Annie Spring EL 9413 third and final report for the year inding 15-05-1999

Abstract

Initial evaluation of the regional aeromagnetic data suggested a similarity to the Eastern Succession of the Mt Isa Block and potential for mineralisation associated with discreet magnetic bodies. Also the potential for unconformity related uranium mineralisation was recognised. The contact between the Arunta Block and Ngalia Basin is structural, thus down grading the perceived potential for stratabound copper mineralisation. A detailed aeromagnetic survey of four anomalous areas was undertaken in year 1, whilst in year 2, 4500 line km of detailed airborne radiometric/magnetic survey was completed. Three magnetic anomalies were further evaluated by ground magnetic and gravity surveys. Modelling of the anomalies suggested that a BIF is the probable source and required testing by diamond drilling. Magnetic anomaly AS1 was drilled to 177.9m and a raft of BIF forty meters wide was intersected within a megacrystic granite. No anomalism for any of the elements analysed was detected. Magnetic anomaly AS2 was evaluated by a core hole drilled to 251.8m and intersected siltstone and fine sandstone with four BIF zones to 9m wide obtained. The BIF was magnetite rich with chert veins and pervasive chlorite alteration; associated pyrite assays included 1100ppm As, Au to 0.1 g/t and 0.49% P. It was recognised the Mg chlorite alteration and hematite cherts associated with reactive lithologies have strong affinites to the Kintyre uranium mineralisation in WA, hence the potential for uranium was promoted and the licence was covered by a detailed airborne radiometric and magnetic survey. Assessment of the radiometric data showed four distinct zones. Zone 1 corresponds to a particular horizon within the Mt Eclipse Sandstone and includes the Bigrlyi uranium deposit; zone 2 is associated with the main Patmungala Beds with moderately elevated uranium values; zone 3 contained a number of uranium anomalies sourced by the Yaloogarie Granite, zone 4 contained four groups of uranium anomalies where the Patmungala Beds are in contact with the Yarunganyi Granite. During year 3, fifty-one radiometric anomalies were recognised, of which nineteen were followed up on the ground. Within zone 1 seven anomalies were rock chip sampled and included the Bigrlyi deposit. None of the anomalism within Zone 2 warranted follow up. Within zone 3 a singular hot spot anomaly obtained 2550 ppm U and is associated with carnotite. Within zone 4 six anomalies were followed up with visible Torbernite observed within a narrow ferruginous quartz filled fracture. Six magnetic dipole anomalies within a radius of 2 km were indentified and were further evaluated by ground magnetics and suggested possible kimberlitic diatremes. Surface sampling recovered chromites of possible kimberlite affinities. Seven RC holes were drilled into the anomalies - six holes intersected fine grained magnetite rich basalts and the other was within biotite granite with some magnetite.