Modelling the Magnetic Induced Polarisation (MIP) Response from the Down-Hole Magnetometric Resistivity (DHMMR) Method

Abstract

The Down-Hole Magnetometric Resistivity (DHMMR) method, an extension to the surface Magnetometric Resistivity (MMR) method, is an effective technique used for the exploration of massive sulphide deposits. The method is based on the ``in-hole' measurement of low-amplitude, low-frequency magnetic fields associated with galvanic current flow through the earth. To date, the interpretation of DHMMR data has focused on modelling the amplitude component (which reflects changes in resistivity), neglecting the phase component (which reflects changes in induced polarization). This paper proposes to address the numerical interpretation of decoupled axial component phase data using DHMMR data acquired from the Flying Doctor prospect (near Broken Hill, New South Wales) as a case study. 3D electromagnetic modelling of polarisable tabular bodies in a layered, non-polarisable, half space has provided useful results. In addition to demonstrating a systematic decrease in the size of phase anomalies with increasing distance from the receiver, we have shown that the phase anomaly due to a polarisable body is also dependent on the body's position relative to the transmitter and receiver.