An area centred ~50 km south-east of Manna Hill township on the Barrier Highway has been taken up to explore for possible economic buried epithermal, VHMS style copper-gold or other base and precious metal mineralisation which could have formed...
An area centred ~50 km south-east of Manna Hill township on the Barrier Highway has been taken up to explore for possible economic buried epithermal, VHMS style copper-gold or other base and precious metal mineralisation which could have formed within folded basal Adelaidean volcanic rocks and associated volcanogenic sediments existing in a possible late stage graben setting adjacent to the south-eastern margin of the younger, Ordovician age intrusive Anabama Granite pluton. Work undertaken during the first licence year comprised a desktop review of relevant past exploration results, the interpretation of available geophysical data, and the compilation of existing drillhole data into digital format. No work was undertaken during the second year of tenure owing to budgetary constraints. Plans were made to conduct surface geophysical surveys to try to detect buried primary sulphide mineralisation in the vicinity of the Anabama mine lode and further to the north-east along an interpreted north-westwards dipping fault. During the third licence year, Goldrap acquired a dipole-dipole IP survey during August 2003 along 5 NW-SE lines spaced 300 m apart crossing the Anabama mine prospect, for a total of 7.5 line km of chargeability readings. 2D modelling of the IP survey results was completed by Zonge Engineering and Research Organisation (Australia) Pty Ltd, and 3D modelling of these IP results was completed by geophysicists of Geophysical Resources and Services Pty Ltd using BlockViewer computer graphics software. Goldrap's previous compilation and interpretation of data for the Anabama mine prospect had indicated that here very little attention has previously been directed at testing for higher-grade primary copper mineralisation which might exist below or adjacent to the shallow oxide copper resource. While it was likely that only low-grade primary copper mineralisation might exist, it was decided that some testing of this target was required. The review work had also highlighted potential for extensions of the copper oxide - mineralised zone into the north-east of the prospect, where an earlier drillhole RC95AB15 had intersected 30 m @ 0.76% Cu, because no further RC drilling had been carried out to the north-east of this intersection. A proposal was made for initially drilling three step-out RC drillholes into the chargeability targets defined in this area. During the fourth licence year, the planned exploratory drilling was performed during October-November 2004, when 4 vertical or inclined RC holes were completed for a total penetration of 944 m. In general the mineralisation encountered was sparse and weak (only a single 4-metre composite drill cuttings sample yielded >100 ppm Cu); just one significant mineralised intercept was made, in vertical hole ARC0404, within a shear zone in altered phyllitic siltstone that was intersected over the depth interval 240-248 m, which contained up to 10% sulphide including 1-3% chalcopyrite, plus 30% iron oxides and 50 % quartz. Drill chip assays of 4-metre intervals of the altered country rock above this zone, starting at 140 m depth, returned an average grade of 56 m @ 0.43% Cu, consistent with grades seen in earlier explorer's shallower drillholes in the vicinity. Hole ARC0401 also encountered a possible shear zone returning 12 m @ 0.63% Cu from below 210 m depth, that underlies altered and weakly sulphidic siltstone/psammopelite rock extending downwards from 173 m. It was concluded by Goldrap that both of these holes had tested the prospect's Main zone of previously identified mineralisation, from 173-222 m in ARC0401 and 212-260m in ARC0404. The underlying shear zone was inferred to have a dip of ~55 degrees North. During the fifth licence year, no field work occurred; activity comprised the assaying during December 2004 - February 2005 of a subset of the additional, 1-metre interval drill cuttings samples that had been retained from holes ARC0401 and ARC0404. The results of the more precise assaying of 76 such samples largely confirmed the results obtained from the 4-metre composite samples of these two holes, i.e. the presence of a 60 m thick lens of sulphidic rock grading up to ~0.4% Cu. During the sixth licence year, on renewed EL 3548, after its sale to Diatreme Resources, the new operator's consultant geologist made a field reconnaissance visit and collected 35 soil calcrete geochemical samples as part of orientation sampling over historic RAB drillhole copper intercepts. A single panned sample of heavy mineral concentrate was taken from a surface drainage channel having an airborne radiometric thorium signature, for determining its HM mineralogical composition. During the seventh licence year, Diatreme acquired a helicopter-borne aerial EM (VTEM - Versatile Time domain ElectroMagnetic) survey of 970 line km during late February 2008, which covered most of its Anabama Project ELs 3548 and 3923 along NW-SE aligned flight lines spaced 200 m apart.
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