Natural field induced polarization for mapping of deep mineral deposits: A field example from Arizona

Abstract

A field example of the natural field induced polarization (NFIP) method over a known deep induced polarization (IP) target in Arizona corroborates NFIP's excellent potential as a commercial survey technique for the mineral industry. Data processing and interpretation were successful in extracting the response of the IP target from the natural field signals in the presence of a conductive surface layer. The location of the interpreted IP target correlated well with interpretations from an earlier IP/resistivity dipole-dipole survey. The imaginary component of the ratio of electric field measured along the profile normalized by the electric field at a reference site becomes nonzero over the position of an IP target. The complex ratio of the profiling dipole electric field and fixed-reference-dipole electric field, plotted as a function of frequency and dipole location, is a simple and robust procedure for recovering the IP effect. The NFIP method eliminates the expense and energy requirements of deploying large transmitters and is sensitive to deeper structures (structures that are difficult to resolve using traditional methods). Thus, this method is a valuable mapping tool for identification of IP targets.