A coherent and related system of Mesoproterozoic magmatism, hydrothermal alteration and deformation extends from the western Gawler Craton to eastern Curnamona Province. This system produced the Olympic Dam iron oxide – copper–gold (IOCG) orebody and the Olympic Cu–Au Province metallogenic system in addition to gold-dominant deposits of the Central Gawler Gold Province and related prospects across the Gawler Craton and Curnamona Province. Such an extensive system requires the input of an enormous amount of energy, and energy on such a scale can only be delivered into the crust from the mantle. Therefore, understanding the composition and evolution of the mantle lithosphere beneath the Gawler Craton is a key component towards understanding the evolution of the Mesoproterozoic mineral systems in this region. We have recently published a major new geochemical and isotopic dataset that focuses on the mafic rocks of the Gawler Craton. This dataset includes 132 surface and drill core samples. Each sample was analysed for whole-rock major and trace element geochemistry and selected samples were also analysed for Sm–Nd isotopic composition. In this paper we describe the major patterns evident in the new dataset in relation to a subset of samples associated with IOCG and gold mineral deposits and prospects. We also discuss the implications of the recognition of compositional heterogeneity and evidence for metasomatism in the source regions for the Mesoproterozoic mafic rocks of the Gawler Craton. We conclude that the IOCG and related mineral systems were fundamentally influenced by the mantle composition in terms of both its ability to melt and the magmas and metals thus released during this melting event.