Geoelectrics

Is the amount of pore space the most important factor controlling electrical conductivity?

The main difference between resistivity-resistance and conductivity-conductance is that the former is related to the material and is a physical property of it (intensive property: does not depend on the system size or the amount of material in the system)

Mostly, the conduction nature in rocks is mainly electronic (Metallic conduction and/or Electronic semi-conductors)

The main difference between Metallic Conduction and Electronic Semiconductors is that the latter needs a much more significant amount of energy (heat) for the electrons to become dissociated from their home atoms

Fluid conductivity depends also upon temperature because the mobility of the ions in solution decreases with temperature.

Metallic conductors resistivity depends on temperature. When the temperature increases the conductivity of the metal decreases.

The electronic semi-conductors are metallic materials just as native metals, the only difference is that they have a smaller number of free electrons with lower mobility.

It is possible to obtain movement of ions within a solid due to imperfections

The tortuosity is defined by the relation between the average length of the path through the crack and the length of the rock lc/l

The diminution ratio is the division between the cross-section area of the crack and the cross-section total area

When the current flows more easily in some direction than in others is called Anisotropy

The longitudinal resistivity is always greater than the transverse resistivity.

The anisotropy coefficient SQRT(RT/RL) >= 1

The main difference between IP and SP is that the former is mainly used to determine massive ore bodies whereas the latter is mainly used to determine disseminated ore bodies

The SP potentials tend to increase in positiveness with the direction of water flows as the electric charge flows in the opposite direction.

The advantage of using a fixed spacing SP survey is that you can use a shorter wire and the reduced importance of telluric currents (generally long-wavelength currents induced in the ground by geomagnetic fluctuations).

The major advantage of using a fixed spacing SP survey is that generally needs to operators to moves the system

The gridded measurements in the SP fixed spacing survey should ultimately form a closed loop and the sum of all potentials within that loop should equal zero if not the remainder represents an error and should not be distributed among the readings

The main disadvantage of using a fixed electrode system (sp) is that system include generally more measurement errors and that is not easy to perform by a single operator

The main advantage of using a fixed electrode system is that the larger separation between electrodes does not allow telluric currents to influence the results

SP can be easily executed on Ice.

the observed current and potential due to a single source in a half space is identical to that from the method of images inspired model of two sources in an infinite space.

Is the method of the ratio and the method of the Vmin give the true position of the ore body

When the profile is drawn the
reference (zero) potential needs to be set as the value for which the potential becomes constant far from the
body, this process is helped by a good lateral extent of measurements and a low level of noise.