During the first year of renewed tenure under EL 3445, the work done consisted of performing diamond and RC drilling programmes which were partly funded by PIRSA's PACE Initiative as Theme 2, Year 2 and 3 approved Drilling Collaboration Projects....
During the first year of renewed tenure under EL 3445, the work done consisted of performing diamond and RC drilling programmes which were partly funded by PIRSA's PACE Initiative as Theme 2, Year 2 and 3 approved Drilling Collaboration Projects. The subsidised programmes included the collection and analysis costs for 1570 geochemical downhole samples as well as for 24 petrological samples and 1 groundwater sample. A programme of 5 inclined diamond drillholes for a total penetration of 1740.6 m was completed over the period October-November 2005, as part of PACE Project DPY2-35, to follow up anomalous PGE values intersected in drillhole KDRC001 in late 2004. Hole KDD003 was designed to establish the dip of the mineralised zone, by intersecting it at a much deeper position than the discovery hole had. Holes KDD001 and KDD002 were drilled to the north of this initial hole in order to test for potential higher grade zones nearer to the gravity anomaly. Holes KDD004 and KDD005 were drilled in an attempt to intersect the mineralised zone along strike. Disappointingly, the basement assay results for most of these appraisal holes were low, with the exception of those for hole KDD003, which intersected 22 m @ 0.91 ppm PGE (Pd+Pt+Au) from below 148 m depth, including 2 m @ 1.94 ppm PGE from 151 m, and 6 m @ 1.15 ppm PGE from 160 m. The holes penetrated a sequence of felsic and mafic gneisses / orthogneisses and quartz-plagioclase-garnet gneisses that contain patchy āmafic skarnā alteration and pyrrhotite±PGE mineralisation in KDD003 and weaker such alteration in KDD002. The shallower RC drilling campaign, of 5 vertical and inclined holes for 658 m, was conducted during August-September 2006 as part of two separate PACE Drilling Collaboration Projects, DPY3-28 and DPY3-29, targeting possible economic IOCG and uranium mineralisation respectively. Two RC holes were drilled to test subsidiary high intensity ground magnetic anomalies at the Snaefell prospect, one hole was sited to test a complex, southwards dipping high amplitude IP anomaly at Anomaly 9, and the remaining two investigated gravity lows that were thought to arise from shallow sediment-filled troughs which could be prospective for uranium mineralisation. No anomalous uranium was detected. However, MWRC012 drilled at Anomaly 9 returned anomalous platinum and palladium, in the ratio 4:1, with a best assay result of 4 m @ 0.74 g/t Pd+Pt+Au obtained from below 56 m depth in composited 1 metre drill cuttings of magnetite banded mafic gneiss, in part grading to massive magnetite. Minor chalcopyrite and pyrite was observed associated with the massive magnetite. Drilling of basement magnetite-rich gneiss at Snaefell prospect revealed a broad interval of elevated iron content, but no IOCG style sulphides, and only background geochemical levels of other elements. Hole MWRC010 revealed an intercept of 92 m @ 29.6% Fe over the depth interval 40 to 132 m (EOH). Hole MWRC011 encountered similar basement rocks, returning 80 m @ 32.4% Fe from 40 m to 120 m (EOH). [The Snaefell aeromagnetic anomaly is regarded by Goldstream as an important iron ore exploration target within the Mount Woods region, being second only to the Cairn Hill anomaly in its total magnetic intensity (peaking at 22,000 nT)]. Drilling of inferred palaeochannel sediments deposited adjacent to a south-westwards trending basement shear zone in the NE corner of EL 3445 did not detect any uranium in the depth interval 35-62 m of hole MWRC009 where sands and gravel are present, as the results of drill cuttings scintillometer scans and assays were at very low levels. Some weakly anomalous gold is present within underlying claystones (32 ppb Au from 96-100 m and 30 ppb from 128-132 m). To try to assess the regional uranium potential in the shear zone, a single groundwater sample was collected from 5 m below the standing water table. Immediately upon collection, field measurements were made of properties that may change rapidly