Reaction kinetics of dolomite rim growth

Helpa, Vanessa; Rybacki, E.; Abart, Rainer; Morales, Luiz F. G.; Rhede, Dieter; Jeřábek, Petr; Dresen, Georg

doi:10.1007/s00410-014-1001-y

Cited by 11 publications

(15 citation statements)

References 33 publications

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“…Dolomite rims consist of palisade-shaped, elongated grains growing into magnesite and granular dolomite grains growing toward calcite reactants. In addition, large magnesio-calcite grains formed in contact with granular dolomite due to the incorporation of Mg into pure calcite, which is interpreted as a precursor to dolomite nucleation (Helpa et al 2014). Grain sizes of magnesiocalcite tend to increase from the dolomite boundary toward pure calcite (Fig.…”

Section: Reaction Rim Microstructuresmentioning

confidence: 97%

“…In a previous study (Helpa et al 2014), we investigated diffusion-controlled dolomite reaction rim growth at the contacts of oriented calcite and magnesite single crystals at isostatic conditions of pressure P = 400 MPa, T = 750-850 °C and t = 3-146 h. Polycrystalline dolomite reaction rims showed a palisade-like microstructure in contact with magnesite and granular grains in contact with calcite. In between the granular dolomite and the calcite reactant, large magnesio-calcite grains evolved due to the incorporation of magnesium into the calcite reactant.…”

Section: De Ronde and Stünitzmentioning

confidence: 98%

“…3b-d, g) evolved in static annealing experiments using comparable starting materials and similar P, T, t conditions ( Fig. 3a; adopted from Helpa et al 2014). The boundary between palisades and granular dolomite was identified by platinum markers as the initial contact of starting materials.…”

Section: Reaction Rim Microstructuresmentioning

confidence: 99%

“…A combination of electron backscatter diffraction (EBSD, TSL DigiView) and semiquantitative energy-dispersive spectroscopy (EDS) was used for investigations, which allowed unambiguous identification of the phases. Details of operating conditions and evaluating procedures are described by Helpa et al (2014). Transmission electron microscopy (TEM) examinations were done using a Tecnai™G2 F20 X-twin microscope equipped with a field emission gun (FEG).…”

Section: Analytical Techniquesmentioning

confidence: 99%

See 3 more Smart Citations

Influence of stress and strain on dolomite rim growth: a comparative study

Helpa

Rybacki

Morales

et al. 2015

Contrib Mineral Petrol

Self Cite

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Section: Reaction Rim Microstructuresmentioning

confidence: 97%

Section: De Ronde and Stünitzmentioning

confidence: 98%

Section: Reaction Rim Microstructuresmentioning

confidence: 99%

Section: Analytical Techniquesmentioning

confidence: 99%

See 2 more Smart Citations

Influence of stress and strain on dolomite rim growth: a comparative study

Helpa

Rybacki

Morales

et al. 2015

Contrib Mineral Petrol

Self Cite

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“…These models have been substantiated by a vast body of rigorous experimental work constraining the kinetics of reaction rim growth (e.g. Farver and Yund, 1996;Yund, 1997;Fisler et al, 1997;Milke et al, 2001;Watson and Price, 2002;Milke and Heinrich, 2002;Milke and Wirth, 2003;Abart and Schmidt, 2004;Schmid et al, 2009;Götze et al, 2010;Keller et al, 2008;Niedermeier et al, 2009;Dohmen and Milke, 2010;Keller et al, 2010;Joachim et al, 2011a, b;Mueller et al, 2012;Helpa et al, 2014Helpa et al, , 2015Jonas et al, 2015;Abart et al, 2016). Phenomenological models of disequilibrium elemental and isotopic compositions produced experimentally with incomplete diffusive element exchange (e.g.…”

Section: Reaction Kineticsmentioning

confidence: 99%

Arrested development – a comparative analysis of multilayer corona textures in high-grade metamorphic rocks

