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CORRECTIONS FOR CONDUCTIVITY ESTIMATES IN INDUCTION PROSPECTING OF SULPHIDE DYKES IN A LAYERED ENVIRONMENT *
Author(s) -
NEGI J.G.,
GUPTA O.P.,
JOSHI M.S.
Publication year - 1987
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/j.1365-2478.1987.tb00846.x
Subject(s) - conductor , geology , conductivity , electrical conductor , conductance , resistive touchscreen , planar , mineralization (soil science) , mineralogy , electrical resistivity and conductivity , prospecting , anomaly (physics) , petrology , geophysics , geochemistry , soil science , condensed matter physics , materials science , composite material , chemistry , physics , computer graphics (images) , quantum mechanics , computer science , electrical engineering , engineering , soil water
In a weathered environment estimates of depth and conductance of metallic sulphide dykes from conventional anomaly index diagrams for a vertical half‐plane in air have to be corrected, besides the usual corrections, for: 1. moderate conductivity of the host rocks, and 2. finiteness of strike length S and depth extent D. Model experiments have been carried out to evaluate the response variation of a vertical planar conductor with varying depth extent and strike length for both insulating and conductive surroundings. The results indicate: 1. A conductor with finite depth extent ( D/L < 2.5) or strike length (S/L < 5.0) in an insulating medium yields a lower estimate of conductance (mineralization) and a greater depth. 2. A moderately‐conductive host rock enhances the anomaly and rotates the phase so that the conductor appears to be more resistive (less mineralized) and shallower. The results have practical significance since in weathered surroundings a highly‐mineralized body of finite size could be missed, or misjudged, because of low estimates of conductivity and depth.