The Stuart Shelf region is a stable platform of Carpentarian and older crystallisation basement which is overlain by flat-lying Adelaidean and Cambrian sediments. It extends eastward from the exposed crystalline Gawler Block area to the mobile "Torrens Hinge" zone. The Olympic Dam copper-uranium deposit occurs near the eastern margin of the region in a zone of high magnetic relief which covers much of the ANDAMOOKA 1:250,000 sheet. The deposit was discovered by reconnaissance drilling of coincident gravity and magnetic highs by Western Mining Corporation Ltd in 1975. The mineralisation occurs beneath approximately 350 m of Adelaidean sediments, and therefore is an excellent example of the type of concealed ore body which will become a more frequent exploration target in the next decade. Regional gravity and magnetic data in the area are widely spaced and variable in quality. Interpretation of the magnetic data indicates that the Olympic Dam deposit occurs in an upfaulted basement block, with fault movement controlled by north-east and north-west trending fractures. Quantitative modelling indicates that the interpreted fault located immediately north of the deposit may contribute directly to the magnetic anomaly observed at Olympic Dam. The north-west trend which is prominent in the regional magnetic data is attributed to dolerite dykes which are eroded feeders to the lower Adelaidean Beda Volcanics. Detailed aeromagnetic data from BILLA KALINA improve the resolution of these anomalies in an area where they are not as evident in the regional data. The north-westerly trend is also evident in the region of more intense magnetic relief which contains the Olympic Dam anomaly. Interpretation of the depth to pre-Adelaidean basement in the region is complicated by the presence of several stratigraphically separate magnetic sources. Anomalies due to the Adelaidean Beda Volcanics and associated dolerite dykes are imposed on basement and intra-basement sources. These are distinguished on the basis of anomaly form, orientation and interpreted susceptibility values, but clear distinctions cannot always be made. The proposed regional interpretation of depth to basement shows some correlation with gravity features, but density variations within basement are also evident. Gravity interpretation is also complicated by the unknown contribution of the Cambrian Andamooka Limestone.