Low‐frequency electrical properties

Abstract

In the interpretation of induced polarization data, it is commonly assumed that metallic mineral polarization dominantly or solely causes the observed response. However, at low frequencies, there is a variety of active chemical processes which involve the movement or transfer of electrical charge. Measurements of electrical properties at low frequencies (such as induced polarization) observe such movement of charge and thus monitor many geochemical processes at a distance. Examples in which this has been done include oxidation‐reduction of metallic minerals such as sulfides, cation exchange on clays, and a variety of clay‐organic reactions relevant to problems in toxic waste disposal and petroleum exploration. By using both the frequency dependence and nonlinear character of the complex resistivity spectrum, these reactions may be distinguished from each other and from barren or reactionless materials.

Electrical properties of a graphite-rich quartzite from a former lower continental crust exposed in the Serre San Bruno, Calabria (southern Italy)

“…To measure these properties on cylindrical rock samples (height about 22 mm, diameter about 25 mm), a 2-pole and a 4-pole cell were used, constructed on ideas of Olhoeft (1979), Vinegar and (4-pole-cell) and high frequency data (2-pole-cell), solid platinum electrodes with a diameter of 26 mm were used as current electrodes in the cell, while a platinum net was used to measure the voltage drop across the sample (for details, see Markfort and Jödicke, 1998;Jödicke et al, 2004).…”

Integrated Geophysical Detection of DNAPL Source Zones

“…If the real and imaginary parts of the complex resistivity as a function of frequency are not related to each other by the Hubert Transform, then the discrepancy may be used to characterize another, independent characterization of nonlinearity called Hilbert Distortion (HD). Further discussion and details may be found in Olhoeft (1979a,b;1985). Measurement of the THD and HD are the discriminating elements in Nonlinear Complex Resistivity (NLCR) in addition to the resistivity magnitude and phase from linear complex resistivity.…”

“…However, the details of the waveforms may be used to derive considerable detail about the chemical reactions (resulting in an electrochemical analytical chemistry technique called cyclic voltammetry). The causes of the Hubert Distortion nonlinearity are not understood, but are related to the cation exchange process in clay and zeolite minerals (Olhoeft, 1979b;1985;Jonscher, 1986). There is no circuit analogue for the Hubert Distortion.…”

“…Laboratory measurements of the samples acquired for all of the sites described in this report were performed with equipment and procedures as described in Olhoeft (1979aOlhoeft ( , 1980 and using the fourth generation hardware and software as described in Jones (1997). In brief, the samples were placed in teflon sample holders {Olhoeft, 1980) with four bright platinum #52 mesh electrodes sandwiched between the three teflon sample sections.…”

“…give the Hubert Distortion nonlinear indicator {Olhoeft, 1979b;1985). The system measured an opened and a shorted sample holder to determine and remove the inductive and capacitative coupling between the wires connecting the measurement system to the sample holder and to remove the input impedance of the system.…”