The Effective Use of Forward Modelling and Petrophysical Analyses in the Application of Induced Polarisation Surveys to Explore for Disseminated Sulphide Systems in the Paterson Province, Western Australia

Abstract

The Citadel Project is a JV between Rio Tinto Exploration (RTX) and Antipa Minerals extending over 400 km2 in North West WA. The project is targeting disseminated and massive copper sulphide systems beneath 40 to 120 m of transported Permian cover overlain by intermittent Cenozoic sand dunes. Dipole-Dipole (DD) and Pole-Dipole (PD) Induced Polarisation survey configurations were chosen as a cost effective method to prioritise 16 target areas. Induced Polarisation (IP) survey traverses over the known gold-copper-silver±tungsten Calibre and Magnum deposits illustrated the effectiveness of the IP method for detecting mineralisation and led to a 127 line km D-D and P-D Induced Polarisation survey being undertaken during the 2016 field season. The IP surveys highlighted multiple chargeability anomalies along the Calibre structural corridor of which 8 were selected for drill testing. On completion of drilling, forward modelling of chargeability and resistivity data, combined with petrophysical analysis of selected core samples provided a platform for testing geological concepts. In addition, it allowed the correlation of the chargeability data with drilling results, and the validation of inversion modelling results. In 2017 a new IP survey to further delineate the Blue Steel target and evaluate the Calibre structural corridor was proposed. As part of the planning process, forward modelling, along with information from regional AEM surveys illustrated that a Gradient Array IP survey would be a cost effective solution for exploring the Calibre structural corridor