Influence of oxygen fugacity on the electrical conductivity of hydrous olivine: Implications for the mechanism of conduction

Dai, Lidong; Karato, Shun‐ichiro

doi:10.1016/j.pepi.2014.04.003

Cited by 36 publications

(60 citation statements)

References 16 publications

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“…A series of simple‐shear experiments within the P–T conditions of the blueschist facies was conducted, and the resulting fabrics were measured by microscopic observations, EBSD measurements, and TEM analyses. Usually, the main factors that influenced the development of microfabrics are temperature, strain rate, confining pressure, and oxygen fugacity [e.g., Stipp et al , ; Dai and Karato , ]. We consider temperature, strain rate, and confining pressure as variables in this study and consider their influence on the experimentally derived microstructures.…”

Section: Discussionmentioning

confidence: 58%

Deformation microstructures of glaucophane and lawsonite in experimentally deformed blueschists: Implications for intermediate‐depth intraplate earthquakes

et al. 2015

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A series of simple-shear experiments on blueschist was performed at 400-500°C and 1-2.5 GPa to understand the deformation of seismically active, subducting oceanic crust. The experiments show that brittle microstructures are mainly found at pressures of 1-2 GPa, whereas ductile microstructures form at 2.5 GPa. J-indices (a measure of fabric intensity) of glaucophane crystal preferred orientations change systematically with changing shear strain and confining pressure, and the angle between the slip plane and the shear direction of samples deformed at >2 GPa is similar to that of a strain ellipsoid. These results, together with the variable orientations of fine grains in a selected area electron diffraction image at 2 GPa, indicate that the brittle-ductile transition for glaucophane occurs at~2 GPa. In contrast to this, lawsonite in the experiments show abundant fracturing in most specimens and a poor correlation between the J-index, shear strain, and confining pressure. This demonstrates that lawsonite deformed by brittle failure under all experimental conditions. In the case of a starting material that has a strong fabric and deformed under dry experimental conditions, the brittle-ductile transition zone of glaucophane will be much shallower than 2 GPa. Therefore, our initial experimental results on the deformation behavior of blueschist indirectly support the dehydration embrittlement of subducting oceanic crust (glaucophane) as an important factor in the origin of intraplate earthquakes.

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Section: Discussionmentioning

confidence: 58%

Deformation microstructures of glaucophane and lawsonite in experimentally deformed blueschists: Implications for intermediate‐depth intraplate earthquakes

et al. 2015

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“…There have been debates on how water (hydrogen) enhances electrical conductivity in minerals (e.g., (Karato and Wang, 2013;Yoshino and Katsura, 2013)). This issue on olivine has been discussed in detail based on our new results on the pressure effect (Dai and Karato, 2014a), the oxygen fugacity effect (Dai and Karato, 2014c), and the temperature effects (Dai and Karato, 2014b;Karato, 2013b). Therefore we will not repeat these discussions here.…”

Section: A Comparison To Previous Studiesmentioning

confidence: 99%

“…For instance, there are some suggestions for low oxygen fugacity, fO 2, in the lunar interior although deep interior might have higher fO 2 (e.g., (Wieczorek et al, 2006)). The influence of fO 2 on hydrogen-related conduction in olivine was determined by Dai and Karato (2014c) and therefore the influence of fO 2 can be corrected if fO 2 in these planets were known. However the magnitude of correction is not very large (a change in fO 2 by three orders of magnitude will change the electrical conductivity by a factor of $2) compared to the uncertainties in other factors (e.g., temperature, inferred magnitude of conductivity).…”

Section: Potential Applications To Planetary Interiorsmentioning

confidence: 99%

Influence of FeO and H on the electrical conductivity of olivine

Dai

Karato

2014

Physics of the Earth and Planetary Interiors

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“…[]. Other experimental measurements have completed the data set [ Yoshino et al ., ; Poe et al ., ; Yang , ; Dai and Karato , ] but the laws derived from these studies predict contrasted conductivities [ Wang et al ., ; Yoshino et al ., ; Poe et al ., ; Jones et al ., ], precluding any unequivocal interpretation of electrical conductivities in the upper mantle in terms of mantle hydration (Figure a). Much of the debate has focused on the incompatibility of the laws of Wang et al .…”

Section: Introductionmentioning

confidence: 99%

Toward a unified hydrous olivine electrical conductivity law

Gardès

Gaillard

Tarits

2014

Geochem Geophys Geosyst

123

185

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It has long been proposed that water incorporation in olivine has dramatic effects on the upper mantle properties, affecting large-scale geodynamics, and triggering high electrical conductivity. But the laboratory-based laws of olivine electrical conductivity predict contrasting effects of water, precluding the interpretation of geophysical data in term of mantle hydration. We review the experimental measurements of hydrous olivine conductivity and conclude that most of data are consistent when errors in samples water contents are considered. We report a new law calibrated on the largest database of measurements on hydrous olivine oriented single crystals and polycrystals. It fits most of measurements within uncertainties, and is compatible with most of geophysical data within petrological constraints on mantle olivine hydration. The conductivity anisotropy of hydrous olivine might be higher than dry olivine, but preferential orientation should produce moderate anisotropy ($0-0.8 log unit). In the oceanic mantle, the enhancement of olivine conductivity is limited to $1 log unit in the maximum range of mantle olivine water concentrations (0-500 wt ppm). Strongest enhancements are expected in colder regions, like cratonic lithospheres and subduction settings. High conductivities in melt-free mantle require great depths and high water concentrations in olivine (>0.1 S/m at >250 km and >200 wt ppm). Thus, the hydration of olivine appears unlikely to produce the highest conductivities of the upper mantle.

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Influence of oxygen fugacity on the electrical conductivity of hydrous olivine: Implications for the mechanism of conduction

Cited by 36 publications

References 16 publications

Deformation microstructures of glaucophane and lawsonite in experimentally deformed blueschists: Implications for intermediate‐depth intraplate earthquakes

Deformation microstructures of glaucophane and lawsonite in experimentally deformed blueschists: Implications for intermediate‐depth intraplate earthquakes

Influence of FeO and H on the electrical conductivity of olivine

Toward a unified hydrous olivine electrical conductivity law

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