b'AEGC 2023Short abstractsThe outputs of this research provide new insights forLoupe surveys for mineral exploration and TSF study.undercover extension of known mineralisation within the Cobar Basin and will assist in future exploration. Gregory Street and Andrew DuncanLoupe GeophysicsDelineation of regolith zones in nickel laterite usingSince last presenting results at an AEGC conference, Loupe electromagnetic imaging: Ravensthorpe, WesternTEM systems have completed dozens of surveys for mineral Australia. exploration, groundwater and engineering applications in Africa, Europe, North America and Australia. The ease of use, Lucy Soares dos Santos and Chris Wijns portability and bandwidth have seen it applied to mineral exploration for base metals, graphite and diamonds as well First Quantum Minerals Ltd as many studies of tailings storage facilities, wetlands, clay Nickel laterite is a product of intensive weathering processesmapping, groundwater exploration, void detection, geological of ultramafic rocks near the surface. The Ravensthorpe Nickelmapping and archaeology.Operation has traditionally used boreholes spaced at 40 mLoupe is usually used at normal walking pace and consists of to delineate the major regolith zones of caprock, limonite,two backpacks, one for the transmitter and one for the receiver. saprolite, and saprock. The high geometric complexityLoupe has the ability to rapidly scan and/or sterilise the near-of the weathering profile leads to an inaccurate resourcesurface (to around 30-40 m depth) for conductivity variations delineation by drilling alone. Loupe is a new ground systemand it can be used in difficult terrain or environmentally-sensitive for transient or time-domain electromagnetic measurementsareas because no vehicles or heavy equipment are required.suitable for resolving shallow electrical conductivity distribution. At Ravensthorpe, the technique was testedResults will be presented from Loupe surveys in mineral in 2019 to improve the spatial resolution of conductivityexploration and tailings storage facilities. We will illustrate the models and, consequently, to better distinguish differentuse of the Loupe system in a range of configurations, including regolith zones. Appraisal of the Loupe system involvedmoving-loop and fixed-loop, and will present data generated by experimentation with different transmitter waveforms,measuring fields from VLF stations and power transmission lines.assessment of diffusion depths and noise levels, and 1D inversions with and without constraining geological input.A development of an unbiased spiral array for MASW Interpretation of the inverted conductivity suggests thatdata acquisition.the Loupe data are imaging the caprock thickness and reproducing the thinner but continuous conductive zonesKoya Sutodefined by downhole logging within certain segments of the regolith profile. Below the caprock, the conductivityAn MASW survey collects data by a linear array of multiple correlates with higher clay proportion, as defined in visualgeophones with a seismic source lined up to one direction. The logging and reflected in higher Al content. data are analysed in the frequency-phase velocity domain to estimate the distribution of dispersion characteristics of surface waves at the survey site. A 1D S-wave velocity profile from MASW AEM survey maps connection between the Carnarvonprocessing is traditionally plotted at the location of the centre Basin and the Capricorn Orogen. of the geophone array regardless of the source direction and offset. The motivation of this paper is to examine the validity of Ned Stolz this tradition. Hayashi and Suzuki (2004) proposed to analyse the data in the common mid-point gather rather than the shot Southern Geoscience Consultants gather. This eliminates the bias related to the source distance An AEM survey near Onslow detected a set of long, linearfrom one array, but requires intense field effort compared with conductors within a low-conductivity corridor interpreteda conventional landstreamer survey. It also does not address the from AEM images and conductivity-depth images. Analysisissue of source direction unless the data are acquired from both and modelling suggest that the AEM conductors occur atends of the geophone array, which doubles the field effort again. depths within the Proterozoic Capricorn Orogen immediatelyWhichever the case, a linear array does not account for variation underneath the conductive sediments of the Cretaceousin the lateral direction to the linear array. A spiral array centred Carnarvon Basin. A complex network of long, linear magneticby a source point is developed to cover multiple azimuths and anomalies also occurs within the low-conductivity corridor.offset distances. A specialised but simple hardware is designed These anomalies are often parallel but not coincident with thefor this survey. This paper shows a result of an experimental linear AEM anomalies. The magnetic anomalies model at depthssurvey comparing with corresponding linear array survey. This within the high-conductivity Carnarvon Basin and all appearsurvey allows to check the validity of the convention of the mid-to terminate at the northern and eastern boundary of the lowarray point used as the location of the solution.conductivity corridor.The low conductivity zone could represent a thinning of the Carnarvon Basin, or a more resistive sub- TIMA and LIBS automated techniques for the basin, or an eroded remnant within the Carnarvon Basin. Themineralogical characterisation of Li-Cu-Ni battery presence of conductive and magnetic bodies at different depthsmetals.and within different stratigraphic units despite their very close spatial relationship suggests that the low conductivity corridorZofia Swierczekmay represent a distinct segment of the Capricorn Orogen which is in turn controlling sedimentation in the overlyingLithium, nickel and copper are among the most critical metals in Carnarvon Basin. modern industry. They are essential components in the medical FEBRUARY 2023 PREVIEW 142'