The Peterlumbo Project area covers an area of 583 km2 and is situated 60 km north-west of Kimba, immediately south of the Gawler Ranges on the northern Eyre Peninsula. The initial primary exploration target within the tenement was the covered...
The Peterlumbo Project area covers an area of 583 km2 and is situated 60 km north-west of Kimba, immediately south of the Gawler Ranges on the northern Eyre Peninsula. The initial primary exploration target within the tenement was the covered source to the 6 mGal amplitude “Victory” gravity anomaly. This anomaly lies at the intersection of major north-east and north-west trending faults interpreted from other geophysical data. The north-east trending fault structure hosts copper, lead-zinc, and gold mineralisation, such as at the Olympic Hill prospect, where anomalous gold and lead were found in haematite veins, and at the Mawson prospect, where drilling intersected 29 m @ 0.9% Cu. The anomaly had previously been investigated by M.I.M. Exploration Pty Ltd (MIM), with a detailed gravity survey and an IP survey, which led them to drill on the shallow IP responses in the structures on either side of the interpreted source of the gravity anomaly. The prospect has gravity, geological and geochemical attributes that demonstrated to Southern Gold Ltd the potential for IOCG deposits, both within the immediate area and regionally along the southern margin of the Gawler Range Volcanics (GRV). Extending the proposed metallogenic models for the highly mineralised Menninnie Dam - Weednanna system, the project area appeared to Southern Gold to lie in a position that is optimal for occurrences of subvolcanic Hiltaba age deposits of the IOCG style. This particular model was supported by the occurrences of haematite mineralisation in rare outcrops at Olympic Hill, 2 km south-east of the Victory target, and at Nankivel Hill 25 km to the west. During Year 1, Southern Gold undertook a review of previous exploration data and reports, in conjunction with making several field trips to verify existing mapping and the recorded presence of ironstone lag. A surface soil Mobil Metal Ion (MMI) geochemical sampling program was initiated over the Victory gravity anomaly, in the hope that it might provide better detection of any anomalism dispersed through the transported cover. During Year 2, Southern Gold continued their MMI soil program. A total of 1122 samples were collected along 16 traverses x 200 m apart spaced lines. “Modest” 2 x background anomalies were detected along a NW trend, said to be indicative of a “structurally controlled mineralised corridor”. Ground gravity and MIMDAS survey data previously collected by MIM were remodelled and reviewed to try to support the MMI soil result and thereby refine a drilling target. In late 2005, four RAB and HQ/NQ diamond tailed holes for a total of 1109 m were drilled across the gravity feature as part of the SA Government’s PACE Initiative Year 2 collaborative drilling approved project DPY2-25, in joint venture with Hindmarsh Resources (see ENV 11169). This drilling intersected a variably altered and sulphidic mafic intrusive rock in contact with graphitic and sulphidic metasediments which contained random sulphide veins, quartz-garnet veins, and zones of pervasive sericite-chlorite alteration. The gravity feature tested by holes VP05-001, 002 and 004 appeared to be caused by a thick succession of variably deformed basalts. Rock chip geochemical sampling (15) was undertaken across the tenement targeting specific areas (uranium anomalies, and proximal to past drillholes). Nine drill chip and core samples were described petrologically. Grant licensee Southern Gold’s newly spun-off subsidiary Southern Uranium Ltd, and suitor Mega Hindmarsh Pty Ltd, entered into a progressive JV agreement in April 2005 whereby, initially, Mega Hindmarsh was entitled to earn a 25% interest in the Peterlumbo Hill Project by spending $250,000 over three years, and subsequently could increase its share of the project to 35% by further spending. During Year 3, Peterlumbo Project work was reported on by Southern Uranium, who between November 2005 and February 2006 conducted a multi-licence gravity survey totalling 1406 stations, with 355 stations read across selected parts of EL 3158. The new gravity data were interpreted by AsIs International, who calculated the possible depth and density characteristics for the sources of anomalies at Nankivel Hill. During licence Year 4, exploration reporting was done by joint venturer Mega Hindmarsh (Hindmarsh). Its exploration focus was on previously identified gravity anomalies (G1 - G3) as potential IOCG-U Carapateena-style deposits. Hindmarsh undertook 2 geophysical surveys during the reporting period. A handheld magnetometer survey covering 31.14-line km was conducted over the G1 and G2 anomalies. The aim was to define a potential redox interface between the magnetite and haematite. A gravity survey consisting of 314 stations was read in over the G1 - G3 gravity anomalies. Both geophysical surveys were submitted to Archer Geophysical Consulting for analysis and interpretation. The gravity survey data read over the G2 anomaly indicated a source body of elevated density (2.97 g/cc) at 230 m depth. To refine drill targets, a surface geochemical sampling program (978 soil and 8 rock chip) was conducted over the G1 and G2 anomalies, after which Hindmarsh drilled 3 RC pre-collared diamond cored holes (NQ2 x 2, & HQ/NQ2) for 553.8 m. Two of the holes were drilled into the G2 anomaly. In hole 07RCDHPL01, anomalous uranium values up to 220 ppm U occur within several narrow-cored intervals of sheared graphitic metapelites of the Paleoproterozoic Hutchison Group, although no magnetite-haematite redox front was intersected. In hole 07RCDHPL02, anomalous uranium to 180 ppm U was intersected within a 15.7 m thick pegmatite dyke; however, the G2 gravity anomaly was explained by dense meta-basalts, interbedded with metasediments of the Hutchison Group, that were intersected in this hole. The third hole, 07DHPL03, tested the “Ad” radiometric anomaly identified by previous explorers, but no uraniferous rocks were encountered. This anomaly was now attributed to a landform effect caused by the weathering of an isolated exposure of radiometrically anomalous Gawler Range Volcanics surrounded by transported regolith. During Year 5, no field work was carried out and no new technical information generated. In May 2008, Mega Hindmarsh advised Southern Uranium that they had completed the first tranche of expenditure required by the JV agreement, but now wished to stop sole funding new work in order to maintain just the earned, lesser 25% interest in the project. Therefore, Southern Uranium resumed management of EL 3158, before the tenement was re-applied for and granted as EL 4228. During Year 6, a two-phase soil geochemical sampling program was undertaken utilising partial leach analytical techniques. The first phase “regional” program saw 928 samples collected on a 500 x 500 m grid in the east and on a 1 x 1 km grid in the west over two areas identified by previous explorers as prospective. Three prospects (G1, Nankivel and Victory East) were identified as anomalous, and were infilled sampled during phase 2 (723 samples). Six rock chip samples were also collected from Nankivel and assayed. During Year 7, reporting was completed by Investigator Resources Ltd (during the 2010 company AGM, it was voted and carried through to change the name of Southern Uranium to Investigator Resources, to reflect the company’s move away from having a uranium-centric exploration focus). Following on from the previous year’s successful soil sampling program, geological mapping, and rock chip geochemical sampling (131 samples) were undertaken to investigate anomalous soil results. Many rock chip samples returned significant assay values, particularly in Ag, Pb and Zn, while several samples also contained elevated Au. Importantly, 5 rock chip samples returned Ag values >50 ppm Ag, and 10 others had >10 ppm Ag. Previous surface geology mapping conducted by Aberfoyle and MIM, and also by GSSA to prepare the YARDEA 1:250k regional geology mapsheet, had shown relatively little outcrop within the subject licence area. But Investigator’s current detailed mapping had revealed the existence of significantly more outcrop and "subcrop". Recognition of argillic alteration of volcanic rocks in outcrops that were previously mapped as quartzite and silcrete was considered a major step in advancing the project, as it is a common feature of major porphyry copper mineral systems. A detailed aeromagnetic/radiometric survey, using 100 m spaced flight lines, was flown over the western side of the tenement in August 2010, and was used to refine planned drilling. In January 2011, 66 aircore/RAB/slimline RC vertical and inclined holes for 3193 m were drilled (PLAC001-066). Investigator obtained drilling results which they considered were suggestive of an epithermal system having once existed in the area. The petrographic analysis of 2 drill