The late Palaeoproterozoic Wallaroo Group is interpreted to have been deposited during a major rift event in the south-eastern Gawler Craton during ~1770-1740 Ma. On Yorke Peninsula the group contains three lithological units, viz. Wandearah Formation (metasediments, five members), Weetulta Formation (felsic volcanics, three members) and Matta Formation (mafic volcanics, two members). The rocks have been metamorphosed, generally to a higher grade in the west (up to middle amphibolite facies), and become lower grade to the east (greenschist to sub-greenschist facies). Out of this group of rocks, the Aagot Member of the Wandearah Formation contains well-exposed outcrops, whereas all of the other units have been described mainly from subcrops. It is postulated that the original deposition of the Wallaroo Group into a Palaeoproterozoic sedimentary basin might have had a westerly situated, late Archaean - early Palaeoproterozoic provenance and a general eastwards-deepening depositional regime, with shallow-water arenaceous and arkosic deposits being laid down in the south and south-west and relatively deep-water, laminated argillites, carbonates and chemical sediments forming in the east and north-east. The presently remaining metasediments are intercalated with mafic and felsic volcanics, which locally exhibit hyaloclastic deposits at their contact margins. Sedimentation is interpreted to have been terminated by a major compression event during ~1730-1710 Ma (= Kimban Deformation 3). Observed bi-modality of volcanism in the Wallaroo Group suggests that there may have once existed the potential to form sedimentary-exhalative or volcanic-hosted massive sulphide deposits, but any that were so formed would probably have later been remobilised during subsequent deformations to form low-grade Cu, or minor Pb and Zn deposits, in which the minerals are re-distributed along foliation or fold axial planes and compositional layers. The Wallaroo Group was intruded by early Mesoproterozoic Tickera Granite (1598-1586 Ma), Arthurton Granite (1582 Ma) and Curramulka Gabbronorite (1583 Ma) on Yorke Peninsula. These granites and gabbronorite were deformed at least twice prior to the Neoproterozoic. The processes of granite intrusion, deformation and associated alteration are considered to be responsible for the Moonta and Wallaroo mineralisation. Early magmatic crystallisation of ore metal-rich minerals, coupled with late exsolution of the magmatic volatile phase, may possibly have been promoted by the relatively deeper emplacement of the cumulatic gabbronorite. Magmatic fluids were probably generated by ascending A-type, miarolitic granites during this event, and the fluids forced into fault zones and dilatant fractures. Contemporaneous deformation appears to have progressed as a two-stage event. The first stage involved northeast-southwest compression and reverse faulting, which created north-west (300-340 degrees) trending, plus east-west trending, brittle ductile shear zones (parallel to the Wallaroo mine lodes): this was accompanied by the creation of north-east trending en echelon tension gash arrays (parallel to the Moonta mine lodes). The subsequent second deformation stage involved conjugate shearing, and probably occurred during the cooling stage of magma intrusions; the associated shearing and faulting has displaced the Cu-Au lodes. Updated TEISA aeromagnetic data show complex structures existing across Yorke and Eyre Peninsulas, the interpretation of which will provide valuable insights into the tectonic history of the south-eastern Gawler Craton. Three pre-Neoproterozoic deformation events (at ~1730-1710, ~1580 and ~1500 Ma) are recognised in the Moonta-Wallaroo area, and the known mineralisation emplacement is interpreted to have been associated with D2 non-coaxial faulting and haematite-chlorite ± kaolinite alteration. The inferred widespread occurrence of similar early Mesoproterozoic magmatism in the eastern Gawler Craton therefore makes the whole of this region highly prospective for mineral exploration.