after groundwater sample collection, viz. conductivity (as an indication of salinity), pH, Eh, reduced Fe (Fe2+ species) and temperature. Also, the major elements that might be dissolved in the groundwater were analysed using ICP-OES (Al, Ca, K, Mg, Na, P, S, Si) and ICP-MS (Li, Be, B, Sc, Ti, V, Cr, Mn, Fe, Co, N, Cu, Zn, Ga, Ge, As, Br, Se, Rb, Sr, Y, Zr, Nb, Mo, Ru, Ru, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, La, Ce, Pr, Nd, Eu, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Pt, Au, Hg, Tl, Pb, Bi, Th, U) at Actlabs Pacific Pty Ltd in Perth. Analyses of Cl and F were made using selective ion electrodes and total carbonate by acid titration. No anomalous geochemical signatures were found which would suggest proximity to any uranium mineralisation. Detailed geological and petrographical studies were made of the KDD003 and KDD002 drill cores by specialist consultants, who reported to Goldstream that, geologically, the drillholes had intersected a sequence of high-grade felsic and mafic gneisses, and quartz-plagioclase-garnet±biotite gneisses. The mafic component appeared to dominate in a third step-out hole, KDD004, which is located ~100 m to the east of the above two mineralised drillholes, and a suggestion was made that this rock type's petrophysical nature may influence the large gravity ridge that runs through the central part of the Kangaroo Dam tenement. Hole KDD003 intersected a sequence of felsic gneiss in its upper portion and an extensive zone of quartz-garnet gneisses with distinctive pink-purple garnets and white quartz banding.The best zone of mineralisation, that occurs in this hole, is located on and just below the transition between the two gneissic sequences. It lies within a dark-green to grey quartz-amphibole-pyroxene, ±plagioclase±garnet±biotite, fine-grained mafic lithology that may have originally been a sediment or intermediate volcanic rock. Petrographic examination of the KDD003 core concluded that the nature of the Pd-rich pyrrhotite vein mineralised zone is puzzling, as only part of this zone, from 143-160 m depth, is rich in Mg and thus possibly related to mafic magmatic rocks. The rest of the zone, extending from 160 to 171 m depth, seemed to represent Pd-rich pelites with moderate sulphide contents. Further evidence, seen in the presence of sphalerite at 145.78 m and molybdenite at 152.5 m, suggested that the veins are hydrothermal sulphide. But it was not clear why the Pd/Pt ratios are so high, or why there is such a poor correlation between Pd and S, although the most Pd-rich samples are also rich in S. Samples with > 0.5 ppm Pd have >1.8% S, but Pd-poor samples have as much as 4% S. During the seventh year of tenure, the licensee's activities included surveying and site preparation, rotary mud drilling, water bore drilling, rehabilitation activities and the completion of a detailed airborne helimagnetic survey. 7 vertical rotary mud holes for 877 m were completed during March-April 2007 in a continuation of the sedimentary uranium search. The first 4 of the holes were drilled to test palaeochannel sediment packages known to exist to the west and north-west of Cairn Hill, with the dual purpose of testing their groundwater supply potential for contributing to planned mining operations, besides determining the suitability of the strata to host sandstone roll front type uranium deposits. All of these holes intersected sands and gravels of the Cadna-Owie Formation, followed by thick sequences of clays, sands, claystones and mudstones of unknown associations that persisted down to the end of each hole. No anomalous uranium assay values or geophysical log signatures indicative of proximal uranium mineralisation were detected. However, the drilling confirmed the presence of gravity-interpreted palaeochannels containing significantly thick sediment packages. The other 3 rotary mud holes, drilled adjacent to the 4 uranium exploratory holes, were designed as dedicated groundwater monitoring bores that would form part of a regional groundwater monitoring programme, contributing baseline data to the Cairn Hill Mining Project groundwater supply investigation being conducted by Parsons Brinckerhoff. During mid-May 2007, IMX Resources