimentally grown in a series of piston-cylinder experiments in the ternary CaO-MgO-SiO2 system at 1000 °C and 1.5 GPa with 0–10 wt% F for 20 min. In the fluorine-free system, a rim sequence of wollastonite (Wo) | merwinite (Mer) | diopside (Di) | forsterite (Fo) | periclase (Per) formed, complying with the stable phase configuration at water-saturated conditions. As soon as 0.1 wt% F was introduced into the system, humite group minerals (HGMs) and monticellite (Mtc) appeared, resulting in the multilayer rim sequence Wo | Mer | Mtc | Fo + HGMs | Per. In experiments with fluorine concentrations ≥0.5 wt%, cuspidine (Csp) appears in the layer sequence and represents the major fluorine sink. Our data show that the addition of fluorine may stabilize the fluorine-bearing phases cuspidine and HGMs to higher temperatures, which is in agreement with previous studies (Grützner et al. 2017). However, the appearance of the nominally anhydrous minerals (NAMs) monticellite and åkermanite (Ak) at this P-T condition suggests that the addition of fluorine may also afect the stability of nominally fluorine-free minerals. This may be explained by the efect of fluorine on the Gibbs free energies of fluorine-bearing phases, which in turn afects the relative Gibbs free energies and thus the stabilities of all phases. An increase in absolute rim thickness from 11.8(21) to 105.6(22) μm (1σ standard deviations in parentheses) in fluorine free and 10 wt% F experiments, respectively, suggests that fluorine enhances absolute component mobilities and thus results in faster rim growth rates. Additionally, due to the presence of fluorine, a change in relative component mobilities results in microstructural changes such as a phase segregation of diopside and cuspidine at high-fluorine (≥3 wt% F) concentrations. These results not only imply that reaction rims may be used as a tool to infer the amount of fluorine present during metamorphic reactions but also that we need to consider the role of fluorine for a correct interpretation of the P-T-t history of metamorphic and metasomatic rocks.

• Publication year

  2022

• Venue

  Goldschmidt2021 abstracts

• Publication date

  2022-07-27

• Fields of study

  Not labeled

• Identifiers
  DOI 10.7185/gold2021.5189
• External record

  Open on Semantic Scholar

• Source metadata

  Semantic Scholar

• No claims are published for this paper.

• No concepts are published for this paper.

• Fluorine partitioning between humite-group minerals and aqueous fluids: implications for volatile storage in the upper mantle

  2019cited by this paper
• The effect of H2O fluid on relative component mobilities in a bimineralic reaction rim in the system CaO–MgO–SiO2

  2019influential reference
• Subduction factory in an ampoule: Experiments on sediment-peridotite interaction under temperature gradient conditions

  2018cited by this paper
• The role of F-clinohumite in volatile recycling processes in subduction zones

  2017cited by this paper
• Synthesis of monticellite–forsterite and merwinite–forsterite symplectites in the CaO–MgO–SiO2 model system: influence of temperature and water content on microstructure evolution

  2017cited by this paper
• Effect of water on the fluorine and chlorine partitioning behavior between olivine and silicate melt

  2017influential reference
• Experimental investigation of the kinetics of the spinel-to-garnet transformation in peridotite: A preliminary study

  2016cited by this paper
• An experimental study on the influence of fluorine and chlorine on phase relations in peralkaline phonolitic melts

  2014cited by this paper
• Growth kinetics of MgSiO3 perovskite reaction rim between stishovite and periclase up to 50 GPa and its implication for grain boundary diffusivity in the lower mantle

  2013cited by this paper
• Very little water is necessary to make a dry solid silicate system wet

  2013cited by this paper
• Thermodynamic model for growth of reaction rims with lamellar microstructure

  2012cited by this paper
• The effect of water on intergranular mass transport: new insights from diffusion-controlled reaction rims in the MgO–SiO2 system

  2012influential reference
• Experimental growth of diopside + merwinite reaction rims: The effect of water on microstructure development

  2012influential reference
• Experimental growth of åkermanite reaction rims between wollastonite and monticellite: evidence for volume diffusion control

  2011influential reference
• Growth of multilayered polycrystalline reaction rims in the MgO–SiO2 system, part II: modelling

  2011cited by this paper
• An improved and extended internally consistent thermodynamic dataset for phases of petrological interest, involving a new equation of state for solids

  2011influential reference
• Growth of multilayered polycrystalline reaction rims in the MgO–SiO2 system, part I: experiments

  2011cited by this paper
• Thermodynamic Model For Reaction Rim Growth: Interface Reaction and Diffusion Control

  2011cited by this paper
• Dependence of reaction kinetics on H2O activity as inferred from rates of intergranular diffusion of aluminium

  2010cited by this paper
• Reaction rim growth in the system MgO-Al2O3-SiO2 under uniaxial stress

  2010cited by this paper
• Enhancement of solid-state reaction rates by non-hydrostatic stress effects on polycrystalline diffusion kinetics

  2010cited by this paper
• Matrix rheology effects on reaction rim growth I: evidence from orthopyroxene rim growth experiments

  2009cited by this paper
• Growth kinetics of enstatite reaction rims studied on nano-scale, Part I: Methodology, microscopic observations and the role of water

  2007cited by this paper
• Grain boundaries as reservoirs of incompatible elements in the Earth's mantle

  2004cited by this paper
• Silicon and oxygen self diffusion in enstatite polycrystals: the Milke et al. (2001) rim growth experiments revisited

  2004influential reference
• Diffusion‐controlled growth of wollastonite rims between quartz and calcite: comparison between nature and experiment

  2002cited by this paper
• Phase relations of a serpentine composition between 5 and 14 GPa: significance of clinohumite and phase E as water carriers into the transition zone

  2001influential reference
• Grain boundary diffusion of Si, Mg, and O in enstatite reaction rims: a SIMS study using isotopically doped reactants

  2001cited by this paper
• Grain boundary diffusion in enstatite

  1997cited by this paper
• Rates of grain boundary diffusion through enstatite and forsterite reaction rims

  1997influential reference
• Water in the oceanic upper mantle: implications for rheology

  1996cited by this paper
• Grain boundary diffusion of oxygen, potassium and calcium in natural and hot-pressed feldspar aggregates

  1995cited by this paper
• An equation of state for carbon dioxide valid from zero to extreme pressures

  1994cited by this paper
• The effect of fluid chemistry on wetting textures in novaculite

  1991cited by this paper
• Grain-Boundary Diffusion Kinetics in Silicate and Oxide Minerals

  1991cited by this paper
• Kinetics of diffusion-controlled mineral growth in the Christmas Mountains (Texas) contact aureole

  1988cited by this paper
• Evolution of mineral assemblage zoning in diffusion metasomatism

  1977cited by this paper
• Interdiffusion studies in the system MgOAl2O3

  1969cited by this paper
• Epitaxial Growth of Spinel by Reaction in the Solid State

  1963cited by this paper

• No citing papers are available for this paper.