A sparsely drill-tested area centred about 10 km west of Lake Gilles is being explored for a variety of buried, possibly economic basement-hosted polymetallic mineralisation occurrences, including deposits of Menninnie Dam style Pb-Zn-Ag (Cu-Au),...
A sparsely drill-tested area centred about 10 km west of Lake Gilles is being explored for a variety of buried, possibly economic basement-hosted polymetallic mineralisation occurrences, including deposits of Menninnie Dam style Pb-Zn-Ag (Cu-Au), primary epigenetic unconformity-related uranium, and/or Tertiary palaeochannel roll-front type sedimentary uranium, and Middleback Range type iron ores (both haematite and magnetite). An initial program of near-surface regional calcrete sampling (collected on a 500 m spaced grid – shovel and crowbar) was undertaken to determine if calcrete was a suitable exploration medium in the licence area. Lincoln Minerals’ pathfinder suite of elements assayed for included Ag, As, Au, Bi, Ca, Co, Cu, Fe, Mg, Mo, Ni, Pb, Th, U and Zn. The calcrete analyses yielded several above background anomalies in some of these elements, in particular ranging up to 180 ppb Au and 17 ppm U. A second pass of calcrete sampling was then performed with a closer spacing (100 m spaced grid) around the highest Au and U values. This infill sampling again showed some anomalous values of Au (generally around 60 ppb) and U (around 5 ppm), although these results did not replicate the very high gold levels originally detected. In all, 599 calcrete samples were assayed. During October 2007, to test the above-mentioned calcrete gold and uranium anomalies, a total of 32 inclined aircore/slimline RC drillholes were completed by Lincoln Minerals for a total penetration of 2832 m. Two zones of significant bedrock uranium mineralisation were defined, associated with massive sulfides or sulfide-rich gneisses. No gold values above background were encountered in the bedrock, suggesting that locally there is only a superficial gold enrichment in calcrete which relates to a distal source. Hole WCAC004 intersected 72 m of sulfide-rich gneiss averaging 55 ppm U from below 36 m depth downhole, including 4 m @ 260 U from 52 m, with accompanying anomalous base metal concentrations of up to 0.07% (Zn+Pb+Ni+Cu+Co). Hole WCAC024, located 1.5 km east of WCAC004, intersected similar uranium mineralisation, including 4 m @ 522 ppm U from 72 m. The average depth of drilling in this campaign was 100 m. During licence Year 2, in separate drilling campaigns carried out in July and September 2008, Lincoln Minerals completed 8 inclined RC holes for 555 m and 45 inclined aircore holes for 4240.5 m, mainly to follow-up the Jungle Dam prospect uranium discovery. That work comprised infill drilling along the original drill traverse, plus two new drill traverses set out at ~100 m distance to the north and south. This spread of holes identified a NNE-trending zone of mineralisation which appears to be a supergene blanket developed over uraniferous polymetallic quartz veins present in graphitic gneiss. The primary veining is associated with sulfide alteration. The best intercept made in the supergene interval was 8 m @ 0.02% U in hole WCAC042. A trial plant biogeochemical survey was performed at Jungle Dam prospect during February 2008, to ascertain whether the method was a viable exploration tool for use locally. Several species were selected: (1) for their wide distribution over the prospect and (2) for the depth of their root-systems. Leaves of bluebush (Cratystylis Conocephala, Maireana Sedifolia), mulga (Acacia Aneura) or mallee (Eucalyptus Gracilis, Eucalyptus Socialis or Eucalyptus Oleosa), as well as twigs and barks of mulga, were sampled. The samples were assayed for a large suite of elements found in the known supergene mineralisation, as well as potential pathfinder elements. The survey's results were provisional but promising. Six samples of mallee showed a high uranium content compared to background values. The highest uranium concentrations were found in the vicinity of the mineralisation defined by drilling. Bluebush and mulga gave equivocal results. It was concluded that more such work would be needed to establish the validity of this type of qualitative geochemical indicator for exploration use in the region. Additionally, in the north of the tenement, Lincoln Minerals performed part of its Year 2 drilling to investigate the possible presence of palaeochannel uranium mineralisation, that had been suggested by the interpretation of results from previous calcrete sampling, radiometric anomalism and remnant topographical considerations. 