An area located near the south-eastern margin of the Musgrave Province, in the eastern and northern Everard Ranges about 100 km west-northwest of Marla, wholly within the APY Lands, has been explored for possible economic nickel-copper-platinoid...
An area located near the south-eastern margin of the Musgrave Province, in the eastern and northern Everard Ranges about 100 km west-northwest of Marla, wholly within the APY Lands, has been explored for possible economic nickel-copper-platinoid group elements (PGE) sulphide deposits that may be associated with mafic and ultramafic magmatic rocks of the Giles Complex of the Warakurna Large Igneous Province (LIP), and also the older mafic granulite of the Birksgate Complex. The potential for such deposits to occur in the latter, 1200-1300 Ma mafic granulite was recognised following the discovery of the Nova-Bollinger deposit by Sirius Resources NL in July 2012 within the Albany - Fraser Province of Western Australia. The crustal scale structures within that region have a NE-SW orientation, with transform (second order) structures of NW-SE orientation. These transform structures host the Nova-Bollinger mineralisation. SA's eastern Musgrave Province contains the same age rocks, i.e. granulite facies meta-gabbro (mafic granulite), which are cut by crustal scale structures having the same favourable orientation (SSW-NNE). Following the grant of the subject licence, which formerly was part of a group of 14 licences known as the Musgrave Project, it was operated by Independence Group NL until it was transferred to Musgrave Minerals in late 2010. Independence Group NL and Musgrave Minerals Ltd have spent a total of $925,392.81 on the tenement over the seven year period of tenure from 19/10/2007 to 18/10/2014. The bulk of this expenditure was spent on surface geochemistry, heritage clearances, IP surveys and RC drilling. The limited amount of work completed on the Everard Park ground failed to find any significant mineralisation. Much of the licence area is overlain by >100 m thick Quaternary cover associated with dense vegetation, making on-ground access difficult. The mapped outcrop mainly comprises either non-prospective Pitjantjatjara Supersuite granite, Birksgate Complex felsic granulite, or Tertiary silcrete and ferricrete. Mafic dykes of both Amata and Alcurra age, along with Birksgate Complex mafic granulite, constitute only a minor component of the outcrop that was seen across EL 3194. The south-eastern corner of the tenement occurs on the margin of the Officer Basin, where the Blue Hills Sandstone overlies the Proterozoic basement. Possible sulphide mineralisation of the type that was sought may exist under cover in the central western part of the licence area , associated with an interpreted Birksgate Complex mafic intrusion. That interpretation is based on several mafic xenolith inclusions identified within outcrops of Pitjantjatjara Supersuite granite which are spatially associated with a large gravity high. However, if any such mineralisation is associated with this inferred intrusion, it is considered to be likely to occur much too deeply for practical exploration at this stage. Budgetary constraints and competing project prioritisation were the causes of many prospective areas remaining untested. Overall, on the information available it was judged that the tenement has fairly low prospectivity for economic Ni-Cu sulphides relative to the other Project ELs held by Musgrave Minerals. Due to these reasons, it was decided late in 2014 to allow tenure to lapse. Preliminary interpretations of satellite hyperspectral imagery (Aster and SPOT5) were made during 2007 to try to delineate the extent of Proterozoic mafic and ultramafic intrusions in the Everard Ranges, with the aim of doing a petrological assessment of their nickel sulphide potential. A number of mafic dykes were recognised to outcrop in the south-west of the ranges, one off which showed evidence of magmatic layering. No large Giles Complex intrusions were identified. Exploratory 1:100k geophysical and geological mapping of all of the basement rocks on EL 3954 was undertaken by Independence Group soon after licence grant, but the thick and widespread cover made the attempt largely unsatisfactory. It was found that although the available magnetic data was of reasonable quality, the gravity data was sparse, making it difficult to prioritise areas undercover for follow up. Although no sulphides were disclosed in the outcropping mafic dykes, it was thought that ground EM traverses could be warranted across the larger dykes. Magnetic features identified in the centre of the tenement were followed up with hand auger sampling (34 samples), however this sampling was ineffective due to the depth of cover. During May through September 2008, Independence Group conducted a regional ground gravity survey totalling 1728 stations at 1 km x 1 km grid spacing, which included an area on EL 3954 referred to as Block 7. This part of the survey was later infilled to 500 m x 500 m grid spacing, for a combined relevant total of 113 stations. The survey defined a large gravity high located just south of the Mimili Community. Reconnaissance soil sampling was also performed on Block 7 using the cleared gravity grid, with 17 samples collected at 1 km x 500 m spacing. Elsewhere within the subject licence area, over the seven years of tenure reported herein, 79 rock chip samples, 34 hand augered coarse lag samples, 120 magnetic lag samples and 336 surface coarse lag samples were also collected for assaying, mostly from over and around mafic dykes. Although dykes were identified that have interesting features including magmatic layering and contamination (i.e. assimilation of country rock), for the most part their nickel and copper assay results did not exceed background values for mafic/ultramafic rocks. Musgrave Minerals flew an 1089.9 line km airborne VTEM survey over the Moorilyanna prospect area in November 2010. Of this survey coverage, 96.15 line km crossed into EL 3954, defining a single target there. The work was followed up in 2011 by conducting ground EM survey traverses over the Moorilyanna prospect area, which included profiling the single AEM anomaly on EL 3954; this involved half of a traverse line, for 0.6 line km. No discrete bedrock conductor was found to be associated with the AEM target. During the fifth year of tenure of EL 3954, with a decision pending on whether to renew the licence for a second term, Musgrave Minerals' attention became drawn to the indicated copper and gold mineralisation potential of the large Picon mafic dyke located in the north-east of the area, straddling the boundary between its ELs 3954 and 3955. Earlier rock chip sampling of an outcrop there had returned anomalous values of 0.1% Cu and >0.5 g/t Au from two separate single samples. In March 2012, Musgrave Minerals performed part of an IP survey across this Picon dyke outcrop, recording 15 stations along 1.5 line km, which revealed a significant IP response. The target portion lying within EL 3954 was then investigated during April 2012 by RC drilling of 2 inclined holes for a total penetration of 210 m. The best drillhole intercepts obtained were in hole MOORC012, being 3 m @ 0.15% Cu and 0.5 g/t Ag from 41 m depth, plus 3 m @ 0.13% Cu from 103 m depth. But the drilling failed to intersect significant gold (the highest value was 16.7 ppb Au). It is now believed that the anomalous rock chip gold result may have been discrete and limited in origin to some quartz veins developed in the sheared margin of the dyke. Drilling of the Picon dyke slightly to the north, on EL 3955, intersected 1 m @ 0.54% Cu and 153 ppb Au in hole MOORC014. Work undertaken during the last two years of tenure, for the renewed EL 5174, consisted of additional soil and rock chip sampling. No results warranting more investigation were obtained.
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