chip samples from hole PLAC042 supported this interpretation by finding significant sulphide within skarn-related host dolomitic metasediments. During Year 8, further soil geochemical sampling utilising partial leach analytical methods was conducted across the tenement. Soil samples (2300) were collected from over 6 previously identified anomalies (Paris, Helen, Trojan Horse, Helen South-west, Alexander and Centurion) on 100 x 100 m grids. Several grids produced coherent multi-element anomalies, including the Paris prospect. Initial drilling took place on the Paris prospect and comprised 69 aircore holes for 4607 m on a nominal 100 m x 50 m grid (PLAC067-135). Twenty-six selected drill chip samples were submitted for petrological studies, with a further 5 samples submitted later to identify probable silver mineralisation. Native silver was observed under reflected light as inclusions within pyrite. 6 rotary percussion pre-collared diamond HQ/NQ3 cored holes for 12,339.2 m were drilled on Paris (PPDH001-006). Several significant mineralised intercepts were made, including one spectacular grade hit of 11.6 m @ 3646 g/t Ag, 2.4% Pb and 4.2% Zn (PPDH002, 63.5-75.1 m). Investigator now believed that from their recent work they had discovered a significant silver deposit, so in early 2012, 43 RC holes for 6372 m were drilled along 11 traverses on Paris (PPRC001-043). Again, many significant base metals, and gold, hits were recorded, e.g., 22 m @ 1318 g/t Ag, 2.03% Pb and 1.36% Zn (PPRC003, 73-95 m), 5 m @ 2395 g/t Ag, 0.31% Pb and 0.68% Zn (PPRC008, 101-106 m), and 10 m @ 1.71 g/t Au, including 2 m @ 6.26 g/t Au (PPRC036, 41-51 m). These holes showed that overall, the bedrock geology at Paris consists of recrystallised dolomite intruded by several rhyolitic dykes and zones of metasediments. Investigator now believed that the silver epithermal occurrence setting was a Manto style one, of a palaeokarst topography buried beneath the Gawler Range Volcanics, with former mineralising fluids rising from a deeper source (granodiorite) and becoming ponded below the volcanic sequence, to precipitate metals within the karst void space. In early March 2012, a further 5 RC holes for 755 m were drilled on 2 traverses across the larger Helen prospect (PHRC001-005). Here the best intercept obtained was 4 m @ 140 ppm Ag and 8 m @ 0.55 ppm Au. The bedrock geology at Helen likewise consists of rhyolitic dykes intruding metasediments and dolomite. During Year 9, intensive exploration was undertaken at Paris by the JV partners. A round of RC drilling was undertaken with 27 holes drilled for 4027 m (PPRC044-070), but eventually had to be suspended due to persistent drilling problems arising from working with such equipment in the karstic ground, which led to poor sample recovery and excessive drilling product use. Notwithstanding this setback, two phases of diamond drilling were also undertaken at Paris (PPDH007-038, PPDH039-062), via 56 triple-tube cored holes for 9723.53 m (Phase 1 as RC/PQ3/HQ3, Phase 2 as fully PQ3/NQ2 cored from surface). The diamond drilling was designed to generate enough geological and grade information to create a maiden inferred resource estimate. Several geophysical surveys were also run across the Paris prospect. A high-resolution gravity survey consisting of 5127 stations was able to clearly map a dolomitic dome, variability in the NW trending strata, and a complex structural architecture. In March 2012, a 7.6 line-km DD (dipole-dipole configuration) IP/resistivity survey was read at 25 m and 100 m station spacings to generate 5114 data points. At the same time a single but aborted 225 m long line of NanoTEM coverage was acquired, with data collected at 9 sounding positions. Petrological studies were performed on 115 drill core samples, with one high grade silver bearing sample sent for QEMSCAN characterisation to better understand the mineralogy and to metallurgy look for possible hurdles in achieving efficient metallurgical recovery. Investigator also contracted ioGlobal to undertake a litho-geochemistry study using multi-element geochemical data obtained from the drilling programs at Paris. Outside of Paris over the eastern portion of the tenement, further regional soil geochemical surveys were undertaken, utilising partial leach methods (Genalysis, TerraLeach TL8), (1041 collection sites at 500 m centres) and now collecting -2 mm, -180 µm and lag size soil fractions. An additional 3464 in-fill samples were collected over the satellite targets (Helen East, Paris