The application of SIROTEM in weathered terrain

Abstract

SIROTEM has been widely used over many different terrains in the past two years. Considerable success has been achieved in detecting mineral deposits (e.g. Elura and Teutonic Bore) occurring under conductive overburden up to 100 m thick. The best response of these deposits is in the time window of approximately 2.6 to 50 ms. The orebody response is obscured at delay times earlier than 2.6 ms. The response for 100 m loops at delay times greater than 50 ms is less than the noise level of 0.2 m V/A. To provide an interpretation base for SlROTEM data, a system has been set UP to model responses from thin dipping dykes, in air and in conductive media. A SIROTEM unit was used to collect the modelling data, with both separated and coincident loops configurations. Features of these modelling results relevant to the interpretation of responses obtained from field measurements are discussed in detail. The apparent resistivity output of SIROTEM provides a means for producing in-field pseudo-sections of apparent resistivity. The capability of SlROTEM to produce apparent resistivity values can be extended to large scale surveys for stratigraphic mapping. These results are interpreted with the aid of modelling results for layered media.