Western Australia
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<div>Komatiites are extinct volcanic rocks that formed by partial melting of 20-50% of their mantle source – a unique feature that allows us to understand the composition of the mantle in the early Earth. Due to their high temperature, komatiites incorporate proximal rock types on their way to, and on, the Earth’s surface. In this craton-scale study, we looked to use this property of komatiite magmas to track their interaction with the crust of the Yilgarn Craton. The results yielded Hf and Nd isotope arrays (Figure 1), that potentially have three components. The first likely represents the depleted mantle source of the magmas, and most plot in the region between +2 and +6 εHfi and 0 to +3.3 εNdi. The second source represents a more unradiogenic component, most likely 3.5-3.3 Ga continental crust (minimum). This component is more notable in the 2.8 and 2.9 Ga events with values trending to CHUR and negative εNd. The 2.8 Ga dataset, and particularly the komatiitic basalts from the Marda region, appear to show the most contamination with old crust. This is likely due to this area representing the old nucleus of the craton, as shown in Hf-isotope mapping. The final component represents an ultra-depleted source. Data from Ravensthorpe, Mt Clifford, and Wiluna show trends towards this source referred to as the Early Refractory Reservoir (ERR)(Nebel et al. 2014). We suggest that the 2.7 and 2.9 Ga plumes interacted with refractory Hadean plume residues, which constitute the ERR, within the Yilgarn lithosphere. Isotopic data on crustal rocks suggests the Yilgarn may have formed in the Hadean to Eoarchean, and hence the ERR could represent the residue of the Hadean crust generation process that formed the low Lu/Hf Jack Hills zircons. If correct, this suggests that the ERR survived for much longer than previously thought, as a rare component within the Earth’s oldest cratons.</div> This Abstract was submitted/presented to the 2023 6th International Archean Symposium (6IAS) 25 - 27 July (https://6ias.org/)
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Lithified, drowned coastal dunes preserved below sea-level on continental shelves are rarely observed. Here we present new insights into the evolution of the Rottnest Shelf, southwestern Australia, where drowned parabolic dunes have been identified in high-resolution multibeam bathymetry (Figure 1). In 2012 Geoscience Australia undertook a marine survey of the warm temperate, carbonate-dominated, sediment-starved Rottnest Shelf, overlying the Vlaming Sub-basin, southwest Australia. This work supports an assessment of the CO2 storage potential of the basin, part of the Australian Government's National CO2 Infrastructure Plan. The survey acquired a range of data for sedimentological, geochemical and biological characterisation of the seabed, including multibeam sonar bathymetry and backscatter, side-scan sonar, acoustic sub-bottom profiles, towed underwater video and grab samples. Two areas were surveyed, one each north and south of Rottnest Island. The seabed surface comprised plains, ridges, and nested parabolic dunes, as well as high-relief mounds, shallow depressions, sediment waves, rhodolith beds and fault scarps. The seabed is dominantly a hard carbonate surface thinly veneered with biogenic carbonate sediment. Parabolic and crescent shaped ridges, with steep landward-facing slopes, form the most conspicuous features, with up to 10 m of relief above the seabed (water depths of 29-54 m). The ridges are interpreted to be the remnants of Late Quaternary coastal barriers and dunefields. Annular ridges are present within fields of parabolic ridges, the latter supporting high densities of sessile biota including hard corals, macroalgae, red algae, massive sponges and bryozoans. Here we propose a model to account for the geomorphic development of the Rottnest Shelf that relates the formation of the relict barrier dune system to eustatic changes in sea-level, prevailing winds and sediment supply. Additional factors considered include local variability in hydrodynamic regime and its interaction with geomorphic features.