8 RC holes and 6 aircore holes were drilled along a single traverse, but no such mineralisation was encountered. Thin and polished section petrographic studies made on selected rock chips samples collected during the 2008 Jungle Dam drilling programme showed that the basement is gneissic, rather than granitic, and that quartz veins and associated hydrothermal alteration are commonly present. Subsequently, a series of laboratory mineralogical and leaching tests were conducted on mineralised drill cuttings bulk samples in order to understand the extractive properties of the valuable metals likely to occur any associated orebody. Samples from holes WCAC042 (depth 46 m) and WCRC008 (depth 56 m) were chosen to undergo quantitative mineralogical analysis by XRD and QEMSCAN. This work was done by AMDEL Limited at their laboratory in Adelaide. The results obtained from XRD analysis did not reveal which minerals carried the uranium. QEMSCAN analysis, however, indicated that the uranium is carried in francoisite-(Ce) having the chemical formula (Nd,Y,Sm,Ce)(UO2)3(PO4)2O(OH)·6(H2O). Francoisite is known to be spatially closely associated with uraninite and coffinite (Janeczek and Ewing, 1996, Hidaka et al., 2004). A composite of the best-mineralised samples obtained from a 5 m thick depth interval in drillhole WCAC042 were provided to AMDEL in February 2009 to have the laboratory perform a leaching test. Carbonate leach and acid leach tests were conducted at 70°C for a duration of 12 hours, on rock material ground to minus 1.7 mm in particle size. Residues and solutions were taken every hour for assay. It was found that carbonate leaching recovered 22% of the uranium present in the composite sample, whereas acid leaching recovered 35% of the uranium. It was suggested that the leaching results for both soluble uranium and vanadium could be improved by increasing the temperature or adding an oxidant to the acid test. Other work undertaken by Lincoln Minerals during the year consisted of further reconnaissance and geological mapping, which led to the collection of 8 stream sediment samples plus 18 rock chip samples of outcrops. The stream sediments did not show any anomalous trace metal concentrations, except for one sample containing 650 ppm Cu and 30 ppm U. This sample came from a previously detected geochemically anomalous zone where uranium mineralisation was discovered in 2007. The sampled outcrops mainly consist of quartzite or vein quartz. Several gossanous outcrops also occur. Hydrothermal breccias also crop out in the north-east of the tenement. One sample of gossan contained 0.26% Cu, 8.3 ppm Ag, and 40 ppb Au. Farminee IronClad Mining commenced exploration on EL 3690 in March 2008, by contributing to the cost of flying a low level airborne magnetic and radiometric survey of 1648.25 line km, which mainly targeted an extension of the Hercules iron ore prospect that is concealed below alluvial cover. This prospect had already been defined as a 7 km long regional magnetic anomaly, of which 500 m strike length lies within EL 3690, while the major portion lies within Trafford Resources' adjoining EL 3981 to the north-west. The new airborne geophysical data was acquired along east-west aligned flight lines spaced 100 m apart, using a magnetometer sensor height of 60 m above the land surface. The survey data revealed more accurately the extent of high magnetisation features which clearly arise from the Palaeoproterozoic banded iron formation (BIF) strata of the Hercules prospect. In addition, strong north-west trending magnetic anomalies denoted that Gairdner Suite dolerite dykes are also present. The aerial radiometric data showed a major east–west trending uranium channel anomaly in the northern part of the tenement. This coincides with several uranium anomalies in calcrete detected earlier by Lincoln Minerals. However, the drilling done so far had not intersected any uranium mineralisation in this part of the tenement. Before the airborne survey was flown, IronClad conducted a detailed ground gravity survey across the western part of the licence area during January-February 2008, when 1214 stations were read on a 250 m x 250 m grid. The resulting gravity data revealed bedrock density anomalies which are not associated with magnetisation, and IronClad interpreted these to possibly be representing bodies of haematite. During the period June to September 2008, IronClad drilled 10 inclined RC holes for 1008 m along two east-west traverses to test the Hercules South portion of the Hercules prospect gravity anomaly complex. Downhole wireline geophysical logging was undertaken on 4 of the holes, collecting gyroscopic position-with-depth, magnetic susceptibility, density, gamma ray, caliper, and resistivity log data. Differential GPS methods were used to very accurately measure the holes' surface collar positions. The drilling intersected BIF ironstone strata containing metamorphic haematite/goethite or magnetite - rich mineralised layers, as well as some overlying eroded detrital haematitic material. The bedrock ironstones are surrounded by Warrow Quartzite, and are distributed around a major northeastwards-overturned synclinal fold that has been subjected to sub-folding. During licence Year 3, Lincoln Minerals collected an additional 234 biogeochemical samples of mulga and mallee leaves, as well as twigs and barks of mulga, from the south-western corner of the licence area. The plant material assay results obtained from this wider area appeared promising, with samples of the above vegetation, growing in the geologically extrapolated direct prolongation of the known Jungle Dam main mineralised zone, having highly anomalous uranium content. In the same twelve-month period, partner IronClad Mining did not undertake any further iron ore exploration, and therefore did not spend the required amount of money before December 2009 that would secure its initial earn-in rights. [ Forward-looking note: on **** 2010, the company chose to withdraw from the participation Heads of Agreement, and in consequence, Lincoln Minerals regained the full rights to iron ore that might exist on EL 3690. ]