Stratabound, chemically precipitated Telfer - type replacement style vein gold was the target of exploration undertaken over an area 25 km north-west of Yunta, which contains good exposures of Neoproterozoic Umberatana Group clastic metasediments...
Stratabound, chemically precipitated Telfer - type replacement style vein gold was the target of exploration undertaken over an area 25 km north-west of Yunta, which contains good exposures of Neoproterozoic Umberatana Group clastic metasediments that carry such gold mineralisation at the nearby Waukaringa and Ajax gold mines. Work completed included 1:10,000, 1:20,000 and 1:50,000 scale geological mapping and associated rock chip, soil and stream sediment sampling (in total 689 samples), plus the drilling of 5 inclined diamond holes (total penetration 2148 m) and 7 inclined percussion holes (total penetration 1548 m). The drilling failed to find significant gold intercepts, but elevated Cu, As and Mn were detected over the depth interval 20-80 m in percussion hole MP5, drilled along strike 5.5 km east of the principal Waukaringa workings, near the nose of the Waukaringa Syncline. Because of encouraging assay results for gold from 48 stream sediment samples taken from areas underlain by the Appila Tillite in the Black Hill Anticline, the gold search target became orientated towards a placer type deposit. Seventeen stratigraphic profiles totalling 32 line km were made along this anticline, to log facies variations and zones of alteration in the tillite. Ridge and spur rock chip and soil sampling of ferruginous, quartz-goethite veined diamictite and sandstone on the northern limb of the anticline (65 samples) reported gold values of up to 1.4 ppm Au. Subsequent hand panning of anomalous stream sediment sample sites gave more concentrated gold values of up to 120 ppm Au, with visible flakey coarse gold. It was concluded that the source of this gold predominantly lies within concordant to discordant ferruginous quartz veins which tend to be common toward the centre of the anticline, and which were probably formed by mobilisation of hydrothermal fluids during the Delamerian Orogeny. As an adjunct to the gold search, 33 stream sediment heavy mineral samples and 17 loam samples, of 20 kg each, were collected to test the kimberlitic diamond potential of the licence area. No kimberlite indicator minerals were observed.
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