contracted the acquisition of a 383.2 line km helimag airborne survey over the Kangaroo Dam prospect / Anomaly 9 area, read along 53 NE-SW orientated flight lines spaced 100 m apart, using a 25 m mean sensor height above the ground surface. This survey was intended to better elucidate basement structure and help define new IOCG drilling targets. During licence Year 8, the only field work carried out was the drilling of 2 inclined RC holes for 320 m during January-March 2008 to further test the IOCG potential of the Anomaly 9 PGE occurrence. The anomalous PGE values intersected there on the cover-basement unconformity in previous hole MWRC012 were not repeated in the follow-up holes, so it was decided that the source of the PGE anomaly does not lie to the south of MWRC012. Hole MWRC015 intersected 58 m of cover sands and clays, before basement with a 1 m thick ferricrete cap was reached at 59 m. Its lithology consists of magnetite-rich amphibolite, plus a narrow zone of magnetite-rich gneiss from 97 to 102 m. Drill cuttings assay results were uniformly low. The uppermost basement zone from 59 to 110 m averages 19.36% Fe, while values for other elements are at background levels only. The maximum values of Cu (133 ppm) and P (about 1%) are associated with the most iron-rich section. Hole MWRC016 reached basement at 54-55 m, beneath a cover sequence of clay and sand. The basement consists of a mixture of amphibolite and mafic gneisses, with varying proportions of fine-grained disseminated magnetite or magnetite-rich bands. Drill cuttings assay values were only low, with a section from 112 to 146 m averaging 16.46% Fe. The first sample taken at the top of the basement contained the highest values of Co (100 ppm), Ni (95 ppm), and Pb (75 ppm). The downhole wireline gamma ray logs that were run showed no significant radiometric anomalies. Peak values recorded in both holes are located at the cover-basement unconformity, with readings of around 300 cps. Magnetic susceptibility readings collected for both holes show anomalous values of between 0.04 to 0.06 SI for MWRC015 and 0.05 to 0.1 SI for MWRC016, that are considered sufficient to explain the targeted magnetic anomalies. Consultant geologist Finn Barrett was engaged late in 2007 by IMX Resources to investigate the unusual fact that, in the Kangaroo Dam area, several of the holes drilled by Anglo and IMX have discovered strong palladium anomalies, but little or no associated platinum or gold. His initial finding, upon inspecting the relevant rock geochemical data, made the emphasis that basic and ultrabasic rocks usually have such simple mineral compositions that stratigraphic geochemical variations are normally predictable. In contrast, the rocks at Kangaroo Dam vary considerably and therefore are probably not meta-basites. The compositional variations found in holes ARC15-28, KDD1-5 and KDRC1-2 are erratic, with poor correlations between major and trace elements. The ānoisyā geochemical stratigraphy of the Pd-anomalous holes presumably reflects lithological variation and possible alteration along fractures and/or faults. Barrett noted that the strong negative correlation between magnetite and sulphide abundances, and the fact that Pd occurs in the S-enriched zones on the margin to magnetite-rich rocks, suggest that Pd concentrations are not magmatic but are related to later regional alteration events, possibly involving saline, oxidised fluid (that can transport Pd but not Au or Pt) interacting with reduced, sulfide-bearing rocks possibly related to an earlier alteration episode. Evidence he cited for proposing alteration due to the presence of oxidizing saline fluids includes: ⢠minor to moderate enrichment of La and U associated with Pd; ⢠the probable presence of sodic alteration; ⢠the presence of high Al values in certain units (which suggests that rocks logged as quartzites are more likely to be albitites); and ⢠the widespread occurrence of scapolite. As the high Pd values are located in only weakly magnetic rocks, he believed that the drilling of magnetic highs is not a recommended exploration strategy. Targeting the margins of magnetic highs may be more promising. Barrett suggested that tracking pathfinder elements