Rich, attractive and extremely dense: A geophysical review of Australian IOCGs

Abstract

Most Iron Oxide Copper-Gold deposits were initially discovered through regional magnetic and gravity targeting, but there have been few published investigations of their geophysics as a deposit class. This study investigates the magnetic and gravity anomalies associated with several IOCGs and assesses their variability as a function of their physical characteristics. 3-D magnetic and gravity inversion and forward modelling are used to generate 3-D bodies, whose physical characteristics are then modified to assess the utility of magnetic and gravity data to IOCG exploration. The hypothesis that IOCGs form as fault and/or pipe bound hydrothermal breccias is consistent with their geophysical signatures. These modelling experiments highlight that gravity data is a more robust tool for IOCG exploration than magnetics, and that high resolution gravity data is critical to the identification of IOCG deposits in the Gawler and Mount Isa provinces.