A licence area now consisting of two separate small blocks located about 60 km west of Whyalla was taken up, along with other ground in the region, because it is thought to have potential for the discovery of uranium associated with Olympic Dam...
A licence area now consisting of two separate small blocks located about 60 km west of Whyalla was taken up, along with other ground in the region, because it is thought to have potential for the discovery of uranium associated with Olympic Dam style IOCG deposits. There may also be potential for vein type fault-related deposits, and for sedimentary uranium deposits. Geologically, the area lies near the southern margin of the Gawler Range Volcanics Domain, in a zone with known intrusions of Hiltaba Suite granites, such as the Charleston Granite. At the time of the Hiltaba Suite thermal event, this would have been a shallow, sub-volcanic igneous environment, similar to the geological setting of IOCG deposits at Olympic Dam, Prominent Hill and Carrapateena. Initial work comprised the acquisition of additional gravity coverage to complement a recent PACE-managed regional gravity survey which had covered only a small part of the tenement. During September 2006, 167 new stations were read on a 1 km x 1 km grid. This work revealed a significant 3 mGal residual positive gravity anomaly near Waxings Dam, lying ouside of but near the margin of a large magnetic anomaly. It was decided to acquire further more detailed gravity data here to help define the structure of the interpreted gravity source body. Accordingly, during January-February 2008, 196 stations of infill gravity were read on a 250 m x 250 m grid at the Waxings Dam prospect. The work confirmed the presence of a 2.5 mGal residual gravity anomaly, approximately 2 km long by 1 km wide, characterized by a NW trend with the steepest gradients on its southern margins. Geophysical data modelling indicated that the depth to the source body should lie at 750 m depth or slightly shallower, depending on the actual densities of some other small dense units recorded in the upper 500 m of the basement. Four alternative drill sites were proposed to test different aspects of the gravity model where they interact with regional magnetic features. Southern Uranium chose just one of the recommended drill sites as a priority, because it would test a subsidiary gravity high associated with a NE structural offset in the main NW trending magnetic lineament, which latter was though to be a fault into which a Hiltaba age granite body had intruded, a short distance away to the south-east. The preferred drill site was located approximately 34 km north-northwest of Kimba. Here inclined diamond drillhole WDDH01 was drilled during February-March 2008 to a total depth of 952 m, following completion of an RC pre-collar to 214 m hole depth. The hole was directed towards 30 degrees True azimuth, with a dip of 60 degrees. No significant mineralisation was encountered in WDDH01. The hole entered saprolitic schistose basement metasediments of the Hutchison Group at 4 m depth, and passed into fresh bedrock at 135 m depth. It then remained in weakly to moderately foliated metasediments, containing frequent coarse-grained garnet pegmatite layers plus occasional dolerite dykes and calc-silicate bands, until around 775 m depth. There the lithology changes to a migmatitic and less variable quartz-feldspar-biotite-garnet gneiss (?Sleaford Formation), which continued to the end of the hole. Samples of composited 4-metre intervals of all of the precollared RC drill cuttings, plus 109 selected 1-metre interval chip samples of the recovered NQ2 drill core, were submitted for assay in June 2009. Southern Uranium later reviewed the drillhole assay results, but did not report any conclusions. In November 2008, the licensee began a programme of reconnaissance soil sampling on the tenement, initially covering readily accessible areas and later entering the remaining parts on freehold land where access had to be negotiated. A total of 183 soil samples were eventually collected, on a 1 km x 1 km grid. This grid was later infilled in four anomalous areas in mid-2009 by the collection of a further 224 soil samples at 500 m x 500 m spacing. In August 2009, Southern Uranium reviewed its surface geochemical survey results, and identified a possible Au-Ag-Cu target within the southern sub-block of the tenement. To confirm the anomaly's integrity, it was planned to do some additional soil sampling there at 250 m x 250 m spacing. However, difficulties arose with gaining permission for on-ground access from one of the private landowners, and the work had to be postponed.
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