might be a useful tool in recognizing both (i) oxidized, highly magnetic rocks close to Pd-mineralised contacts, and (ii) sulphide-bearing skarns. So he recommended that a wider suite of elements be analysed in the geochemically very anomalous hole KDD003, where every third sample from the depth interval 50-200 m should be analysed for the extra elements Ag, Al, Ba, Bi, Ce, K, La, Mo, Na, Sc, Se, Sn, Te, Th and U. If a reliable set of pathfinder elements could be defined for the Mount Woods Inlier, he expected that sampling of fences of RAB holes drilled across the margins of its magnetic highs could be a useful exploration approach. He also recommended that downhole EM surveying be trialled in KDD003 as a means of directly detecting sulphides, which may carry economic copper as well as PGE. During the ninth year of tenure, the licensee's main focus was to begin evaluating the Snaefell prospect as a potential source of magnetite iron ore that could be used to augment the output planned for the Cairn Hill Mining Project. Consequently 14 reconnaissance RC holes (2 abandoned) for 2290 m were drilled there, out of the annual total of 27 exploratory RC holes for 4303 m that were completed on EL 3445. The drilling results obtained from the western part of the long and curved Snaefell antiform showed that the magnetite occurring within its total length could probably develop into a large resource, based on further appraisal drilling. A currently inferred resource estimate of between 270 and 400 Mt @ 25-35% Fe was announced by IMX to the Australian Stock Exchange on 12/11/2009. Preliminary knowledge obtained about the resource geology and mineralisation was summarised by consultant Ian Garsed as follows: ⢠The host sequence is a tightly folded unit that has been truncated by a fault or shear running parallel to the trend of the unit. ⢠The prospect gravity and magnetic anomalies, as now measured and modelled in detail, are coincident. ⢠Drilling to date has tested the western end of the magnetic and gravity anomalies; additional drilling is recommended in the central portion and at their eastern end. ⢠The IP anomaly originally defined by WMC in 1997 is a broad feature that is probably due to the magnetite mineralisation. It has already been tested by the single hole DD87LR01 drilled previously by CRAE. ⢠The dip of the mineralisation is uncertain from the drilling reviewed here. The interpretation of tight folding from the magnetics, and seen in the DD87LR01 drill core, shows that data to be gathered from wider drill traverses, and some oriented core, will be necessary to resolve same. The next area of focus for IMX in Year 9 was the historic Aquila prospect located south of Snaefell, exhibiting semi-coincident aero magnetic and gravity (2 mGal) anomalies which lie near the intersection of major regional ENE- and WNW-trending structures. In 1997 WMC had completed a (phase-domain) IP traverse there that revealed a moderate but distinct chargeability response of ~20 mrad which never got to be drill-tested. Early in 2009, IMX retained Zonge Engineering to re-model the WMC IP data and to undertake a time-domain, 100 m spaced, dipole-dipole IP survey over the Black Hills prospect on its adjoining Mt Woods EL 3518, that also included one N-S, 2.7 km long IP traverse run across the Aquila prospect; this new line obtained a comparable strength chargeability anomaly of ~13 msec, thus defining a possible buried sulphide drill target. 4 RC holes (1 abandoned) for 784 m were drilled during January and August 2009 to test the IP and magnetic anomalies, but difficult ground conditions hampered the drilling. Hole MWRC040 was drilled into the magnetic anomaly, however it is likely that it missed the main part. Hole MWRC069 tested the IP anomaly, but here again, it appears to have dipped too low and just missed the target zone. During July-August 2009, IMX contracted Hugh Patterson to acquire detailed gravity survey coverage over four priority aeromagnetic anomalies, Aquila, Bumblebee, KD20 and KD23, to assist with the iron ore and IOCG search. The gravity lines were spaced either 100 m or 200 m apart, with stations read at 50 m intervals, for a total of 879 readings that infilled Anglo's earlier