North, Trojan, and Alexander West). High-resolution aerial photographic ortho-imagery and DTM data were also obtained to assist Investigator with understanding the regolith influences across the project area. During Year 10, reporting was done by Sunthe Uranium Pty Ltd (a newly formed 100% owned subsidiary of Investigator Resources). At Paris, work was mostly directed towards generating a maiden inferred resource estimate. Delineation drilling of 84 triple-tube PQ3 cored holes for 9916.57 m (PPDH063-146), 10 RC holes for 1020 m (PPRC071-080) and 1 ACR hole for 97 m. An additional 122 RC holes for 8852 m (PPRC081-202) were put in separately, to scope resource expansion opportunities. Preliminary metallurgical testwork, petrological investigations, assay results wire-framing, resource block-modelling, and robust geological modelling were also being undertaken. The maiden Inferred Mineral Resource for Paris was estimated (and publicised in December 2013) as being 5.9 Mt at 110 g/t Ag (for 20 Moz of contained silver). Using current economic parameters, it was defined as sub-economic, and thus any aim of proceeding to develop Paris on its own, including doing work for converting the deposit’s status to indicated /measured resource categories and pre-feasibility, was not warranted. Accordingly, it was announced that the priority of the JV’s ongoing exploration would be to expand the available resource base by more diligently exploring prospects on the remainder of the tenement. Here the ongoing work comprised further infill soil geochemical sampling (6964 samples) over mid-order silver anomalies, along with rock chip sampling (172). At the Ajax prospect (previously Victory East), 95 rock chip geochemical samples were collected and submitted for assaying. Regolith and outcrop mapping was also undertaken across Helen prospect. VTEM survey data acquired in past government sponsored groundwater research projects were sourced from the GSSA and the Goyder Institute. Gravity surveys were conducted in March 2013 over Alexander West, Helen, and Trojan prospects, when 8952 stations were read on three 60 m x 120 m grids. Drilling was done next, at Alexander East and West and Hector prospects, with 201 ACR holes for 12,851 m drilled to test soil anomalies. Four triple-tube diamond cored holes for 413.72 m were drilled at Alexander West, but results were disappointing with no anomalism detected downhole; the associated surface anomalism was therefore attributed by Sunthe to metal absorption occurring in the near surface calcrete and drainage sediments from diagenetic and erosive dispersions emanating from the Paris prospect. During Year 11, scout drilling was done across the Paris Expanded Target Area (PETA) and regional targets (Ajax, Helen, Helen East, Argos, Ares, Trojan Horse and Hector North) with 142 RC holes for 16,514 m (PPRC203-344). Exploration focus returned to the Nankivel Hill area, with two geophysical surveys conducted, and their data modelled: firstly, parts of an aeromagnetic/radiometric survey giving coverage at both regional and prospect scales, with 3525 line-km flown in February 2014, and thereafter, a ground gravity survey in January-February 2015, consisting of 3084 stations read on a 60 m x 120 m grid. Petrographic studies were performed on 52 drill samples; part of the findings will contribute to a research student’s PhD study currently underway. Further detailed regolith and outcrop mapping was also done across the regional targets, in conjunction with surficial soil (128) and rock chip (101) geochemical sampling. Drill testing of the Helen target (defined by a magnetic and gravity anomaly) intersected some Cu-Au + Ag mineralisation, while drill testing of Argos and Ares and nearby identified Ag-Pb-Zn mineralisation. The drill core of one hole from Paris, PPDH097 (0 - 110.8 m), was scanned in mid 2014 using the GSSA’s Hylogger in collaboration with GSSA technical advisory personnel, in the hope that the findings might contribute to resolving the architecture, controls and relationship of mineralisation. Subsequently, in August 2014, a co-operative research M.O.U. was established with DSD for the continuing application of spectral logging services with GSSA’S Hylogger to the Peterlumbo Project drillhole samples. During Year 12, effort was put into interrogating company datasets to further develop and improve modelling and targeting. A total of 184 rock chip samples were collected from across the licence area, with a particular focus around the Nankivel Hill area, along with