TEM Surveys

tem-surveyAlpha Geoscience have successfully delineated ore bodies using  TEM in Australia. The Transient Electromagnetic (TEM) or Time-Domain Electromagnetic (TDEM) technique utilizes differences in the electrical properties of geologic materials to map subsurface conditions. An electric current is induced into the ground by a loop of wire laid out on the ground surface. These induced currents propagate downward into the subsurface and are increasingly influenced by the electrical properties of deeper layers. A series of measurements of the secondary magnetic field are used to model electrical resistivity as a function of depth. Changes in subsurface resistivity values can result from changes in lithology, water content, pore-water chemistry, and the presence of electrically conductive ore minerals.