semi-regional coverage. The new gravity data were modelled and interpreted by consultant Kath Wilkinson to complement her earlier similar treatment of the aeromagnetic data. Bumblebee prospect (formerly Anomaly MW45) is a linear, high-amplitude magnetic anomaly located adjacent to the western margin of the Penrhyn pluton. It is about 3 km to the south-east of the Aquila prospect, near the southern bounding structure of the Mount Woods Inlier. Holes MWRC071 and 072 were drilled here to test the peak of a 1 mgal gravity anomaly and associated magnetic anomaly. As modelled, the strong aeromagnetic anomaly at KD23 prospect has two separate sources: a short E-W trending linear, and a circular anomaly to the south that looks to be a pipe-like, possible kimberlite intrusion. Holes MWRC037 and MWRC038 tested the margin of the latter, encountering weak Cu-Au mineralisation in the mixed, magnetite gneiss-mafic gneiss and in part carbonate altered bedrock beneath 50 m of cover. The magnetite-rich bedrock in both holes carries 30-38% Fe. MWRC038 also has some narrow intervals with up to 5% sulphides, yielding highest assay results of 14 ppb Au, 923 ppm Cu, 336 ppm Zn, 117 ppm Ni and 69 ppm Co. Holes MWRC073 and MWRC074 were drilled to test the magnetic anomaly at Fitzgerald Dam, where there is a coincident 1.5 mGal gravity high. The magnetic feature was modelled as being caused by SE-dipping bodies of moderate susceptibility. Magnetite-rich gneisses were intersected in MWRC073 (136 m @ 30.32% Fe, including 2 m @ 38.4% Fe from 51 m). The bottomhole drill cuttings sample taken at 204ā244 m depth contained chips of a distinctive pale diopside-speckled calc-silicate/skarn. The second hole, MWRC074, was abandoned at 168 m. Holes MWRC063 - MWRC067 were drilled to test a possible dilational zone between two dip-convergent magnetic plates forming the end of a magnetic ridge extending westwards from Kangaroo Dam prospect. No evidence of mineralisation was found. In the east of the licence area, three of a series of magnetic and gravity anomalies which appear prominent within a NE-trending magnetic horizon bordering the eastern margin of the Black Hills Gabbro were tested by RC drilling. 3 holes were drilled at anomaly MW75, and 5 holes each at anomalies MW78 and MW80. The exploration targets were magnetite-rich sedimentary gneisses located along strike to the south-east from the Cairn Hill deposit, in places that are offset by a number of ENE and NW striking faults. The strata were expected to dip steeply towards the south-east. Only sub-economic iron mineralisation was encountered, grading at around 20-25% Fe. At anomaly MW78, weak copper and chromium values were recorded from hole MWRC046 within mafic gneiss in proximity to a graphitic shear zone. During the tenth licence year, work undertaken by IMX included RC drilling at its Snaefell magnetite prospect, and rehabilitation of past drillsites. Oz Minerals Limited (OZL) acquired an ~2500 line km Falcon airborne gravity gradiometer survey across the whole EL, and a 6.8 line km, 50 m station spacing 3 traverse time domain, dipole-dipole IP survey over its Shadwell target located immediately west of the Aquila prospect. As part of IMX's iron ore exploration program, 5 inclined RC holes for 1150 m were completed at Snaefell during October-November 2010 in the fold structure thickened 'core' area, to the east and west of previous drillholes. This drilling showed that the iron mineralisation is continuous, by successfully encountering several wide zones between 72 and 103 m depth carrying 27-33% Fe as magnetite and subordinate specular haematite. The host is a tightly folded gneissic unit that may represent a highly metamorphosed, granulite facies iron formation with interbedded carbonate units. The mineralised sequence appears to be truncated by a fault running parallel to the E-W trend of the prospect. Also during November-December 2010, IMX drilled one rotary mud precollared diamond hole to 394.6 m depth, to obtain drill core samples of the Snaefell iron mineralisation to submit for preliminary metallurgical tests and detailed petrographic examination. The orientation of the iron-mineralised sequence appears to be parallel to the main foliation