Exploration for possible buried Olympic Dam style Cu-Au-U-REE deposits in Proterozoic basement on the eastern flanks of the Peake and Denison Ranges, in an area located approximately 65 km south-east of Oodnadatta, has concentrated on a very large Bouguer gravity anomaly (the Toby prospect) lying proximal to the north-eastern margin of the Gawler Craton and to the Torrens Hinge Zone. Work completed to date has consisted of doing regional prospectivity studies, image interpretation and geophysical modelling of available aeromagnetic and gravity data (which has resolved a number of arcuate basement features suggestive of calderas or volcanogenic collapse structures similar to those inferred for the Stuart Shelf and Katinka prospect areas), and the drilling of a 261 m deep rotary precollar hole for a planned deep test of the Toby prospect. A 3 m bottomhole core was cut from bedrock in the drillhole, which was later petrographically identified as being an altered massive microdolerite, partly brecciated and with extensive carbonate and smectite alteration. Secondary iron oxide stains and trace small grains of native copper were observed in the drill core sample thin sections, but assays of the rock proved unremarkable. Licence operator Platsearch then decided not to deepen the hole to the target depth of 600 m by diamond drilling, since the required indications of proximity to an Olympic Dam - type mineralising environment appeared to be absent, and on 8/4/2004 Platsearch transferred its 50% licence interest back to the other licensees. During the remaining licence period the incumbents have sought to attract a new joint venture partner to fund further drilling at the Toby prospect, and have conducted additional geophysical modelling studies of the target structure aimed at refining the definition of subsidiary gravity anomalies.