An evaluation of spontaneous mineralization potentials

Abstract

There have recently been substantial developments in the theory and application of the self-potential (SP) technique as it applies to sulphide and other conductive mineralization. The present discussion evaluates the significance of these for the execution and interpretation of SP surveys. Recent developments include new numerical techniques for modelling the SP phenomenon that incorporate more realistic double-layer sources and take into account the conductivity distribution of the earth. These suggest two main applications for SP surveys. One application concerns the definition of the electrochemically induced double-layer source over the boundary of a mineralized region with known geometry and electrical characteristics. The other more conventional application requires the assumption of the source distribution, and so allows the determination of the electrical and geometrical parameters of the source body. Recent ideas on the variation of the electrochemical environment within the earth suggest that the mechanism for the generation of mineral self-potentials may not necessarily require the intersection of the source body and the water table. In this case the possibility exists that deep sulphide bodies lying completely below the water table may generate substantial spontaneous potentials. This provides an interesting opportunity for the SP technique in deeply weathered tropical terrains, where both conductive and resistive overburdens can combine to make the application of techniques employing artificial fields problematical.