Closing the gap between Airborne EM and Ground Galvanic Induced Polarization for Mineral Exploration

It is demonstrated and nowadays accepted that the Induced Polarization effects can affect inductive measurements and can be a source of artifacts if not proper modelled during inversion process. At the same time, using a dispersive resistivity to model EM data largely expands the model space and expose the inversion procedure to strong equivalencies and ambiguities. These limitations have often brought to over-precautionary modelling approaches of AIP and leaded to the impossibility in interpretation of the airborne-retrieved chargeability models. With this contribution a novel modelling approach to extract inductive induced polarization from Airborne EM data is proposed. The AEM data are acquired in Spain, for VMS and polymetallic exploration and overlap 17 ground DCIP lines. The modelling approach we propose concerns a re-parametrization of the Cole-Cole model to an equivalent less-correlated parametrization and a split of the spectral parameters during the inversion procedure. To prove the modelling, a comparison with the ground DCIP lines will be shown. This latter one has been modelled with the same parametrization and inversion scheme of the AEM data to provide a robust comparison between the two and reduce ambiguities in the interpretation. Then, to evaluate the AIP sensitivity to ground chargeable bodies, a joint inversion between the two entire datasets will follow and a vertical and lateral resolution-improved chargeability model is retrieved. This shows the AIP information content and contribute in the enhance of data sensitivity during the modelling procedure.