Structural interpretation of the pre-Adelaidean basement from aeromagnetic and gravity data defines uplifted basement blocks and basement fractures which were active as normal faults during deposition of Adelaidean sediments, controlling the deposition of sedimentary units and playing major part in localizing base metal deposits. The copper and associated metals originated either in the basement or at the base of the Adelaidean succession, perhaps in the Roopena Volcanics. They were leached by hot connate brines and transported along fault and fracture channelways into the near surface environment. Deposition of metal sulphides took place wherever Eh-pH conditions and the availability of sulphur allowed, either in marine or groundwater regime, but always close to the structurally controlled channelways.