A review of AEM data in South Australia

Abstract

Subsurface resistivity is a key component of many mineralization models including unconformity-related uranium, palaeochannel hosted uranium and nickel sulphide exploration. It is also a key component in understanding environmental aspects of the subsurface including groundwater detection, and civil engineering applications including detection of buried pipes and cables. Measuring subsurface resistivity is the aim of electromagnetic (EM) geophysical techniques. It involves transmitting an electromagnetic field into the Earth, and then recording this field - and the Earth response - on a receiver. The transmitted field signal can be removed from the received field to determine the Earth response. Airborne EM (AEM) is a geophysical technique that allows this process to be undertaken from an airborne (aeroplane or helicopter) platform. AEM exploration first commenced in South Australia with AFMAG (Audio-Frequency Magnetic technique) surveys in the 1960s, and VLF (Very Low Frequency) surveys from 1971. Numerous platforms including RepTEM, GeoTEM, Input, QUESTEM, HoistEM, TEMPEST and VTEM are now routinely used within South Australia. Each technique provides a different view of the subsurface dependant on the system parameters and the processing undertaken on the data. Given the increase in AEM surveying within South Australia and the wide applications available for this data a review of this technique within the State has been undertaken. This poster presents a summary of AEM within South Australia, focussing on a number of significant surveys and their outcomes. Surveys in the Cariewerloo Basin and Fowler Domain in particular have been used to model uranium prospectivity and help define nickel deposits. All data reviewed is now downloadable online via SARIG.