b'Conferences and eventsNewsresponse as property variations withinInto the mountain: application ofbe successful. Two large surface loops those domains, sensible/stable propertyunderground DHEM at the historicwere laid out in Sept 2021, and three variations were recovered that couldCassilis Gold Mine, Swifts Creekholes probed. Two loops were used due be interpreted in terms of alteration orgoldfield, eastern Victoria to uncertainty about target orientation. exploration targets. DHEM data from MCU0089 (surveyed to N G Direen*1,2, K E Hine3, & B Akhtar3 EOH 120 m) showed a late time, broad, The VHMS exploration criteria wereend of hole response from a source likely translated using the 3D integrated1Mitre Geophysics Pty Ltd, Hobart,to be a great distance away from the hole. model to create exploration vectors2Mitre Geophysics Pty Ltd, Perth, 3MitreModelling defined two poorly located but representative of the mineral system.Geophysics Pty Ltd, Brisbane 70o dipping large plate conductors ~150 m In other words, these vectors werefrom the end of hole MCU089, as well as a numerical realisations of the variousThe hard rock Cassilis gold deposit insmall conductor off another hole, MCU058. targeting criteria. All the explorationthe Swifts Creek goldfield, Victoria, wasThe large plates detected from MCU089 vectors used in the final mineraldiscovered in 1858, after finding ofwere poorly constrained because MCU089 prospectivity analysis were groupedalluvial gold nearby in 1854. It producedwas only 120 m long, and at 150 m past according to three conventional17 t of Cu, and 73,000 oz. of Au atthe end of the hole, only about the first 1/5 categories of exploration criteria: 1)an average grade of 30 g/t betweenof the anomaly has been mapped out by Metal Source; 2) Architecture, effective1880 and 1916. The deposit was minedthe DHEM.conduits and circulation and; 3) Metalunderground in 12 levels over 450 m trapping (deposition). The prospectivityvertical metres; it comprises a seriesTwo new underground diamond holes analysis at Jaguar used a Machineof stacked shear and fault-controlledwere drilled in 2022, TRU001 & 002, Learning approach, namely Randomquartz veins with steep dips (70o) andtargeting the two large plates. Both holes Forests, to generate 3D mineralvariable strikes (041-115o). Criticallyintersected zones of massive pyrrhotite. prospectivity maps based on differentfor geophysical appraisal, the veinsLab measurements showed these to have combinations of input explorationhave selvedges of sulphides includinginductive conductivities of ~10-80 S/m, vectors. massive pyrrhotite, arsenopyrite, pyrite,relative to resistive wall rocks (1500-21 sphalerite, galena, orpiment, realgar, and000 Ohm/m), and assaying indicated Test, evaluate, iterate,native Ag and Cu, up to 1 m thick. Hostvalues 8 g/t Au over multiple intervals GemMidgley. rocks include psammites, sillimanite- in these veins.muscovite-cordierite schists, and sillimanite-K-spar gneisses of the SilurianThis is a story about a Hardrock 3D Seismic Imaging of theOmeo Metamorphic Complex. challenging environment, Mawson Nickel prospect The deposit is in an area of rugged,NickDireen.JJ Leong, Terra Resources heavily timbered terrain with over 600 m relief adjacent to the Cassilis The Mawson prospect is home to a semi- wind gap in the Great Dividing Range,Geophysical mapping for mine massive nickel-copper sulphide discoverywith slopes of 30o gradient, and highplanningthat sits within the Fraser Range Districtannual precipitation, including snow: for of the Albany-Fraser Orogen in Westernexample, Swifts Creek received 113.8 mmChris Wijns, First Quantum MineralsAustralia that also contains the Novaof rain on 6/1/2022, and experienced aAirborne electromagnetic surveys with Bollinger and Silver Knight Deposits.temperature of -6.3o on 7/7/2022. near-surface vertical resolution provide Since its initial discovery, the exploration62 lines of McPhar IP / resistivity surveysrapid and comprehensive coverage programme has been expanded towere acquired over Cassilis in theof a mine site ahead of infrastructure include a 3D seismic survey to define the1960s, but were drilled without success,planning. In environments of sufficient Mawson intrusion architecture. Seismicdue to the rugged topography, andelectrical conductivity contrast, the imaging was performed in pre-stack timeubiquitous disseminated sulphides.data will map variations in the depth migration (PSTM) and pre-stack depthSurface TURAM was acquired in the 70sto bedrock, providing guidance for migration (PSDM), and petrophysicalbut all targets (within 200 of surface)expected excavation depths for solid measurements including P-wavetested by drilling were false positives,building foundations, or mine pre-velocity and density obtained from drillwith many due to pyrite veinlets instrip volumes. Continuous coverage core samples were utilised to build theshear zones, and others interpreted asovercomes the severe areal limitation confidence of seismic velocity model.due to disseminated pyrite in the wallof relying only on drilling and test pits. Several wireline geophysical loggingsrocks. Others were dogged by errorsAn AEM survey in northern Finland that have been conducted recently showin positioning. A DIGHEM II airborneillustrates the success of this approach a strong correlation with key seismicsurvey was flown in 1983, but no recordfor guiding the placement of a mine reflectors associated with the chonolith.can be found of any targets defined orcrusher and related infrastructure. The resulting seismic cube has enableddrill tested. The cost of the EM data collection the chonolith to be mapped below theand interpretation is insignificant in Mawson Fault, which supports the theoryIn 2021, the present license holderscomparison to the US$300 million capital that the intrusion continues at depthengaged Mitre to recommend acost of the mine infrastructure. This below the existing drilling programme. geophysical programme in legacyenvironment of shallow glacial cover underground diamond holes within thechallenges the limits of AEM resolution, If I had unlimited budget, thingsCassilis mine. Initial research and modellingyet analysis of subsequently collected would be different, J.J. Leong. indicated DHEM with surface loops couldthree-dimensional surface seismic 15 PREVIEW FEBRUARY 2023'