A Brief Description
Induced polarization (I.P.) was developed as a method of detecting metallic sulfides in base-metal prospecting . It has been used successfully for deep exploration in many countries worldwide. The system employs a direct current power source, which when pulsed, creates ionic halos at the surface of metallic particles. Upon interruption of the induced current, these ionic halos create a decaying voltage which may be detected at the surface. The resulting data may be plotted in several ways including; pseudo-sections, plan contours, horizontal profiles, or as depth soundings.
A series of current and potential electrodes are placed along a pre-determined line at specific intervals depending on the depth of penetration required. Increased penetration is achieved by expanding electrode separations; sometimes as wide as several thousand feet. Large current sources can provide depth penetrations in excess of 2000 feet (600 meters).
I.P. may be used for vein tracing where metallic sulfides are present as well as for the detection of large low-grade base-metal ore bodies, and also where precious metal are associated with other metallics. Induced polarization is incapable of locating oxide ore bodies where no sulfides are present. These types of ore bodies usually occur above the water table. For these applications resistivity or electromagnetic techniques are more applicable.
I.P. has also been proven effective in association with resistivity data for the detection of subterranean aquifers.