Integration of magnetotelluric and deep seismic data to map crustal architecture in the Mt Isa region, Northern Australia Implications for Mineral Prospectivity

Mount Isa Province in northern Australia is one of the world's most strongly endowed regions for base metals and host to major iron-oxide-copper-gold (IOCG) deposits. The Carpentaria Conductivity Anomaly at the eastern margin of the Province is a major electrical conductivity structure of the Australian continent. We have used magnetotelluric and deep seismic reflection data to image the crustal architecture in this complex region to understand the crustal-scale fluid pathways and potential mineral occurrences. The resistivity models reveal a number of prominent crustal-scale conductors, suggesting that the Carpentaria Conductivity Anomaly is likely caused by a series of isolated or interconnected bodies. These conductors characterise the position and geometry of the ancient Gidyea Suture Zone, interpreted as a west-dipping subduction zone. The conductivity anomaly may record the activity of fluid hydration involved during a subduction event, with the enhanced conductivity likely being caused by deformation or mineralisation of graphitic or sulfidic rocks during orogensis. The distribution of known gold and copper deposits shows a close spatial correlation with the suture zone, suggesting that this structure is potentially a fundamental control on IOCG deposits in its vicinity. The interpretation of the seismic image shows a good correlation with the resistivity models. The implication is that crustal-penetrating structures act as potential pathways for fluid movement to form mineral deposits in the upper crust. The significance of mapping such structures using geophysics is highlighted for mineral exploration.

This Abstract was submitted/presented to the 2022 Sub 22 Conference 28-30 November (http://sub22.w.tas.currinda.com/)