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Technique: The two most common resistivity methods are direct current and electromagnetics. Direct current
resistivity measurements require electrode placements at the surface through which current is applied and voltage measurements are taken. When direct current resistivity measurements are taken, induced polarization techniques can also be employed. This procedure allows better definition of some features, as the two methods are complimentary. Data presented by resistivity methods can then be mapped to indicated size and depth of a target.
(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. Technique: A series of current and potential electrodes are placed along a pre-determined line at specific intervals depending on the depth of penetration required.
Mr. Hewitt has over 40 years of experience working with mining companies in the same type of business as the Company, as a consultant, conducting testing and advising on sites for drilling in both oil, water and minerals, and in the manufacture of engineering and manufacture geophysical equipment used in the mining industry, both in the United States and abroad. Mr. Hewitt is the President of Geo-Western, a geophysical testing company and was also a partner in Hewitt Enterprises, Inc. in the business of contracting services and instrument manufacturing for use in the mining industries.
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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 sub-terranean aquifers.
Many detection systems use electromagnetic waves to measure a variety of responses. Their frequencies-range covers a broad span of the electromagnetic spectrum. Equipment employing E.M. techniques range from satellite imagery to metal detectors and instruments which measure ground conductivity. Very-low to ultra-low frequency instruments are normally used in ground penetrating applications to achieve maximum depth. Time domain EM, sometimes referred to as PULSE EM which employs a self contained transmitter-receiver circuit, is used for detection of metallic objects either in water or underground at great depths depending on transmitted power, receiver sensitivity and coil arrangement.
EM Mining Inc., completed the Geo-physical testing of 28 unpatented claims and came back with outstanding results which includes an inferred assay finding of 3 major ore bodies and 1 source of shallow water. One of the ore bodies contains high grade copper (12%) PT which starts at the surface. We secured rock samples there and sent a sample to Reno for analysis. 12% P/T high copper, 40 oz silver P/T, and .06 oz of gold P/T. The first 1000’ contains 54 mil. tons. The other two larger sulfide zones will require core samples to confirm the depth, quality and value of what appears to be precious metals.
Geophysicist Garry Hewitt.
EM instrumentation is available for satellite deployment, aircraft platforms, shipboard and ground use as well as submarine applications. Technique: EM systems are used effectively in mapping geologic formations and buried mineral deposits. Underwater detection of metallic targets, buried metal objects, archeological features, and subsurface caverns are common applications. EM methods are also effective in locating metal accumulations in placer deposits.
Measures changes in ground conductivity due to variations in ground-water, salt content, and porosity of the medium. This phenomenon makes resistivity exploration very effective in mapping sub-surface, oxidized mineral deposits and geological formations. It is also very effective in fault tracing, cavern mapping, and ground-water investigation. Resistivity applications are also highly effective in mapping archaeological sites. Recently, resistivity techniques have been used to map ground permeation of industrial chemicals.