Crustal architecture during the early Mesoproterozoic Hiltaba-related mineralisation event: are the Gawler Range Volcanics a foreland basin fill?

The tectonic setting of Hiltaba Suite (1595‚-1575 Ma) magmatism within the Gawler Craton has long been regarded as anorogenic, accompanied by mild extension (Flint et al. 1993; Creaser 1995). This evaluation was largely based on the apparently limited deformation recorded within the Hiltaba Suite and Gawler Range Volcanics, their enriched geochemical signature and the high-temperature nature of magmatism. However, there is now growing evidence that contractional fault reactivation, metamorphism and locally pervasive deformation were associated with the emplacement of the Hiltaba Suite and the associated iron oxide ‚- copper‚-gold (IOCG) ¬± uranium and gold mineral systems, suggesting the existence of a compressional regime in the early Mesoproterozoic Gawler Craton. In this contribution, we briefly summarise evidence for crustal-scale early Mesoproterozoic deformation in the Gawler Craton and suggest it forms part of a broader system that incorporates the Olarian Orogeny of the Curnamona Province. In the light of the new data on the spatial nature of early Mesoproterozoic deformation and metamorphism across southern Australian Proterozoic terranes (Fig. 1), we suggest that the Gawler Range and Benagerie volcanics are an unusual volcanic-fill within a foreland basin that formed within a broadly NW‚-SEdirected compressional regime.