The Carrapateena deposit, hosted by the Carrapateena Breccia Complex (CBC), lies within the eastern margin of the Gawler Craton. The CBC is overlain by approximately 470m of Stuart Shelf sediments, consisting of Wilpena Group sediments overlying Umberatana Group sediments. Adelaidean sediments overlay the Archaean to Mesoproterozoic crystalline basement. The basement is comprised of metasediments, volcanics and granites that have not undergone any substantial deformation since 1450 Ma.
The Carrapateena deposit is an IOCG hydrothermal breccia system. An initial petrographic study of selected samples within the CBC reported that copper-gold-rare-earth-element mineralisation occurs in a hematite-quartz-sericite mineralised sequence, of partly conglomeratic sediments with clasts and fragments of granite, gneiss and vein quartz, also with probable dykes of altered dolerite and felsic.
Mineralisation is dominated by coarse-grained disseminated chalcopyrite with common occurrences of sulphidic vein-fill and blebs.
Mineralisation is interpreted to be controlled by structures with the significant zones occurring at the intersection of NNW - SSE trending structures and E - W trending structures. The hosting structures are interpreted to be obliterated by the subsequent hydrothermal brecciation.
The copper mineralisation consists of chalcopyrite and bornite with a discrete high grade bornite zone. Seventy-nine drill holes totalling approximately 78,000 metres have been completed on the main deposit, returning key intersections such as 905m @ 2.17% Cu, 0.9g/t Au, 11.5g/t Ag, 255ppm U, 38.8% Fe, 0.169% Ce and 0.104% La including 82m @ 4.78% Cu and 1.1g/t Au.