The application of the mise-a-la-masse electrical technique in Greenstone belt gold exploration

Abstract

Most of the gold deposits in the Barberton Greenstone belt of South Africa are relatively small and in structurally complex geological areas.The mise-a-la-masse electrical technique, where a current electrode is earthed in a mineralised zone, was used on one of our exploration projects consisting of a sulphides/gold-bearing carbonaceous banded iron formation within a succession of mafic, ultramafic and sedimentary rocks. The technique was successful in delineating individual mineralised units within a broad lithological sequence. During the survey, electrical potential measurements were recorded on surface, in underground drives and in twenty five boreholes. Measurements were also repeated by earthing the mineralised zone in a number of boreholes. Major discontinuities were recognised within the ore zones and used to interpret geological structures. These were then used to define specific units for ore reserve calculations and the application of selected mining techniques.

Materials provided at the workshop Geophysical map interpretation on the PC, convened April 21-22, 1993

“…This also demonstrates the capabilities of the programs ID, UTILITY, and GHIST, which report on the grid specifications, manipulate aspects of the grid structure and values, and look at the data distribution, respectively. These examples constitute part of the independent exercises presented later in this chapter (p. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. A full description of the files used below are found in Chapter 12.…”

“…The available options and descriptions for their use are as follows: -,789,123': This rather cryptic information refers to the <keypad+>, <keypad->, <Home>, <Up arrow>, <PgUp>, <End>, <Down arrow>, and <PgDn> keys which correspond to the <+>, <->, <7>, <8>, <9>, <1>, <2>, and <3> keys on the numeric keypad available on many keyboards. The <Home>, <Up arrow>, and [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Imvis <PgUp> keys respectively increase the intensity of the red, green, and blue in the color palette. The <End>, <Dovn arrow>, and <PgDn> keys decrease the red, green, and blue intensities, respectively.…”

“…NOTE: The histogram option does not work on an unzoomed image. If you [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Imvis are interested in looking at histograms of areas of the entire image, first execute the zoom option using a box which is larger than the image.…”