The Electrical Conductivity of Polycrystalline Olivine and Pyroxene Under Pressure

Schock, R.N.; Duba, A.; Heard, H.C.; Stromberg, H. D.

doi:10.1016/b978-0-12-468750-9.50009-7

Cited by 44 publications

(25 citation statements)

References 19 publications

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“…The San Carlos olivine specimen studied by Duba and Nicholls (1973) had an edge dislocation density of 2-3 • l0 s/cm 2 , which is similar to that estimated for mantle olivine under 50 bars of shear stress by Kohlstedt et al, (1976). In addition, no significant enhancement was observed in olivine conductivity by Schock et al, (1977) in the girdle-anvil apparatus which produces nonhydrostatic stresses larger than that expected in the mantle. The presence of other phases can alter the transport properties of olivine through their influence on its point-defect chemistry (Stocker and Smyth, 1978).…”

Section: Laboratory Conductivity Measurements Crystalline Materialscontrasting

confidence: 46%

“…The presence of pyroxene will cause little alteration since its conductivity is about that of olivine . When measurements are made within the temperature-fo 2 range appropriate to maintain the stability of olivine crystals, conductivities generally fall within a range of one order of magnitude at a given temperature (Duba etal., 1974;Duba et al, 1976;Schock et al, 1977). This is observed to be true for single crystals and polycrystaUine material at pressures from one to 50 kilobars.…”

Section: Laboratory Conductivity Measurements Crystalline Materialsmentioning

confidence: 59%

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Relations of electrical conductivity to physical conditions within the asthenosphere

Waff

1980

Geophysical Surveys

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Abstract. This paper examines the constraint placed by electrical conductivity on physical conditions existing within the mantle. Determination of bulk electrical conducfivities of multiphase materials from knowledge of individual phase conductivities and their relative fractions is discussed in the light of recent studies of the equilibrium phase geometries of partial melts. It is concluded that existing models which are based on assumed geometries offer little refinement over Hashin-Shtfikman variational bounds. The possible effects of the gravitational field on phase geometry in partial melts and the resulting conductivity anisotropy are considered. At this time it appears that minimum melt fractions can be safely estimated from a knowledge of Earth conductivity combined with laboratory data on melt and crystalline conductivities and the Hashin-Shtfikman upper bound. The question of whether or not the asthenosphere corresponds to a zone of partial melting is also addressed.

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Section: Laboratory Conductivity Measurements Crystalline Materialscontrasting

confidence: 46%

Section: Laboratory Conductivity Measurements Crystalline Materialsmentioning

confidence: 59%

Relations of electrical conductivity to physical conditions within the asthenosphere

Waff

1980

Geophysical Surveys

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“…An interesting aspect of their study (that may be applicable to silicate Earth materials) is that the grain boundary effect could be nearly eliminated by using ultra-pure materials free of silica and minimized by utilizing high dopant concentrations and doping cations of large ionic radius. Grain boundaries are thought to be blocking to electronic conduction mechanisms (Schock et al 1977). Fo9o is thought to be an electronic conductor below 1390 ~ C and an ionic conductor at temperatures above 1390~ (Schock et al 1989).…”

Section: Discussionmentioning

confidence: 99%

“…It has been previously suggested that grain boundaries may be responsible for enhanced conduction in olivine-rich rock (e.g., Shankland and Waft 1977;Shankland 1981;Kariya and Shankland 1983). A study by Schock et al (1977) on the conductivity of ground-and-pressed polycrystalline olivine suggested that grain boundaries have only a small effect on the overall conductivity. The conductivity of a dunite fi'om Jackson County, North Carolina has been studied by Constable and Duba (1990).…”

Section: Introductionmentioning

confidence: 97%

Frequency dependent electrical properties of dunite as functions of temperature and oxygen fugacity

Roberts

Tyburczy

1993

Phys Chem Minerals

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Abstract. Using impedance spectroscopy, we have measured the electrical properties of two dunites and a single crystal olivine sample from 1000 to 1200 ~ C as a function of oxygen fugacity (Jo2)-Two conduction mechanisms with resistances that add in series are observed for the dunites corresponding to grain interior and grain boundary conduction mechanisms. The conductivities for each mechanism were determined by analyzing the data using a complex nonlinear least squares fitting routine and the equivalent circuit approach. The grain interiors display a conductivity dependent on Jo2 to the 1/5.5-1/7 power, consistent with other determinations, and interpreted as indicating small polaron transport (Fe'Mg). The grain boundaries demonstrate a weaker fo~ dependence that is dependent on temperature and material. Under certain conditions thefo~ dependence of the grain boundary conductivity is negative. This result indicates that oxygen ion transport is probably not the dominant grain boundary charge transport mechanism; however, an unequivocal determination of the grain boundary mechanism has not been achieved. In some dunites the grain boundaries are more conductive than the grain interiors; in other dunites they are more resistive than grain interiors. The grain boundaries do not enhance the total conductivity of any of the materials of this study but are the controlling mechanism in some instances. Measurement of the complex electrical response at frequencies as low as 10 -4 Hz is required to determine the role of grain boundaries on the overall electrical properties of polycrystalline dunite.

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“…This one simple question may be split up into several, possibly unanswerable, questions: What does the mantle material consist of, which partial pressures of oxygen and water do exist in the upper mantle, how can one control technically upper mantle conditions in a laboratory, how can one get mantle material, etc. In a recent paper Schock et aL (1977) solved the problem of the nature of the mantle material, or its main constituent at least, by referring to Shakespeare (1622). This up to now widely unknown petrologist, in his tragedy Othello, indeed mentioned 'chrysolite' as the material of which the Earth consists.…”

Section: Introductionmentioning

confidence: 97%

Relations between electrical conductivity and petrological parameters of the crust and upper mantle

Haak

1980

Geophysical Surveys

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Abstract. Laboratory data of the electrical conductivity of rocks and minerals pertinent to the deeper crust and upper mantle are summarized. They are discussed in the context of a theory to calculate effective conductivities of materials in the state of partial melt. Most published data have been obtained by too rapid measurements, i.e. without reaching an equilibrium state of the sample. Conductivity measurements on a material similar to the composition of pyrolite are not yet known, their importance is outlined. A global conductivity distribution obtained by electromagnetic induction studies is represented by a few results coveting oceanic and continental areas. Till today it seems to be a doubtful venture to deduce the temperature of the upper mantle or even the existence of a partial molten asthenosphere from a global conductivity distribution. On a more local scale the correlation of electrical conductivity with temperature and state of the material seems to be more realistic. This is tentatively shown by two petrological models of the Afar depression in Ethiopia and of the midoceanic rift.

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The Electrical Conductivity of Polycrystalline Olivine and Pyroxene Under Pressure

Cited by 44 publications

References 19 publications

Relations of electrical conductivity to physical conditions within the asthenosphere

Relations of electrical conductivity to physical conditions within the asthenosphere

Frequency dependent electrical properties of dunite as functions of temperature and oxygen fugacity

Relations between electrical conductivity and petrological parameters of the crust and upper mantle

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