Exploration carried out over the northern Peake and Denison Ranges since 1993 has targeted possible large-scale Proterozoic ironstone-hosted Cu-Au deposits considered to have formed in stratigraphic/structural settings similar to those seen around commercial deposits of the Mount Isa Inlier, while not ignoring the rocks' more usual correlation with those successions present in the Whyalla and Moonta areas of the eastern Gawler Craton. Metamorphosed volcanosedimentary and plutonic units in the four main basement inliers have been studied by a variety of field mapping, geochemical and geophysical methods to delineate likely copper and gold mineralised prospects suitable for drilling. Under tenure of EL 1844 in 1994-1995, Pancontinental performed geochronology of rock samples, plus interpretations of Landsat and open file aeromagnetic data for the now relinquished licence subareas. Next followed a period of three years with no work carried out, until July 1998 when BHP Minerals farmed into EL 1925. BHP undertook regional and detailed gravity surveys, plus ground magnetics and ground EM traverses, and completed one shallow diamond precollar hole west of Davenport Creek on a 4.2 mGal large gravity anomaly with no associated magnetic response. This drillhole was aborted in silicified Algebuckina Sandstone at 113.7 m total depth, well short of its Palaeoproterozoic basement target. The local geological structure was interpreted from the gravity data as being an approximately 300 m deep graben within the Denison Inlier that is infilled with Mesozoic and possibly also Neoproterozoic sediments. On 12/5/2000 Rio Tinto entered the Peake and Denison joint venture, and commenced a re-interpretation of the gravity and airborne magnetic data, besides acquiring new gravity and IP line coverage of prospective anomalies, including the Mount Charles no. 4 gravity anomaly inconclusively drilled by BHP. Anomalous gravity and IP responses were recorded over this latter gravity feature, designated the Eitzen prospect, which still require follow-up investigation. In the covered areas to the west of the exposed basement inliers, Rio Tinto completed a 1 km x 1 km spaced gravity survey in July 2001, seeking evidence of density contrasts in the concealed basement possibly created by massive iron-flooded alteration systems. The survey identified a prominent NNW gradient which separates subdued gravity responses in the SW from elevated responses in the NE. This feature can be explained by a horst and graben model, with the southwestern edge of the main uplifted basement block coinciding to the position of maximum gradient. The relief (up to 7 mGal) in Bouguer gravity on the upthrown block is taken to represent variations in basement density, basement depth under cover, or both. However, no prospective high gravity points are located within the relinquished portion of EL 2620. Rio Tinto has concluded that residual potential remains for small to medium-sized IOCG targets around the margins of the exposed inliers in places with less than 200 m of cover, but considers that these are no longer of immediate interest to it. Accordingly, it farmed-out the licence to Phelps Dodge in 2003. Recent work by Phelps Dodge has comprised reprocessing of aeromagnetic and gravity data, leading to a new magnetic and structural interpretation of the project area. Again no targets were defined in the now relinquished portions of the licence.