Chemically induced grain boundary migration in calcite: temperature dependence, phenomenology, and possible applications to geologic systems

Hay, Randall S.; Evans, Brian

doi:10.1007/bf00375220

Cited by 43 publications

(16 citation statements)

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“…Chemically induced grain boundary migration is one possible phenomenon. This phenomenon has been observed to generate an undulatory interface (Hay and Evans, 1987), and can explain the undulatory profile in the diopside. One of proposed mechanisms of chemically induced grain boundary migration is that a thin layer (nanometers thickness) ofliquid wetting the grain boundary drives dissolutionlreprecipitation to move the grain boundary (Evans et aI., 1986;Handwerker, 1988).…”

Section: Mass Transport Mechanisms Other Than Lattice Diffusionmentioning

confidence: 83%

Kinetic processes of mantle minerals

Koga¹

1999

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This dissertation discusses the experimental results designed to constrain the processes of MORE generation. The main focus of this study is to investigate the location and the related processes of the transformation boundary from spinel to garnet peridotite facies at subsolidus conditions, because the presence of garnet in melting residues has significant influence to the conclusion drawn from geochemical/geophysical observations. Using an approach that monitors the rate of reaction progresses, the experimental results confirmed the presence of a region that garnet and spinel coexist in peridotite compositions. The trace element distribution among the product phases (opx and cpx) subsequent to the garnet breakdown reaction is in disequilibrium, due to the differences of diffusivity between major and trace elements. The presence of disequilibrium distribution in nature may be used to infer time scales of geodynamic processes. Diffusion coefficients of Al in diopside are experimentally determined, and used for modeling the equilibration of major elements in pyroxene during MORE genesis. In summary, this dissertation contributes two major inferences: the location of the transformation boundaries of the gamet-spinel peridotite; the presence of disequilibrium trace elements distribution with equilibrium major elements distribution in mantle pyroxenes.3

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Section: Mass Transport Mechanisms Other Than Lattice Diffusionmentioning

confidence: 83%

Kinetic processes of mantle minerals

Koga¹

1999

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“…The driving force for GBM can increase with increasing chemical disequilibrium [ Stünitz , 1998]. Grain boundary migration activated by compositional gradients has previously been described by Hay and Evans [1987] and defined as CIGM (chemically induced grain boundary migration). In most cases there will be a combination of SIGM (structurally induced grain boundary migration) and CIGM as deformation often occurs over a range of PT conditions which changes the chemical equilibrium in the minerals leading to an additional chemical driving force [ Stünitz , 1998].…”

Section: Discussionmentioning

confidence: 99%

Linking temperature estimates and microstructures in deformed polymineralic mantle rocks

Linckens

Herwegh

Müntener

2011

Geochem. Geophys. Geosyst.

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[1] To constrain deformation temperatures of mantle shear zones, we studied a strike-slip shear zone (Hilti massif, Semail ophiolite, Oman) and focused on the interaction between microstructural mechanisms and chemical equilibration processes. Quantitative microfabric analysis on harzburgites with different deformation intensity (porphyroclastic tectonite, mylonite, and ultramylonite) was combined with orthopyroxene geothermometry. The average grain size of all phases decreases with decreasing shear zone thickness. Dynamic recrystallization of porphyroclasts in combination with dissolution-precipitation and nucleation result in small-sized, chemically equilibrated pyroxenes. The composition of orthopyroxene was used to calculate deformation temperatures. In the case of the porphyroclastic tectonites, the chemical composition of orthopyroxene has been reset by diffusion yielding temperature estimates of 880-900°C. The mylonites were deformed by dislocation creep of olivine and show a broad range of calculated temperatures, which result from a combination of grain size reduction and inheritance of equilibrium compositions from earlier high-temperature events and diffusion. In mylonites, diffusion profiles combined with geothermometry and grain size analysis indicate a mylonitic deformation temperature of 800-900°C possibly followed by diffusion. In ultramylonites, the smallest grains (<30 mm) reveal equilibration at temperatures of ∼700°C during the last stages of ductile deformation, which was dominated by diffusion creep of olivine. Our results provide a crucial link between temperature and evolution of microstructures from dislocation creep to diffusion creep in mantle shear zones.

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“…Experimental studies have shown that grain boundary migration (strictly speaking interphase boundary migration) can take place due to disequilibrium between an infiltrating fluid and the solid phases (Hay and Evans 1987). The process is termed chemically induced grain boundary migration (CIGBM).…”

Section: Comparison With Experimental Flow Lawsmentioning

confidence: 99%

Plastic flow of omphacite in eclogites at temperatures below 500°C – implications for interplate coupling in subduction zones

Piepenbreier

Stöckhert

2001

Int J Earth Sci

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In subduction zones oceanic crust of the downgoing plate presumably forms a continuous interlayer between the upper and the lower plate. During subduction, the basaltic material is transformed to eclogite. Thus, the flow strength of eclogite must pose an upper bound to shear stresses across the plate boundary for the deeper levels of subduction zones. Up to now, experimental flow laws for wet diopside have been applied to predict the strength of eclogites. However, based on experimental calibration the material would be essentially undeformable by dislocation creep at 650 C. Even at 700 C a strain rate of 10 ±14 s ±1 would still imply a differential stress of ca. 150 MPa. Omphacite microstructures in eclogites from the Piemonte Zone, Western Alps, reveal shape-preferred orientation, subgrains and sutured high-angle grain boundaries due to migration recrystallization, and a pronounced crystallographic preferred orientation. These textures indicate that the omphacite was deformed by dislocation creep. In contrast, garnet forms rigid inclusions within the weaker pyroxene matrix. Fe±Mg exchange thermometry for garnet omphacite pairs indicates temperatures of 46550 C (Valle di Locana) and 47550 C (Vallone di Saint Marcel), for a pressure of 1.5 GPa. These results are not consistent with the predictions based on experimental flow laws for diopside. Our data suggest that the flow strength of sodic pyroxene is significantly lower than that of diopside. This finding is consistent with the homologous temperature concept, with the melting temperature of jadeite at 3 GPa being approximately 350 C lower than that of diopside. In addition, dynamic migration recrystallization of omphacite in the investigated samples can be linked to small chemical changes. This indicates that mobile grain boundaries formed an effective pathway for the exchange of ions and that this exchange was fast compared to the rate of boundary migration. Thus, the combined reduction of stored strain energy and chemical free energy provided the driving force for recrystallization. The potential effects of these chemical changes on flow strength remain to be explored.

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Chemically induced grain boundary migration in calcite: temperature dependence, phenomenology, and possible applications to geologic systems

Cited by 43 publications

References 73 publications

Kinetic processes of mantle minerals

Kinetic processes of mantle minerals

Linking temperature estimates and microstructures in deformed polymineralic mantle rocks

Plastic flow of omphacite in eclogites at temperatures below 500°C – implications for interplate coupling in subduction zones

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