<div>This document defines the technical standards set by Geoscience Australia for the acquisition, processing and supply of airborne magnetic, horizontal magnetic gradient and radiometric (gamma-ray spectrometric) data. The technical standards cover the requirements for equipment, calibrations, quality control checks, reporting and data formats for airborne surveys.</div><div><br></div><div><br></div><div><strong>Table of Contents</strong></div><div><br></div><div>Attachment 1A – Data Acquisition and Processing</div><div><br></div><div>1 Aircraft</div><div>2 Flight and Tie Lines</div><div>3 Global Navigation Satellite System (GNSS)</div><div>4 Parallax Correction</div><div>5 Altimeter</div><div>6 Barometer</div><div>7 Digital Elevation Model</div><div>8 Magnetic System Equipment</div><div>9 Magnetic Gradient System Equipment</div><div>10 Magnetic / Gradient Calibration and Quality Tolerances</div><div>11 Magnetic Base Station (Diurnal Monitoring)</div><div>12 Magnetic Data Reduction</div><div>13 Magnetic Gradient Data Reduction</div><div>14 Radiometric System Equipment</div><div>15 Radiometric Calibration and Quality Tolerances</div><div>16 Radiometric Data Reduction</div><div><br></div><div>Attachment 1B – Reporting and Data Supply</div><div><br></div><div>1 General</div><div>2 Calibration Report</div><div>3 Daily Acquisition Report</div><div>4 Weekly Acquisition Report</div><div>5 Operations and Processing Summary Report</div><div>6 Supply Schedule</div><div><br></div><div>Attachment 1C – Data Formats</div><div><br></div><div>1 General</div><div>2 Point-Located Data Files</div><div>3 Definition Files</div><div>4 Description Files</div><div>5 Raw-Edited Magnetic Data File</div><div>6 Reduced Magnetic Data File</div><div>7 Diurnal Magnetic Data File</div><div>8 Raw-Edited Magnetic Gradient Data File</div><div>9 Reduced Magnetic Gradiometry Data File</div><div>10 Raw-Edited Radiometric Data File</div><div>11 Reduced Radiometric Data File</div><div>12 Gridded Data Files</div><div>13 Image Enhanced GeoTIFF Files

<div>The Australian Sub-bottom Profiling Guidelines were developed by the AusSeabed community to establish a standardised approach to the acquisition of sub-bottom profiler data in an Australian context. They complement a suite of ocean best practice guidelines developed by the AusSeabed community including the <a href="https://pid.geoscience.gov.au/dataset/ga/121571">Australian Multibeam Guidelines</a> (eCat Record 121571) and the Australian <a href="https://repository.oceanbestpractices.org/handle/11329/2080">Satellite Derived Bathymetry Guidelines</a>.</div><div>The guidelines provide recommended procedures for data acquisition, quality checking and data submission to the AusSeabed marine data portal. They were initially designed for use by the Australian Hydrographic Office Hydroscheme Industry Partnership Program (HIPP) to enable the acquisition of standardised, efficient and effective sub-bottom profile data for general seabed characterisation and collection of baseline data. Additionally, the guidelines may be used by any agency or party collecting seabed geophysical data in Australia’s marine jurisdiction for a range of use cases. </div><div><br></div><div>The guidelines include a broad examination of data acquisition, basic processing for quality checking, metadata description, and guidance for data submission to AusSeabed. They do not include prescriptive equipment-specific hardware and software specifications, detailed user-defined settings or instrument preparation activities such as bench/workshop tests, personnel requirements, or provide survey costing information.</div><div><br></div>

Over 8,200 line kilometres of gravity and magnetic data, acquired during the 2020 Otway Basin Seismic Program (OBSP), were combined with public domain survey and satellite data to produce seamless maps of the NW-SE trending deep-water Otway Basin. These data provide valuable information on the geometry and spatial extent of igneous rocks in the deep-water basin. While the top of basement can effectively be imaged from seismic reflection datasets onshore in the Otway Basin, it remains problematic in parts of the deep-water offshore region due to variable seismic data quality. Modelling of the magnetic line data provides an estimate of the depth to the top of basement, an important interface for understanding hydrocarbon prospectivity because it plays a key role in characterising the tectonic evolution of the basin, and thus the thermal maturation history of hydrocarbons. Magnetic modelling was performed using a profile-based curve matching technique producing a depth estimate to the top of the magnetic body that is assumed to be the top of the basement. However, this assumption is flawed where there are volcanic or igneous intra-sedimentary rocks in the basin, as is the case for the Otway Basin where the interpretation of seismic reflection data shows highly reflective events corresponding to igneous features. In most parts of the basin, the modelling results show two layers: a shallow layer (depths < 1000m) corresponding to near surface volcanics, and a deeper layer (depths > 1000m) attributed to the top of the magnetic basement. Magnetic basement shows some similarities with basement picked on seismic reflection data, though in some areas the magnetic basement is shallower. The results also show that the depth to basement is not well resolved in areas with abundant intra-sedimentary igneous rocks. Further investigation is needed in such areas. Presented at the 2024 Australian Society of Exploration Geophysicists (ASEG) Discover Symposium

