Extracting IP Information from AEM Data to Improve the Hydrogeological Interpretation

Abstract

IP measurements in airborne EM data have not been previously considered for mapping groundwater distribution. IP modelling can be applied to discriminate between co-existing salty aquifers (conductive and non-chargeable) and extensive clay layers (conductive and chargeable); typical in both coastal areas and regions affected by dry-land salinity. The current case study presents the field results from a gold and metal project that had a hydrogeological mapping component to it in central Western Australia. Accounting for IP signal in the forward response was necessary to fit the data in localised areas, which were then interpreted as clay filled (conductive and chargeable) palaeochannels. The synthetic experiments that followed confirm that in favourable conditions, clay derived IP signal can affect the measured AEM response. Conversely, IP information can be recovered from these data, providing an extra physical parameter of value to the hydrogeological interpretation.