further soil sampling (1643). In July 2015, a PACE Initiative (DPY8-31) drilling program was performed in the Nankivel Hill area, consisting of 19 RC holes for 3516 m (PPRC345-362) (ENV12976) that were sited with a focus on understanding the Nankivel Intrusive Complex: which this program significantly increased the knowledge thereof. Petrological samples were taken from rock chip samples (20) during field mapping in addition to selected RC chips (31) obtained during drilling. The GSSA put 3250.1 m of drill cores from 14 Paris prospect diamond holes located on drill Section 7 at the deposit through the Hylogger scanner, besides scanning the drill chips from single RC holes located at the Helen (PPRC334) and Nankivel Hill (PPRC330) prospects. Geological and regolith mapping continued across the tenement at scales of 1:10,000 or lower, utilising the previously acquired ortho-imagery, with a significant proportion of the time spent mapping in the Nankivel Hill area. Trials were begun about using geobotanical studies and HyMapper hyperspectral image interpretation as complementary exploration tools to help map variations in shallowly buried bedrock and its associated in situ regolith. Sunthe reinterpreted the subsurface data from its previous work in order to reinforce confidence about the modelled geology of the Paris deposit, and then was able to increase the estimated inferred silver resource to 8.8 Mt at 116 g/t Ag, containing 33 Moz silver (at a cut-off grade of 50 g/t Ag). During Year 13, exploration activities included diamond and RC drilling programs, mapping of the Nankivel Hills, infill soil sampling and analysis, petrological examination of drill and rock chip samples, detailed regolith and outcrop mapping, data reviews and research and collaboration opportunities. The Paris silver inferred resource estimation was also updated (8.8 million tonnes at 116 g/t silver containing 33 Moz silver (at a cut-off grade of 50 g/t Ag)). Company datasets were further interrogated to develop and improve target models and undertake appropriate drill testing, with a number of targets tested with RC drilling at Nankivel and Ares prospects, plus PACE funded diamond drilling of the Nankivel main magnetic anomaly [PACE DPY9-24]. A single PACE funded diamond hole PPDH147 was drilled to 600.6 m to test the main aeromagnetic anomaly at Nankivel. Within the hole prospective porphyry style alteration and trace copper mineralisation was identified. In follow up to these results, drilling of 3 RC for 899.7 m was completed with the aim of providing vectoring information for the alteration and to test a magnetic anomaly and a stockwork structural zone identified in the area. A broad spread IP survey was conducted at Nankivel in follow up to the drilling, with 7 lines collected on a 400 m spacing. Drilling has further supported that a porphyry style, multi-phase intrusive system may be present. A total of 50 RC (5862 m) and 6 diamond PQ3 twin holes (648.44 m) were completed as part of a Paris Resource infill program to increase the drill density in the core of the deposit while confirming grade continuity. Results were in keeping with previous observations, with ongoing geological interpretation proving up the deposit. Four RC holes for 320 m were competed as part of the Ares Prospect reconnaissance program to follow up an anomaly identified in the 2014 airborne electromagnetic survey. An intensely argillised clay rich layer of altered volcanics are thought to account for the interpreted conductive horizontal cover sequence and is the likely cause of the anomaly. Pyritic sulphides (and occasional sphalerite and galena) were identified in the holes, with only limited Pb, Zn and Ag. Molybdenum anomalism was noted in the holes, and while the significance at this location is unknown, it is noted that is molybdenum is present at a number of prospects including Paris and may prove to be a useful vectoring tool. A total of 5 rock chip samples were collected from quartz vein sets west of Peterlumbo Hill, though no notable mineralisation was identified. Further infill soil sampling was conducted during the reporting period with 117 samples collected across Nankivel and Ares, with results from both areas consistent with previous surveys. A number of rock and drill chip samples were submitted for petrological examination. During Year 14, exploration activities included a drilling program at Paris (29 RC for 8189 m) aimed at confirming the grade continuity. It allowed for an increase in the resource estimate for the