A licence consisting of three separate small sub-blocks that cover a large number of freehold broad-acre farms in the Bute - Agery - Moonta South district has been explored for possible buried economic IOCG mineralisation, which may have formed on...
A licence consisting of three separate small sub-blocks that cover a large number of freehold broad-acre farms in the Bute - Agery - Moonta South district has been explored for possible buried economic IOCG mineralisation, which may have formed on or near the interpreted Workuna - Kainton Breccia Trend, a basement structure that Investigator Resources (IVR) had identified previously whilst it was exploring in its adjacent EL 4278 The Hummocks. This structure was thought by IVR to have a strong structural relationship with the IOCG prospective Pine Point Fault that runs along the eastern side of Yorke Peninsula. IVR took up the subject Port Hughes ground parcel because it appeared to contain, in the southern sub-blocks, several magnetic features that resembled the aeromagnetic high anomaly present at the recently discovered Hillside IOCG deposit. No field work took place during licence Year 1. Instead, IVR's activities comprised: - landholder liaison and the negotiation of an access agreement with one specific landholder whose property is located near Bute; - conducting a review of previous exploration, including the compilation of North Broken Hill's historic auger soil geochemical sampling data into digital format; - inspecting stored drill cuttings samples and diamond core of 1974-drilled hole SADME Bute DDH12 held at the DMITRE State Core Library; - making plans to acquire a ground gravity survey over the Wehr prospect, which is located immediately to the north-west of Bute township; and - making plans to also conduct a soil geochemical survey over the Wehr prospect. During licence Year 2, IVR commenced its field work as follows: - In December 2011, a small detailed gravity survey totalling 608 stations was read over the Wehr prospect on a regular 100 m x 100 m grid. No obvious discrete gravity anomalies were disclosed, but some possible structural discontinuities were interpreted; - this was complemented by soil sampling over the gravity grid for laboratory partial leach analysis (608 samples collected on 100 m centres). The assay technique used was relying on the presence of relatively thin Neoproterozoic and Cambrian (and younger) cover over the Palaeoproterozoic basement, e.g. as in SADME Bute DDH12, where there is only a 4 m thick transported cover over saprolite, saprock and haematitic breccia. A consistent silver anomaly was revealed, but this was later discounted after doing aircore drilling, with it then explained by IVR as reflecting vertical migration of Ag ions from the weathering interface at ~30 m depth on the gently easterly-dipping sulphidic (and weakly silver-bearing) Neoproterozoic Tapley Hill Formation; - aircore exploratory drilling of the Wehr prospect was undertaken in June-July 2012, with 44 vertical holes completed for a total penetration of 1299 m. Drill targets were based on the combined results of the gravity and soil geochemical data, and the existing magnetic data (Note that the four holes BWAC031-BWAC034 were drilled just inside of adjoining EL 4278 The Hummocks, also held 100% by IVR. They are included in this report as they were part of this drilling programme, and because they were drilled across the best Ag-in-soil anomaly). Minor amounts of low level Ag and Cu were encountered in several holes; however, the contracted aircore drill rig that was used proved to be mostly ineffective at penetrating through the Tapley Hill Formation (THF) in many places. Past exploration had shown that the THF is often sulphide-rich, particularly near the base, often with several ppm Ag-Pb and Zn. Previous drilling in the Bute area had largely focussed on this in an attempt to discover Mississippi Valley style Ag-Pb-Zn mineralisation in the THF; - a helimag survey was flown across the whole tenement in early November 2012, along east-west flight lines 100 apart, using a sensor nominal terrain clearance of 25 m. A small area over and to the east of the town of Bute was omitted from the survey (but note that this survey also covered significant areas of EL 4278). Early modelling results for the newly acquired aeromagnetic data defined a number of targets on all three licence sub-blocks, and plans were made to drill test these as soon as practicable. During the third licence year, IVR performed the following: - a further review of past explorers' stored drill cores and their associated data, for samples stored at both the DMITRE Glenside and Moonta Core Libraries; - making ongoing interpretations of aeromagnetic and radiometric data based on refining of geophysical models as more data was added to them. A common conclusion drawn was that previous exploratory drillholes close to anomalies of interest invariably were not carried deeply enough identify the nature of now inferred basement sources to these anomalies; - planning for acquiring a second ground gravity survey along roadsides to the south of Bute township, to delineate if dense basement material is associated with a potential IOCG - related helimagnetic anomaly named the Reliance prospect; and - conducting discussions [partly tinged by much acrimonious resistance] with a number of landholders in the district regarding access for on-ground exploration on their cropped lands in the 2013-2014 summer, after harvest. During licence Year 4, slow but gradual progress was made in delineating an IOCG drill target at the Reliance prospect centred 4 km south of Bute. During December 2013, the needed gravity data was acquired at 100 m and 200 m station spacings along local roadsides only (i.e. working on unfettered public land), with 224 stations read as part of a larger gravity survey programme that took place mainly on the adjoining EL 4278 The Hummocks. Subsequent geophysical modelling of the merged regional and new detailed gravity by IVR's consultant Matthew Hutchens reinforced the licensee's expectation that significant epithermal and magnetite skarn type copper-gold mineralisation might be found in untested, apparently variably metasomatised and demagnetised reactive basement metasedimentary rocks in this location. Also during this year, IVR decoded to trial using field portable XRF spectrochemical scanning instruments to geochemically “sample” soils along roadside traverses made across parts of the tenement, since this would avoid the complications of gaining access with the landholders, and especially because Adelaide Resources had lately reported a technical success with using the method on its nearby tenements (viz. discovering the Five-Ways copper occurrence). So, following on from the gravity survey, a total of 433 FPXRF soil sample readings were taken using a Niton brand instrument, from samples collected generally at 200 m spacing. Unfortunately, IVR afterwards considered the sampling results as inconclusive, as there was too small a range of values recorded in most elements for the concentration “highs” to be considered as little more than being marginally above background (or marginally above the detection limit). Nevertheless, some elements with poorly discernible trace anomalism (silver, arsenic, copper, thorium, zinc and zirconium) were plotted by IVR to show their possible dispersive distribution in soils within the Bute and Agery licence sub-blocks. IVR remained hopeful that copper could be one pathfinder element that the FPXRF unit can reliably detect, and consequently planned further FPXRF sampling trials for 2015 within the Moonta sub-block and as extensions within the Agery sub-block. Ongoing hostility and intractability from local Bute landowners towards the company meant that it could not legally progress its intent to drill the Reliance prospect in the ensuing almost three years, before the decision was reluctantly made to surrender licence tenure.
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