EL 3438 Muckanippie is located in the northern Gawler Craton, on the western margin of the Gawler Range Volcanics Domain, and is centred approximately 60 km north-west of Tarcoola. Basement outcrop on the licence area is sparse, with a thin cover...
EL 3438 Muckanippie is located in the northern Gawler Craton, on the western margin of the Gawler Range Volcanics Domain, and is centred approximately 60 km north-west of Tarcoola. Basement outcrop on the licence area is sparse, with a thin cover of Mesozoic Algebuckina Sandstone and Cainozoic sediments in most places. The known and inferred basement geology consists mostly of Archaean gneissic metasediments of the Mulgathing Complex. These are overlain by units of the Mesoproterozoic Gawler Range Volcanics. The central part of the area is dominated by the Muckanippie Anorthosite Complex, an intrusive rock massif covering an area of approximately 800 square km and containing bodies of anorthosite, gabbroic anorthosite, gabbro, diorite, syenite, granodiorite and granite. All of these rocks are intruded by late syntectonic Proterozoic granites of the Hiltaba Suite and dykes of the Wiltabbie Volcanics. Known mineralisation includes the lodes of the Malbooma gold mine, which are located on a major northeast/south-west trending fault within the anorthosite complex. Anorthosites are essentially pure or nearly pure plagioclase-rich rocks having minor facies containing larger proportions of mafic silicates, Fe-Ti oxides and apatite. Anorthosites are relatively rare in Australia, but they host major mineral deposits worldwide. The principal target within EL 3438 is possible economic occurrences of Tertiary roll-front style secondary uranium mineralisation that may have formed within the upper reaches of the Kingoonya Palaeochannel System, proximal to uraniferous granite bodies. Potential for finding possible economic base metal or gold mineralisation associated with basement igneous bodies and structural features is also recognised. Initial exploration done by UraniumSA entailed the acquisition during May 2007 of part of a regional reconnaissance multi-licence helicopter-borne EM survey. Within EL 3438, 205 line km of AEM, magnetic and DEM data were acquired along north-south flight lines spaced 2 km apart, using a 35 m sensor mean terrain clearance, to create a first-pass interpretative map of the geography of the palaeochannel floodplains. During July-August 2007, an aircore drilling campaign of 83 vertical holes for a total penetration of 3291 m was conducted by the licensee. The drilling was designed to confirm the position of palaeochannel boundaries, and to establish the nature of the channel fill strata. Drillholes were sited primarily on the sides of station tracks where they crossed over parts of the interpreted palaeochannel system. Drilling started in the south-central area, where an extension of the Ealbara Palaeochannel was thought to exist. However, palaeochannel sediments were not found there to any degree; instead, only thin (to 10 m) transported lacustrine clays and sands appeared to have been deposited on top of weathered bedrock in a structural setting controlled by regional orthogonal structures. By contrast, in the north-eastern part of the tenement a considerable sized Tertiary basin was revealed, which appears to have an east-west orientation, as the airborne electromagnetic data had implied. The depth to basement on occasion was found to be more than 120 m, this being the utilised depth capacity of the aircore drilling rig available to UraniumSA. Two drillholes reported multiple encouraging 1-metre drill cuttings sample uranium assay values of greater than 10 ppm - these were MKAC060 (max. 58.9 ppm U) and MKAC058 (max. 44 ppm U). Both holes are located on opposite sides of the palaeochannel system, which thereabouts is some 4.5 km wide. The uranium-rich intervals of interest lie at different points in the stratigraphic profile. In hole MKAC058 the gamma ray log spike appears at the base of the transported material set on top of basement, below 52 m depth. These intercepts are encouraging, because they imply that uranium mineralisation of two different styles is present in the system. This area has subsequently been named the Bradman prospect. During September 2008, UraniumSA began a rotary mud drilling campaign to appraise the uranium mineralisation at the Bradman prospect. Unfortunately, only 1 hole for 34 m could be achieved due to drill rig mechanical failure, and shortly afterwards, because of the onset of an extremely fierce dust storm, the rest of the planned drilling programme was postponed and the rig and drilling crew were released from contract. No useful geological interpretation could be made from the results that were gained by drilling and wireline geophysically logging this one incomplete hole (MKM001). It is expected that the target Tertiary palaeodrainage basin will be further explored by resuming the rotary drilling campaign sometime during 2009. No work was done during licence Years 4 through 7. During licence Year 8, UraniumSA collected soil (585 samples scanned) and rock chip (213 samples scanned) geochemical data in the field using portable XRF spectrochemical analysis equipment. During licence Year 9, UraniumSA sampled stored drill cores in the DSD Core Library, assaying 7 selected core samples, and conducting magnetic mineral separation and resultant magnetic concentrate grain size distribution sieve analysis tests on 1 sample of drill cuttings obtained from the depth interval 36-40 m in historic drillhole MKRB274. No further work was done during licence Years 10 through 13, before a decision was made to fully surrender tenure.
More +