In a search for possible buried Palaeoproterozoic unconformity - related sedimentary uranium deposits over an area east of the Darke Range, an ongoing programme of exploratory work has included geological mapping at 1:25,000 scale, analysis of 205 geochemical samples, and the drilling of 20 RAB holes (total 592 m) and 3 diamond holes (total 300.8 m). Initially, an aerial geophysical survey detected but a few significant radioactivity anomalies in areas of inferred limited source potential (being associated with pegmatitic segregations in basement gneiss and with Tertiary laterites). Following this, the regional strike of both the prospective Early Proterozoic Katunga Dolomite and graphitic Mangalo Schist was extrapolated into the area of poor outcrop near Cockabidnie, where these units are overlain by a thin cover of Middle Proterozoic Blue Range Sandstone. Follow-up work detected a significant radon anomaly associated with a zone of intense haematization of sandstone and schists located adjacent to the unconformity, as well as disclosing anomalous radium, radon, thorium and uranium values in drill cores and in groundwater. Further drilling and trenching is recommended to test this radon anomaly and the zone of haematized sandstone.