b'AEGC 2023Short abstractsindustry-standard digestion and analytical techniques, selectedcompared with results from an expensive active reflection to insure near-total geochemical characterisation. seismic survey previously conducted along this road, and with (qualitative) results from a magnetotelluric survey in The extensive geochemical database acquired during thisthis area. At a few locations, core data from drilling produced programme indicates that many deposits of major traditionalhigh-confidence depth-of-cover data. Generally, these data commodities in Queensland are significantly enriched in criticalsets agreed quite well. The ANSWT cover thickness matched minerals, which could underpin profitable critical mineral miningborehole data to within 50-70 m, which is not much worse than industry in the state. This database can also form a baselinethe reflection data estimates (30 m error).of mineral deposit geochemistry for various future research applications and interpretation of exploration results by industry. The HVSR data indicated a much shallower layer interface, even with fairly accurate S-wave velocity values - corresponding to layers within the cover. Nonetheless, HVSR data serve as useful Practical observations of the use of airborneconstraints in ANSWT depth inversion.electromagnetic surveys in covered terrains.The passive seismic data has also been reprocessed assuming a Jarrad Luce sensor spacing of 3000 monly data from 13 nodes. Manual data processing and quality control produced 75 useful dispersion In the exploration for Sediment Hosted Copper deposits,curves in the frequency range 0.33-4 Hz. The depth inversions the mapping of carbonaceous shales is an important step inproduced a low-resolution tomogram with very a similar cover/determining basin structure. This can be efficiently achievedbasement contact. This result suggests a cost-effective use of over large swathes of both exposed and covered terrainsANSWT for cover mapping over prospect or regional scales.through the acquisition of an airborne electromagnetic (AEM) survey. Such a tool, in the form a New Resolution Geophysics Xcite system, was used to acquire approximately 6700 line km ofTrue 3D modeling of land controlled source mixed 12.5 & 25 Hz survey over a large area in the North of theelectromagnetics.Adelaide Rift Complex, South Australia. Over the predominantly exposed terrain, the 25 Hz data was well suited to mappingRandall Mackie, Wolfgang Soyer and Stephen Hallinanthe target carbonaceous shales which are not easily observed at surface due to extensive weathering. However, in coveredCGGterrain the usage of 12.5 Hz to improve investigative capabilityControlled source audio magnetotellurics CSAMT is a beneath cover of increasing conductance was not realised. Ingrounded electromagnetic imaging technique used primarily in comparison, a 6.25 Hz HeliTEM survey acquired over significantthe mining industry and is a closely related predecessor to the cover in Spain yielded an increase in effective depth ofmarine controlled source electromagnetic method CSEM more investigation. Whilst the source of chargeability, as measurablefamiliar to the oil and gas community. Both methods involve in current AEM systems, is thought not to be related toinjecting alternating electric current into the Earth through long mineralisation, the modelling and removal of airborne inducedtransmitter dipoles and making measurements of the Earths polarisation effects is seen to improve the quality of invertedresponse at an array of EM receivers. Historically, CSAMT data conductivity sections. Namely, improvements in both thehave been interpreted using readily available MT modeling delineation of cover thickness and in the geometry of basementalgorithms, but this means using only the data considered far conductors, both of which can significantly impact the planningenough away from the dipole source (far-field zone) to be of subsequent drill programmes. interpretable using MT modeling algorithms that assume a uniform source field. Our algorithm RLM-3D can invert E and/Cover mapping using ambient noise surface waveor H field data as well as impedances and in this talk we show tomography and horizontal-to-vertical spectral ratiosexamples for both synthetic models and real CSAMT survey at a prospect near Boulia, Queensland, Australia. data. The results will demonstrate the advantages, particularly compared to standard far-field only modeling, of including all Richard Lynch 1 Anais Lavoue1, Nicholas Arndt1 and Charlesfrequencies, the actual transmitter and receiver sensor locations, Beard2 and the topography in the 3D inversion. The ability now to efficiently incorporate the transition-zone data in 3D inversion 1 Sisprobe SASshould allow more flexibility in survey arrays, addressing the 2 Cambridge University current far field only practice of keeping the transmitter far A relatively new passive seismic method - ambient noisefrom the receiver array. Joint 3D inversion with MT data (e.g., surface wave tomography (ANSWT)was applied to imagecollected overnight on the same array) of course adds depth to the cover/basement contact on a prospect near Boulia 200the 3D resistivity volumes.km south of Mt Isa in Queensland, Australia. The horizontal-to-vertical spectral ratio (HVSR) method was also appliedAirborne Superheterodyne Sulphide Exploration to the continuous seismic dataset for comparison. The dataTechnique (ASSET).was collected by 100 triaxial self-contained nodes deployed along a 30 km section of rural road for a period of 19 days inJames MacnaeDecember 2019.Recent developments have investigated and shown some The S-wave velocity tomogram obtained by the ANSWT methodpromise that heterodyne measurements over the Kempfield down to 2 km below surface shows a clear subhorizontaldeposit in NSW can distinguish sulphide Induced Polarisation inferface at about 700 m depth where the velocity increases(IP) anomalies from graphite. In airborne electromagnetic from roughly 2500 m/s to 3500 m/s. This contact can be(EM) exploration, an ongoing aim has been to distinguish FEBRUARY 2023 PREVIEW 116'