Conductivity Spectra of Rocks From the Craigmont Ore Environment

Fraser, Dean; Keevil, N. B.; Ward, S. H.

doi:10.1190/1.1439425

Cited by 27 publications

(11 citation statements)

References 2 publications

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“…The total current density across a hand specimen has been experimentally found to be a linear function of the electric field for small values of current density [Fraser et al, 1963]. A phase shift between the current and the electric field has been reported by every experimenter.…”

Section: Xh = Aoh]• + J'--i•0dmentioning

confidence: 91%

“…above 100 Hz. Fraser et al [1963], making laboratory measurements with mineralized rocks at frequencies between 0.1 Hz and 1if' Hz, observed deviation of less than 4% from a linear relationship when current densities below 10-' amps/cm • were used. The site of the phenomenon of polarization in rocks, i.e., the metal-electrolyte interface and/or the clay-electrolyte interface, implies the existence of space-charge inhomogeneities and physical-chemical potentials, the first causing gradients of the electric field and the second constituting local sources of electromotive force.…”

Section: A New Attempt To Describe Electromagnetically a Polarizable mentioning

confidence: 98%

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Analytical model for a polarizable medium at radio and lower frequencies

Dias¹

1972

J. Geophys. Res.

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The Maxwell equations are written and discussed in the frequency domain for a medium exhibiting electrical polarization at radio and lower frequencies, in the range of linearity between current density and electric‐field intensity. A complex function of frequency is proposed for the conductivity, which is able to describe all the families of available experimental curves for rock samples in the natural state, showing the effect of polarization. Such a function is a constitutive relation for the polarizable medium in the frequency domain. The concept of ‘abnormal’ dielectric constant for rocks is discussed in the context of the physical mechanisms responsible for the effect of electrical polarization at radio frequencies and below. Such a concept, always possible theoretically, only introduces confusion in the understanding of the basic physical mechanisms involved. As an alternative the extensive use of the concept of a total current complex conductivity is suggested.

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Section: Xh = Aoh]• + J'--i•0dmentioning

confidence: 91%

Section: A New Attempt To Describe Electromagnetically a Polarizable mentioning

confidence: 98%

Analytical model for a polarizable medium at radio and lower frequencies

Dias¹

1972

J. Geophys. Res.

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“…The real part, given by (o" + we"), is responsible for the in-phase component of the observed current, whereas the imaginary part, given by (a" +we'), is responsible for the quadrature component (Fraser et al 1964;Dias 1968Dias , 1972Fuller & Ward 1970). Many models have been proposed to describe the electrical behaviour of rocks, each of which attempted to explain a particular feature in some restricted frequency interval.…”

Section: Y=~gmentioning

confidence: 99%

Fractal Geometry, porosity and complex resistivity: from rough pore interfaces to hand specimens

Rocha

Habashy

1997

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We propose a new model to interpret the electrical behavior of rocks containing metallic or clay particles. This new model encompasses some of the other commonly used models as special cases.This model is a generalization of two models, one developed by Dias (Journal of Geophysical Research 77, 4945-4956, 1972) and another by Pelton et at. (Geophysics 43, 589-609, 1978). Its circuit analog includes an impedance K(iw,) -'~ which simulates the effects of the fractal rough pore interfaces between the conductive grains (metallic or clay minerals which are blocking the pore paths) and the electrolyte. This generalized Warburg impedance is in series with the resistance of the blocking grains and both are shunted by the double layer capacitance. This combination is in series with the resistance of the electrolyte in the blocked pore passages. The unblocked pore paths are represented by a resistance which corresponds to the normal DC resistivity of the rock. The parallel combination of this resistance with the 'bulk' sample capacitance is finally connected in parallel to the rest of the above-mentioned circuit. The model was tested over a wide range of frequencies against experimental data obtained for amplitude and phase of resistivity or conductivity as well as for the complex dielectric constant. The samples studied are those of sedimentary, metamorphic and igneous rocks.

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“…The influence of the pore water chemical composition on induced polarization of clayey media was investigated, for instance, by Vacquier et al (1957), Fraser et al (1964), Klein and Sill (1982), Vinegar and Waxman (1984), and Revil et al (2013aRevil et al ( , 2013b. They show that the chargeability (a ratio of polarization to conduction) decreases when the salinity increases because conduction currents of the bulk pore water increase with salinity.…”

Section: Introductionmentioning

confidence: 99%

Spectral induced polarization of clay-sand mixtures: Experiments and modeling

et al. 2014

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International audienceSpectral induced polarization or complex conductivity is a promising electric method in hydrogeophysics because of its sensitivity to water saturation, permeability, and particle size distribution (PSD). However, the physical and chemical mechanisms that generate the low-frequency complex conductivity of clays are still debated. To explain these mechanisms, the complex conductivity of kaolinite, smectite, and clay-sand mixtures was measured in the frequency range 1.4 mHz-12 kHz with various clay contents (100%, 20%, 5%, and 1% in volume of the clay-sand mixture) and salinities (distilled water, 0.1 g L-1, 1 g L-1, and 10 g L-1 of NaCl in solution). The results indicated the strong impact of the cation exchange capacity of smectite upon the complex conductivity of the material. The quadrature conductivity increased steadily with the clay content and was fairly independent of the pore fluid salinity. A mechanistic induced polarization model was also developed. It combined a Donnan equilibrium model of the surface electrochemical properties of clays and sand, a conduction model of the Stern and diffuse layers, a polarization model of the Stern layer, and a macroscopic conductivity model based on the differential effective medium theory. It also included the effect of the PSD. Our complex conductivity model predicted very well the experimental data, except for very low frequencies (<0.1 Hz) at which membrane polarization may dominate the observed respons

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Conductivity Spectra of Rocks From the Craigmont Ore Environment

Cited by 27 publications

References 2 publications

Analytical model for a polarizable medium at radio and lower frequencies

Analytical model for a polarizable medium at radio and lower frequencies

Fractal Geometry, porosity and complex resistivity: from rough pore interfaces to hand specimens

Spectral induced polarization of clay-sand mixtures: Experiments and modeling

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