Ogilvie

Gibson

2017

Solid Earth

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Abstract. Coronas, including symplectites, provide vital clues to the presence of arrested reaction and preservation of partial equilibrium in metamorphic and igneous rocks. Compositional zonation across such coronas is common, indicating the persistence of chemical potential gradients and incomplete equilibration. Major controls on corona mineralogy include prevailing pressure (P ), temperature (T ) and water activity (aH 2 O) during formation, reaction duration (t) single-stage or sequential corona layer growth; reactant bulk compositions (X) and the extent of metasomatic exchange with the surrounding rock; relative diffusion rates for major components; and/or contemporaneous deformation and strain. High-variance local equilibria in a corona and disequilibrium across the corona as a whole preclude the application of conventional thermobarometry when determining P -T conditions of corona formation, and zonation in phase composition across a corona should not be interpreted as a record of discrete P -T conditions during successive layer growth along the P -T path. Rather, the local equilibria between mineral pairs in corona layers more likely reflect compositional partitioning of the corona domain during steadystate growth at constant P and T .Corona formation in pelitic and mafic rocks requires relatively dry, residual bulk rock compositions. Since most melt is lost along the high-T prograde to peak segment of the P -T path, only a small fraction of melt is generally retained in the residual post-peak assemblage. Reduced melt volumes with cooling limit length scales of diffusion to the extent that diffusion-controlled corona growth occurs. On the prograde path, the low melt (or melt-absent) volumes required for diffusion-controlled corona growth are only commonly realized in mafic igneous rocks, owing to their intrinsic anhydrous bulk composition, and in dry, residual pelitic compositions that have lost melt in an earlier metamorphic event.Experimental work characterizing rate-limiting reaction mechanisms and their petrogenetic signatures in increasingly complex, higher-variance systems has facilitated the refinement of chemical fractionation and partial equilibration diffusion models necessary to more fully understand corona development. Through the application of quantitative physical diffusion models of coronas coupled with phase equilibria modelling utilizing calculated chemical potential gradients, it is possible to model the evolution of a corona through P -T -X-t space by continuous, steady-state and/or sequential, episodic reaction mechanisms. Most coronas in granulites form through a combination of these endmember reaction mechanisms, each characterized by distinct textural and chemical potential signatures with very different petrogenetic implications. An understanding of the inherent petrogenetic limitations of a reaction mechanism model is critical if an appropriate interpretation of P -T evolution is to be inferred from a corona. Since corona modelling employing calculated chemical potential gradie...

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Derivation of Kinetics and Design Parameters for a Carbonator Reactor in a Greenhouse Calcium Looping Process

et al. 2017

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The carbonation/calcination reaction cycle of a limestone sorbent was studied experimentally by using a thermogravimetric analyzer for unique conditions, such as low temperature (400 to 500 °C) and low CO2 partial pressure (0.05 to 0.1 %), pertinent to a novel greenhouse calcium looping process. The kinetic parameters were obtained and compared with those reported in the literature. Various gas–solid reaction mechanisms were considered to determine the best reaction mechanism for the carbonation reaction. The diffusion function, or G(x)=x2, had the best least‐squares linear fit, which resulted in a first‐order reaction for the carbonation reaction in the greenhouse calcium looping process. Moreover, the activation energy and pre‐exponential factor of the carbonation reaction were established to be 19.7 kJ mol−1 and 295.8 min−1 kPa−1, respectively. The derived kinetic parameters were used in Aspen Plus to optimize the carbonator reactor size. The required size of the reactor decreased with increasing operating temperature of the reactor. Exergy analysis revealed that the overall exergetic efficiency of greenhouse calcium looping could be more than 80 %.

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Reaction kinetics of dolomite rim growth

Cited by 11 publications

References 33 publications

Influence of stress and strain on dolomite rim growth: a comparative study

Influence of stress and strain on dolomite rim growth: a comparative study

Arrested development – a comparative analysis of multilayer corona textures in high-grade metamorphic rocks

Derivation of Kinetics and Design Parameters for a Carbonator Reactor in a Greenhouse Calcium Looping Process

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