Application of 3D Cole-Cole inversion by Offset Pole-Dipole TimeDomain IP data for mineral exploration in South Australia

The TDIP method is one of the most useful methods for the mineral exploration, especially for identifying the presence or absence of sulfide minerals. However, it is difficult to explain whether the chargeable anomaly obtained by the conventional Time-Domain IP method is necessarily due to the sulfide minerals containing base metals. Therefore, recently, there is much research about the identification or classification of the chargeable minerals that are the source of the chargeability anomaly from the parameters of the Cole-Cole model. By analysing the different frequency characteristics of minerals, we can estimate whether the chargeability anomaly is caused by minerals containing the base metals. In this paper, we applied 3D Cole-Cole inversion using Time-Domain IP survey data conducted around the Menninnie Dam zinclead deposit in South Australia. Additionally, we selected Offset Pole-Dipole array as the electrode arrangement, which can reduce the effects of electromagnetic coupling. A 3D inversion program considering the Cole-Cole model was applied, which gave not only resistivity and chargeability but also the time constant. The inversion results were consistent with the results of existing IP surveys in the area and drilling and showed that the specialized offset configuration was effective. In addition, the Cole-Cole inversion showed that the time constant increased in proportion to the chargeability simply, and further study is required to estimate the distribution of the target mineralization.