During the 2012-2013 licence reporting year, work conducted in this the 21st year of tenure at Alford consisted of: - commissioning a consultant to undertake image processing and 3D inversion modelling of available gravity and magnetic datasets...
During the 2012-2013 licence reporting year, work conducted in this the 21st year of tenure at Alford consisted of: - commissioning a consultant to undertake image processing and 3D inversion modelling of available gravity and magnetic datasets for the licence area; - acquisition during March 2013, along 12 traverses across the Glenrae and Alford East prospects, of a detailed dipole-dipole IP survey having 13.1 line km coverage, which included 2.15 line km acquired within PM 268 (W.E. Avery's construction materials pit and surrounds - for mining sand and calcrete); - regional and infill bedrock sampling aircore drilling of 241 inclined holes during January-April 2013, for a total penetration of 17,493 m; - diamond drilling of 5 inclined HQ/NQ2 cored holes for 1504.1 m, to test the aforementioned two prospects for copper-gold mineralisation with IOCG affinity; - making a geochemical interpretation of downhole wireline logged analytical spectral device (ASD) scans of aircore bottom-of-hole in situ Palaeoproterozoic metasedimentary bedrock; - laboratory assaying of 1-metre interval drill core samples; and - undertaking petrographic thin section examinations of 26 selected drill core samples of contact metasomatised metasediments. Multiple significant mineralised intercepts were made by the aircore holes, often straddling saprolite / saprock boundaries. A number of fresh basement rock intercepts were made on PM 268. The Tickera Granite was not penetrated by any of the diamond holes. The diamond drilling produced best mineralised intercepts of 40.8 m @ 0.42% Cu and 0.07 ppm Au from 90 m in hole ALDDH017 (Alford East), and 20 m @ 0.27% Cu and 0.16 ppm Au from 196 m in hole ALDDH021 (Glenrae). Overall, the drilling results showed that a strong structural control to primary mineralisation exists. Secondary mineralisation occurs as a supergene blanket that seems to be localised by the water table and other formational waters. Importantly, significant mineralised intercepts or anomalous copper and gold dispersions at depth do seem to be overlain by supergene copper and gold, as witnessed by the aircore drilling. During the 2013-2014 licence reporting year, the work conducted included: - acquisition over the period December 2013-January 2014 of part of a detailed ground gravity survey, on EL 5212 comprising 1184 stations read at 200 m x 200 m spacing over all targeted prospect grids excepting the Alford East grid, which was surveyed at 50 m station spacing along east-west lines 400 m apart. The remainder of the survey was located on Sandfire's southwards adjoining EL 5273 Anna Villa; - acquisition over the period December 2013-February 2014 of a detailed, 22.9 line km dipole-dipole IP survey at Alford East and four other prospects, being those same five covered by the above gravity survey. The 17 lines profiled were not regularly spaced apart, but were variably separated by up to 1200 m. Recording stations were placed at 50 m intervals along the E-W or NE-SW orientated lines. Consultant geophysicist David McInnes was retained to process the survey data as soon as they were produced, to use for generating enhanced visualisation map images and resistivity and chargeability inversion sections that would help Sandfire to refine drillhole locations; and - ongoing exploratory aircore and diamond core drilling: 85 inclined aircore holes for 5364 m to continue bedrock geochemical sampling, plus 4 inclined HQ/NQ2 cored holes for 1483.4 m to test gravity/magnetic and IP chargeability targets. The drillholes put in during 2014 confirmed that copper mineralisation in fresh bedrock can be identified by anomalous copper in the overlying oxidised zone. The diamond drilling produced a best mineralised intercept of 10.0 m @ 0.56% Cu and 0.19 ppm Au from 140 m in diamond hole ALDDH024 (Alford East). In June 2014, consulting geologist Toby Davis submitted a report commissioned by Sandfire about the structural evolution of basement within the Alford Project area. His interpretation was that overall, the rocks there exhibit low bulk strain produced over time by five deformational events. Skarnification, the emplacement of copper mineralisation and the youngest deformational event were interpreted to be coeval: however, the role of structures in controlling the localisation of copper sulphides and skarn alteration assemblages appeared to probably have been quite minor. A review of the progress of the Alford Project farminee's work was completed by Kelaray during July 2014. Most of the drilling done by Sandfire for exploring the Alford Project licences had been located at the Alford East (most intense calc-silicate skarn) and Glenrae (most intense haematite-altered breccia) prospects. The potential of a near surface IOCG deposit to occur at Alford East was deemed to have been fully tested, and the prospectivity for any significant, economic copper deposit to exist there was now considered low. Disappointingly, the iron metasomatosed Glenrae diatreme had been found to be un-mineralised in terms of economic metals; their lack within it could not be accounted for, given that the structure represents a perfect potential host. A drilling knowledge gap analysis was undertaken, and several possible new targets elsewhere on the project ground were proposed for investigation. [After July 2014, ongoing work performed on the Alford Project became jointly reported to DSD under the terms of an amalgamated expenditure agreement made with the department at that time. Project joint reports subsequently submitted to DSD by the JV partners in 2015 and 2016, and later by Kelaray acting alone, are held separately in Env 12794.]
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