<div>This report presents key results from the Upper Darling River Floodplain groundwater study conducted as part of the Exploring for the Future (EFTF) program in north-western New South Wales. The Australian Government funded EFTF program aimed to improve understanding of potential mineral, energy, and groundwater resources in priority areas for each resource.</div><div><br></div><div>The Upper Darling River Floodplain study area is located in semi-arid zone northwest New South Wales is characterised by communities facing critical water shortages and water quality issues, along with ecosystem degradation. As such, there is an imperative to improve our understanding of groundwater systems including the processes of inter-aquifer and groundwater-surface water connectivity. The key interest is in the fresh and saline groundwater systems within alluvium deposited by the Darling River (the Darling alluvium - DA) which comprises sediment sequences from 30 m to 140 m thick beneath the present-day floodplain.</div><div><br></div><div>The study acquired airborne, surface and borehole geophysical data plus hydrochemical data, and compiled geological, hydrometric, and remote sensing datasets. The integration of airborne electromagnetic (AEM) data with supporting datasets including surface and borehole magnetic resonance, borehole induction conductivity and gamma, and hydrochemistry data has allowed unprecedented, high resolution delineation of interpreted low salinity groundwater resources within the alluvium and highly saline aquifers which pose salination risk to both the river and fresher groundwater. Improved delineation of the palaeovalley architecture using AEM, seismic, and borehole datasets has permitted interpretation of the bedrock topography forming the base of the palaeovalley, and which has influenced sediment deposition and the present-day groundwater system pathways and gradients.</div><div><br></div><div>The integrated assessment demonstrates that the alluvial groundwater systems within the study area can be sub-divided on the basis of groundwater system characteristics relevant to water resource availability and management. Broadly, the northern part of the study area has low permeability stratigraphy underlying the river and a generally upward groundwater gradient resulting in limited zone of freshwater ingress into the alluvium around the river. A bedrock high south of Bourke partially restricts groundwater flow and forces saline groundwater from deeper in the alluvium to the surface in the vicinity of the Upper Darling salt interception scheme. From approximately Tilpa to Wilcannia, sufficiently permeable stratigraphy in hydraulic connection with the river and a negligible upward groundwater gradient allows recharge from the river, creating significant freshwater zones around the river within the alluvium.</div><div><br></div><div>Hydrometric and hydrochemical tracer data demonstrate that the alluvial groundwater systems are highly coupled with the rivers. Results support the conceptual understanding that bank-exchange processes and overbank floods associated with higher river flows are the primary recharge mechanism for the lower salinity groundwater within the alluvium. When river levels drop, tracers indicative of groundwater discharge confirm that groundwater contributes significant baseflow to the river. Analysis of groundwater levels and surface water discharge indicates that the previously identified declining trends in river discharge are likely to produce the significant decline in groundwater pressure observed across the unconfined aquifer within the alluvium. Improved quantification and prediction of groundwater-surface water connectivity, water level and flux is considered a high priority for both the Darling River and the wider Murray–Darling Basin. This information will assist in understanding and managing water resource availability in these highly connected systems, and enhance knowledge regarding cultural values and groundwater dependent ecosystems (GDEs).</div><div><br></div><div>This study identifies several aquifers containing groundwater of potentially suitable quality for a range of applications in the south of the study area between Wilcannia and Tilpa and assessed the geological and hydrological processes controlling their distribution and occurrence. Potential risks associated with the use of this groundwater, such as unsustainable extraction, impacts on GDEs, and saline intrusion into aquifers or the river, are outside the scope of this work and have not been quantified.</div>

<div>Mount Isa Province in northern Australia is one of the world's most strongly endowed regions for base metals and host to major iron-oxide-copper-gold (IOCG) deposits. The Carpentaria Conductivity Anomaly at the eastern margin of the Province is a major electrical conductivity structure of the Australian continent. We have used magnetotelluric and deep seismic reflection data to image the crustal architecture in this complex region to understand the crustal-scale fluid pathways and potential mineral occurrences. The resistivity models reveal a number of prominent crustal-scale conductors, suggesting that the Carpentaria Conductivity Anomaly is likely caused by a series of isolated or interconnected bodies. These conductors characterise the position and geometry of the ancient Gidyea Suture Zone, interpreted as a west-dipping subduction zone. The conductivity anomaly may record the activity of fluid hydration involved during a subduction event, with the enhanced conductivity likely being caused by deformation or mineralisation of graphitic or sulfidic rocks during orogensis. The distribution of known gold and copper deposits shows a close spatial correlation with the suture zone, suggesting that this structure is potentially a fundamental control on IOCG deposits in its vicinity. The interpretation of the seismic image shows a good correlation with the resistivity models. The implication is that crustal-penetrating structures act as potential pathways for fluid movement to form mineral deposits in the upper crust. The significance of mapping such structures using geophysics is highlighted for mineral exploration.</div><div><br></div>This Abstract was submitted/presented to the 2022 Sub 22 Conference 28-30 November (http://sub22.w.tas.currinda.com/)

