An area with poor basement outcrop located approximately 60 km south of Tarcoola, which largely lies within the north-eastern corner of the Yellabinna Regional Reserve, is being explored primarily for possible economic fault or breccia-hosted...
An area with poor basement outcrop located approximately 60 km south of Tarcoola, which largely lies within the north-eastern corner of the Yellabinna Regional Reserve, is being explored primarily for possible economic fault or breccia-hosted mesothermal gold +/- base metal mineralisation in likely multiphase Mesoproterozoic felsic volcanic and granitoid intrusive rocks which are juxtaposed against or are cross-cut by long-lived deep crustal faults (Oolabinna and Koonibba), and lie near two major regional shear zones (Yarlbrinda and Yerda). The subject tenement adjoins the western boundary of Helix Resources' EL 2697 Lake Everard, upon which lies the Tunkillia prospect. During March 1997, a 50-50 joint venture was formed between Helix and Acacia Resources Ltd (the Gawler Craton Joint Venture). In December 1999, AngloGold Ltd launched a successful takeover bid for ownership of Acacia, which then became AngloGold Australasia Ltd. Early work on the licence area comprised reconnaissance and detailed calcrete sampling, starting with 194 samples collected on a nominal 1 km x 1 km regional grid, then 561 more samples were taken on 500 m x 500 m spacing to infill anomalous areas, and these were followed by a further 382 infill samples collected at 200 m x 200 m spacing, for a total of 1137 samples. From this work, four significantly anomalous (+5 ppb Au) gold-in-calcrete localities were identified, which also had distinctly elevated values for some other trace elements. Plans were made by AngloGold to do shallow RAB drilling to sample the bedrock at the Kremmen prospect, but protracted Native Title land access negotiations caused this drilling programme to be postponed for two years, at the end of which time AngloGold decided to leave the JV with Helix. Subsequently, 325 additional calcrete samples, nominally spaced at 50 m intervals, were collected by Helix early in 2001 along eleven traverses in order to “tighten up” the RAB drilling targets. Some coherent anomalism peaking at 15.3 ppb Au was identified at Kremmen, within a 400-500 m wide by 1500 m long anomalous envelope. A highest value of 18.9 ppb Au was measured by Helix at the smaller, 400 m x 100 m Droog anomaly, but the tenor of results there may have been influenced by sampling calcareous soils rather than calcrete. During March 2005, Minotaur Resources entered into a joint venture with Helix to explore on several adjacent western Gawler Ranges tenements including EL 2854, seeking possible buried IOCG mineralisation as well as shear zone - related Tunkillia style gold. During April 2005, the South Australian Government through PIRSA acquired 2 km x 2 km spaced regional gravity data in the Yellabinna district to aid its promotion of the mineral potential there. A subset of 525 gravity stations was read on EL 2854 and the data then was made publically available. To benefit further from this programme, Minotaur undertook infill gravity coverage of the interpreted anomalous areas during July 2005, acquiring an extra 60 stations at 500 m x 500 m spacing in the north of the EL. No significant gravity high anomalies were revealed, as might indicate a dense basement with IOCG potential, although the PIRSA data had disclosed several discrete low amplitude (1-2 mGal) anomalies lying within the tenement, with two in the south having some magnetic anomaly associations possibly due to buried plutons, and also being cut by subtle north-west trending fault signatures (?mafic dykes). Nevertheless, Minotaur submitted to PIRSA for consideration a number of DEF-supported proposals for aircore/RAB bedrock drilling of several gold-in-calcrete anomalies that the previous explorers had found. As part of Minotaur's uranium search activity being pursued by its subsidiary Toro Energy, plots of night-time thermal imagery of the ground surface were used together with gravity data to try to delineate the locations of buried Tertiary palaeochannels. Subsequently, during August 2006, an airborne EM survey was flown over ~80% of EL 2854 by Toro to assist in defining depth to basement and outlining prospective parts of the palaeochannels, besides identifying any shallow basement conductors. Plans were made to acquire additional gravity coverage, including microgravity traverses across AEM anomalies, and for doing surface geochemical sampling, but as of the expiry date of EL 2854 the work remained contingent upon re-issue of the exploration tenement for a third term and the prior grant of environmental protection approvals.
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