Paris deposit by 26% to an estimated 9.3 million tonnes at 139 g/t silver containing 42 Moz silver (cut-off grade remained at 50 g/t Ag). Work commenced on the Paris Prefeasibility Study (geo-metallurgy, geotechnical, hydrological studies etc.). CSA Global Pty Ltd were contracted to derive a simplified preliminary 3D Geometallurgical domain model suitable for selecting composite samples for metallurgical test work from existing bulk samples. Further to the 3D model, the study identified distinctions between the 3 modelled felsic dykes that intersect Paris. An RC drilling program around the perimeter of Paris was undertaken to test the potential for extensions to the north, south and south-east. Drilling south of Paris showed continuity and potential extension of Ag-Pb-Zn mineralised breccia, with mineralised breccia also intersected in the previously undrilled south-east. A gravity survey was completed by Daishsat Geodetic Surveyors to the north of Paris, with 3186 stations collected on a 60 x 120 m grid, with the new data being integrated with existing to allow for continuing interpretation and model development. A regional IP survey was undertaken by Zonge Australia around the Paris, Helen and Diomedes areas, with 42.6 line-km of data collected from 15 lines. The PACE program [DPY9-24] at Nankivel was resumed with the drilling of 4 inclined diamond holes for 1631.4 m (PPDH154-157) (3 PACE & 1 company funded), targeting the demagnetised zone of the Nankivel porphyry system and to follow up prospective alteration and mineralisation intersected during the drilling program. Significant intersections include PPDH155 from 102 m with 6 m @ 0.11% Cu, from 244 m with 3 m @ 0.14% Pb, and hole PPDH157 from 186 m with 3 m @0.14% Pb, and from 180 m with 11m @ 0.14% Zn. Forty-five diamond core samples were submitted to Mason Geoscience Pty Ltd for petrographic description. Follow up RC drilling (20 holes for 2349 m) was completed along the previously completed IP survey line to target similar IP anomalies as were tested in previous drilling and to test an extension to the advanced argillic zone recognized in the diamond drilling. The drilling intersected a persistent flat lying and copper anomalous supergene zone with visible covellite and is thought to be the source of the shallow IP anomalism initially targeted. A large IP anomaly to the south of Nankivel Hill, previously considered a response to graphitic sediment, was reinterpreted and in conjunction with pathfinder geochemistry upgraded to a porphyry Cu-Au target (Trojan target). Petrographic examination was undertaken on 13 RC cutting samples. Three RC holes for 796 m were drilled at the Trojan target, drilling showed that the strongest IP anomaly results from pyrite in a network of fractures and is interpreted to represent the outer pyritic zone of the Nankivel porphyry system with Investigator believing that the drilling overstepped the copper prospective centre of the target. During Year 15 exploration activities included drilling 5 diamond drill holes for preliminary geotechnical assessment of the Paris deposit. Further activities at the Paris deposit included ongoing metallurgical and mineralogical test work, waste characterisation test work, and hydrological baseline water monitoring. The priority program for the year was to progress a pre-feasibility level of study into the Paris Project to determine the viability of the project, however this project was postponed when metallurgical test work identified issues obtaining recoveries in a domain which is interpreted to host 50% of the contained silver in the resource. As a result of the depressed silver price (sitting at between US$14 - $15 per silver ounce) during the year a decision to halt work on the prefeasibility study was made at an early stage to preserve company funds and redirect to other projects. The five PQ3 diamond drill holes were completed for a total length of 614 m. Geotechnical logging was undertaken under the supervision of AMC consultants, with IVR geologists completing the physical logging aspects. An internally conducted waste characterisation study was undertaken by IVR as part of the Pre-Feasibility study. A waste mining inventory was produced using wireframed domains from the Paris Resource cut from the optimised pit shell. Resultant “waste” material was then estimated by type (cover, oxide, transitional breccia, metasediment, dolomite, granite, and dyke material. An estimated 51Mt of “waste” material was produced from the optimised pit on this basis.