b'AEM 2023Short abstractsusers to view and download geoscientific data, includingA synthetic model study was done, evaluating the effect of base airborne electromagnetic (AEM) survey data and inversionfrequency and noise levels (utilising noise samples collected at sections. Much of the AEM data are from surveys acquired inhigh altitude) on a variety of conductance models. The results collaboration with Geoscience Australia and other NSW statewere displayed in different formats to illustrate the combined government departments. Other surveys were acquired byeffects of conductance, base frequency and noise levels on exploration companies. Exploration companies are required toDOI. There is no simple formula or correlation to quantify DOI submit geophysical data to the government. After five years theas a function of all relevant parameters and visual analysis of data can be made publicly available. model and inversion results for relevant conductance models is recommended to determine the best acquisition parameters for Data is free to download, and its use is covered by CC-BYa survey.copyright, which gives the users the right to use distribute, adapt, remix or build upon so long as attribution is given to theThe results highlighted the importance of noise levels author. This abstract provides the reader with instructions oncompared to base frequency to achieve larger depths of how to access AEM data on MinView. investigation and the value of lower base frequencies when exploring for conductive targets in a relatively conductive host environment.AEM-derived watersheds in crystalline domain under volcanic cover Perspectives on AEM processing for geophysical Damien Ciolczyk1, 2, Pierre-Alexandre Reninger1, Clotilde Bertin1,exploration in Canada and worldwideJulien Bernard1, Anne Raingeard1, Pierre Belle3, Lydie Gailler2, Philippe Labazuy2, Guillaume Martelet1 and Olivier Merle2 Magdel Combrinck1. BRGM, Orlans, CENTRE, France NRG, Calgary, AB, Canada2. LMV, Clermont-Ferrand, France Acquiring and processing AEM data in different regions of the 3. Danone Waters, Water Institute by Evian, Evian-les-bains, France world require different approaches and procedures to deliver In the Chane des Puys (CdP, France), volcanic edifices and theirthe best data. Four case histories are discussed to illustrate the emissions cover the weathered conductive low-permeableeffect of jungles, mountains, electrical and magnetic storms basement and fill the palaeo-valleys, hiding the groundwateron AEM and ancillary data. Lesson learned as well as current flows. The 3D delineation of such buried watersheds can beapproaches to deal with challenges in this region are presented. achieved studying variations of conductivity related to primaryThere is no one-size-fits-all processing workflow and critical geological contrasts as well as secondary weathering-inducedevaluation of data an survey conditions are required to deliver contrasts. the best data.We used AEM data to delineate the geometry of the undercoverAn AEM experience in Northern Italy. Innovative and volcanism-basement interface in the northern part of the CdPmultidisciplinary approach for a modern groundwater and derived watersheds. Despite the highly resistive volcanic cover, our processing allowed structural imaging up to aand land managementdepth of investigation of 330 m on average. The processingMatteo Gisolo1, Luca Spagnoli1, Silene Cresseri1 and and inversion of AEM data highlights the interface betweenAndreaViezzoli2a strongly resistant volcanic cover (~104-105 m) and a decametric conductive weathered horizon at the top of the1. A2A S.p.A., Brescia, LOMBARDIA, Italybasement (30-300 .m). 2. Emergo srl , Pisa, ItalyWe picked the weathered horizon of the basement on severalClimate changes are strongly affecting water supply all resistivity profiles, to build an elevation model of its top. Thearound the world and Northern Italy does not make exception newly derived watersheds noticeably differ from the onesto this. In addition, pollutant contamination due to human, proposed in literature. both industrial and farming, activities is increasingly spreading in the high Po Plain region and its lateral valleys. Hence, in 2021 an AEM survey has been conducted, aiming AEM base frequency and depth of investigation at the identification of unknown water reservoirs, on an area Magdel Combrinck1 and Richard Wright2 of about 200 km2 located West of the Garda Lake. A time-domain transient EM system (SkyTEM) has been used to 1. NRG, Calgary, AB, Canada perform airborne measurements.2. Engineering, NRG, Pretoria, Gauteng, South AfricaTo address the complex depositional environments typical of Recent advances in time domain airborne electromagneticthe subalpine region, the resulting geophysical data, joint with (AEM) data acquisition include lower noise levels andlithological data collected from wells in the last decades, have subsequently the use of 12.5 Hz and even 6.25 Hz basebeen interpreted through a cognitive approach. Where neither frequencies instead of the dominant 25 Hz. The mainelectromagnetic nor lithological data were available, a number advantages associated with lower base frequencies areof ground TDEM tests has been performed to cover the lack of increased depth of investigation (DOI) and improved conductorknowledge.The 3D geological model has been constructed discrimination and detection in the high conductance range.manually as a voxel model with lithofacies attributes A study was undertaken to quantify these improvementssupplemented by several bounding surfaces. Two different for the Xcite system that resulted from implementing a newmodelling methods have been combined, namely smooth and suspension system. sharp, allowing to get the geological complexity.AUGUST 2023 PREVIEW 54'