of the host units, dipping steeply to the north. On the north side of the prospect, the iron-mineralised sequence appears to have been truncated by the north-dipping fault or shear structure. Petrology observations made from 28 drill core samples of hole SFD001 indicate that the iron ore formation results from 2 metamorphic events: - a 1st metamorphic event (progressing to greenschist facies?) Semi-pelitic sediments with some initial Fe were altered by greenschist facies metamorphism to gneiss and schist, with quartz, Fe-rich biotite, magnetite ± K-feldspar ± plagioclase ± apatite; the presence of scapolite hints at precursor evaporite units. - a 2nd metamorphic event (higher grade: upper amphiboliteāgranulite facies), possibly with a metasomatic event. During the metamorphism and oxidation of the above-described assemblage, Fe-rich biotite (annite) became magnetite + K feldspar + H2O, thereby effectively upgrading any primary magnetite. The presence of orthopyroxene in a sample indicates metamorphism continued (prograde) to granulite facies before a late retrograde stage ā perhaps during a metasomatic event that saw potassic alteration and the formation of the pervasive coarse-grained K feldspars. Amdel's laboratory metallurgical studies involving Davis Tube Recovery initial testing showed that magnetite gneiss running 34ā40% Fe could be upgraded to 68ā70% Fe. Detailed mineralogical logging of the SFD001 diamond drill hole confirmed the presence of good magnetite mineralisation but also the occurrence of mixed iron ore varieties: ⢠earthy hematite + magnetite in the upper weathered zone to 114 m, ⢠earthy hematite + specular hematite + magnetite, and ⢠specular hematite + magnetite. The identification of the mixed iron ore mineralisation, in addition to magnetite-only mineralisation, prompted the conduct by Amdel of further beneficiation testwork on the mixed ore varieties, which yielded encouraging results. Wet LIMS magnetic separation at a P80 of 150 microns could produce a 66% Fe magnetite concentrate. As with Cairn Hill, the Snaefell magnetite appears to be relatively coarse-grained, which will confer lower capital and operating costs on any development project. During 2010, OZL undertook additional diamond drilling (as diamond 'tails' to existing RC holes) in order to better understand the IOCG potential of certain better-ranked prospects. At Aquila, hole MWRC070 was extended with a diamond tail (MWRCD070) cut from 270.3 to 330.5 m depth in an attempt to effectively test the modelled sulphide source of the anomalous IP response. The drill core comprises strongly-foliated mafic gneiss (?after gabbro) with up to 2% fine-grained disseminated pyrite in places, of a quantity thought sufficient to explain the geophysical response. At Fitzgerald Dam, hole MWRC074 was extended with a diamond tail (MWRCD074) cut from 168.3 to 269.4 m depth to try to locate the down-dip extensions of the magnetite-rich rocks intersected in hole MWRC073. The MWRCD074 drill core comprises pyroxene monzonite gneiss and bands of meta-sedimentary rocks, notably carbonate breccias/marble, interbanded with <5% magnetite-bearing meta-siltstones, and pale diopside speckled calc-silicate/skarn, but these bands grade at nothing like the + 30% Fe magnetite-rich intercept of MWRC073. The carbonates carry occasional patches of disseminated pyrrhotite and rare chalcopyrite. IMX thought that the occasional bands of magnetite-bearing gneiss which are present in the drill core, e.g. at 198ā204 m and at 257ā272 m, are possibly similar to the banded units intersected in the bottom half of MWRC073, which would imply that the units do not dip southwards as modelled, but are vertical or dip steeply northwards. The Coober Pedy Falcon airborne gravity gradiometer survey was completed by Fugro for OZL and IMX during the period April-June 2010 over most of the Mount Woods Project area, and included the entire Kangaroo Dam tenement, where the AGG data were acquired along flight lines 200 m apart, using a mean sensor height of 80 m above the ground surface. [The survey data were being processed at the end of the 2009-2010 reporting period, and a relevant subset will be presented in the tenement's next annual report].