Airborne Electromagnetic Methods as Applied to the Sear~h for Sulphide Deposits

CIM Bulletin, 1971

N. R. PATERSON, Consulting Geophysicist, Norman R. Paterson and Associates, Toronto, Ontario

More than a dozen AEM systems are currently being used in the routine exploration for massive sulphides. The systems differ from one another in minor respects, but fall into four main categories: rigid-coupled in-phase/quadrature systems; towed-bird, s ingle-component systems; differential systems; and passive systems. Although field tests are important in demonstrating the performance characteristics of the AEM/airframe assembly (noise-levels, coupling effects, etc.), more meaningful evaluations can be made through physical or computer modelling. The latter approach has been used to compare the response of twelve AEM systems to both vertical and horizontal sheets, simulating a large orebody and a conductive overburden respectively. The effects of height changes are also studied. The results demonstrate that each AEM system has its own particular advantages and disadvantages. The relative importance of these is a matter for the geophysicist to judge, on the basis of specific geological and environmental information. Data currently available on AEM systems are adequate to permit an objective evaluation of the systems for a particular exploration program.
Keywords: bird, conductor, overburden, quadrature, University of Toronto, Conductivity, Data, Geophysics, Noise, Performance, sulphide, Sulphides, Survey, Surveys, Systems