The South Australian Government has identified water as a critical resource and a limiting factor in the development of magnetite resources in the Braemar Corridor of South Australia. A key recommendation in the Governments' “Magnetite Strategy” was for the determination of priority areas for future groundwater exploration and mapping to support the development.
A study of existing regional and finer-scale geophysical, particularly airborne electromagnetic (AEM) data, that cover the Braemar Corridor, was initiated to help better define the groundwater resource potential of the region. Historical AEM data sets (fixed-wing and heliborne) were combined, inverted, and a 3D conductivity model generated to enhance the understanding of aquifer systems present in the area, their spatial continuity and character (including groundwater quality). A critical output from this work was the definition of a product defined as a "Regolith-Sediment Aquifer Thickness" map, which defined the distribution of palaeovalley systems and the importance of fault/fracture systems along the NNW margin of the Murray Basin in generating thicker sequences of saturated sediments. These systems were then assessed for their potential against an extensive drillhole/stratigraphic data base developed through mineral exploration activities in the Braemar Corridor.
Their analysis coupled with those from existing hydrogeological investigations, determined that “higher yielding” bores away from sedimentary basin cover sequences to the south and north of the Corridor intersect groundwater in fractures/faults/bedding planes in Neoproterozoic rocks. Yields were often “airlift yields” with only local limited supply. The palaeovalleys defined on southern margins of Corridor were thin, only partially saturated and of limited value for groundwater supply. The best options for a more sustainable groundwater supply near existing magnetite resources were along fault systems, including the Anabama Fault, or in the northwards extension of palaeovalleys in the Eyre Basin on the north side of the Olary Spur. Recent groundwater investigations support this.