<div>The Exploring for the Future program, led by Geoscience Australia, was a $225 million Australian Government investment over 8 years, focused on revealing Australia’s mineral, energy, and groundwater potential by characterising geology.&nbsp;&nbsp;This report provides an overview of activities, results, achievements and impacts from the Exploring for the Future program, with a particular focus on the last four years (2020-2024). &nbsp;</div>

<div>Elastic seismic waves propagate in the solid Earth and contain valuable information for inferring subsurface physical properties. Traditionally, the data acquisition requires active artificial sources for generating seismic waves, which can be air-gun arrays for offshore seismic surveys, and explosive or vibroseis sources for onshore seismic surveys. Active-source seismic data have a wide frequency spectrum often from 4 Hz to 50 Hz and contain reflected and refracted P and S waves and surface waves, which have been widely used for obtaining high-resolution images of subsurface structures across industry and academia in the past decades. In this report, we study the feasibility of combining seismic data from borehole drilling (drilling noise) and the state-of-the-art seismic imaging technique, reverse time migration, for a direct migration (imaging) of drilling-generated seismic noise data without intermediate steps (such as seismic interferometry for virtual common-source seismic data), in the aim of obtaining subsurface structural images. The developed imaging method enables informed decision-making during the drilling process by revealing the three-dimensional structure beneath the drill rig. With precise knowledge of the depth to bedrock and the surrounding geological formations, better planning can be achieved, significantly reducing both costs and time.</div>

<div>Defining and characterising groundwater aquifers usually depends on the availability of data necessary to represent its spatial extent and hydrogeological properties, such as lithological information and aquifer pump test data.&nbsp;In regions where such data is of limited availability and/or variable quality, the characterisation of aquifers for the purposes of water resource assessment and management can be problematic.&nbsp;The Upper Darling River Floodplain region of western New South Wales, Australia, is an area where communities, natural ecosystems and cultural values are dependent on both surface and groundwater resources.&nbsp;Owing to a relative paucity of detailed geological and hydrogeological data across the region we apply two non-invasive geophysical techniques—airborne electromagnetics and surface magnetic resonance—to assist in mapping and characterising the regional alluvial aquifer system.&nbsp;The combination of these techniques in conjunction with limited groundwater quality data helps define an approximate extent for the low salinity alluvial aquifer in a key part of the Darling River valley system and provides insights into the relative water content and its variation within the aquifer materials.&nbsp;This work demonstrates the utility of these key geophysical data in developing a preliminary understanding of aquifer geometry and heterogeneity, thereby helping to prioritise targets for follow-up hydrogeological investigation. Presented at the 2024 Australian Society of Exploration Geophysicists (ASEG) Discover Symposium

<div>This dataset comprises borehole induction conductivity, natural gamma, and nuclear magnetic resonance (NMR) datasets, and surface magnetic resonance (SMR) data collected as part of the Upper Darling Floodplain groundwater study. Associated methods, interpretation, and integration with other datasets are found in the Upper Darling Floodplain geological and hydrogeological assessment (Geoscience Australia Ecat ID:149689). This project is part of the Exploring for the Future (EFTF) program, an eight-year, $225 million Australian Government funded geoscience data and precompetitive information acquisition program. The dataset contains induction conductivity logs and natural gamma logs for 23 bores, NMR logs for 22 bores, and SMR data for 47 sites. The properties inferred from these datasets for hydrogeological characterisation include water content and porosity (borehole NMR and SMR), lithology (natural gamma), and bulk electrical conductivity (induction conductivity).&nbsp;&nbsp;</div><div><br></div>

<div>The Magnetotelluric (MT) Sites database contains the location of sites where magnetotelluric (MT) data have been acquired by surveys. These surveys have been undertaken by Geoscience Australia and its predecessor organisations and collaborative partners including, but not limited to, the Geological Survey of New South Wales, the Northern Territory Geological Survey, the Geological Survey of Queensland, the Geological Survey of South Australia, Mineral Resources Tasmania, the Geological Survey of Victoria and the Geological Survey of Western Australia and their parent government departments, AuScope, the University of Adelaide, Curtin University and University of Tasmania. Database development was completed as part of Exploring for the Future (EFTF) and the database will utilised for ongoing storage of site information from future MT acquisition projects beyond EFTF. Location, elevation, data acquisition date and instrument information are provided with each site. The MT Sites database is a subset of tables within the larger Geophysical Surveys and Datasets Database. </div><div><br></div><div>The resource is accessible via the Geoscience Australia Portal&nbsp;(https://portal.ga.gov.au/), use Magnetotelluric as your search term to find the relevant data.</div>