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<div>Archean greenstone belts are a vital window into the tectonostratigraphic processes that operated in the early Earth and the geodynamics that drove them. However, the majority of greenstone belts worldwide are highly-deformed, complicating geodynamic interpretations. The volcano-sedimentary sequence of the 2775-2690 Ma Fortescue Group is different in that it is largely undeformed, offering a unique insight into the architecture of greenstone sequences. In the Fortescue magmatic rocks, geochemical signatures that in deformed belts in the Superior or Yilgarn Cratons might have been interpreted as arc-like, are explained by contamination of rift-related mantle and plume-derived magmas with Pilbara basement crust; understanding the wider geological and structural setting allows a more complete interpretation.</div><div> However, contamination of Fortescue magmas by an enriched sub-continental mantle lithosphere (SCLM) is an alternative hypothesis to the crustal contamination model. If demonstrated, the addition of sediments and fluids to the SCLM, required to form enriched/metasomaytised SCLM, would suggest active subduction prior to the Neoarchean. To test this hypothesis, we collected Hf-O isotopic data on zircons from felsic volcanic rocks throughout the Fortescue Group; if the contamination had a subducted sedimentary component (δ18O>20‰), then the O-isotopes should record a heavy signature.</div><div> The results show that the ca. 2775 Ma Mt Roe Formation has εHfi from 0 to -5.6, and δ18OVSMOW of +4.8- +0.3‰, with the majority of values <+3‰. The ca. 2765 Ma Hardey Formation (mostly sediments) has highly unradiogenic εHfi of -5 to -9.4, and δ18O of +7.8- +6.6‰. The ca. 2730 Ma Boongal Formation displays similar values as for Mt Roe, with εHfi +1.9 to -5.5 and δ18O +3.0 to -0.6‰. The ca. 2720 Ma Tumbiana Formation shows the greatest range in εHfi from +4.9 to -4.6, with δ18O +7.1- +0.7‰, with the majority between +4.5 and +2.5‰. Data from the 2715 Ma Maddina Formation are more restricted, with εHfi between +4.0 and -0.1, and δ18O +5.0- +3.8‰. The youngest formation, the 2680 Ma Jeerinah Formation, has εHfi +2.3 to -6.2, and δ18O +5.1 to -2.1‰.</div><div> Importantly, these data provide little evidence of a cryptic enriched SCLM source in the Fortescue magmas. Furthermore, the dataset contains some of the lightest δ18O data known for Archean zircon, highlighting a ca. 100 Myr period of high-temperature magma-water interaction, with long-term continental emergence implied by the trend to meteoric δ18O compositions. The exception to this is the Hardey Formation, which may have formed via crustal anatexis in a period of reduced heat-flow between the 2775-2665 and 2730-2680 Ma events. Data from the other formations show a broad trend of increasing δ18O and εHf from 2775 to 2680 Ma. We suggest this represents the effects of progressive cratonic rifting, allowing mantle-derived magmas to reach the surface less impeded, and also a decreasing role of meteoric water in the rift zone as the sea invades. As a result, the εHf and δ18O data from the Fortescue Group represent the evolving nature of an Archean rift zone, from an emergent volcanic centre, to a submarine environment.</div><div><br></div>This Abstract was submitted/presented to the 2023 6th International Archean Symposium (6IAS) 25 - 27 July (https://6ias.org/)
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<div>AusAEM Western Resources Corridor Survey: Logistics Report, AEM Data, and GALEI conductivity estimates.</div><div><br></div><div>From May to October 2022, an airborne electromagnetic (AEM) survey was flown over parts of Western Australia, Northern Territory and South Australia. Geoscience Australia commissioned the survey in collaboration with the Geological Surveys of Western Australia (GSWA) and South Australia (GSSA) as part of the Australian Government's Exploring for the Future program and the Western Australian Government's Exploration Incentive Scheme.</div><div><br></div><div>A total of 58,858 line kilometres of new data were acquired. GA managed all aspects of the acquisition, quality control and processing of the AEM data.</div><div><br></div><div>The survey was flown by Xcalibur Aviation (Australia) Pty Ltd using its TEMPEST AEM system. The survey was flown in variable line directions and line spacings ranging from 20km to 5km apart. Skytem Australia Pty Ltd also processed the data. This data package includes the acquisition and processing report, the final processed AEM data, and the results of the contractor's conductivity-depth estimates. The data package also contains the results and derived products from a 1D inversion by Geoscience Australia with its own inversion software.</div><div><br></div><div>Geoscience Australia's Exploring for the Future program provides pre-competitive information to inform decision-making by Government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. We are building a national picture of Australia's geology and resource potential by gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia's transition to a low emissions economy, strong resources and agriculture sectors, and economic opportunities and social benefits for Australia's regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight-year, $225m investment by the Australian Government.</div><div><br></div><div>The survey will become part of the national AusAEM airborne electromagnetic acquisition program, which aims to provide geophysical information to support investigations of the regional geology and groundwater system and better characterise the salinity, recharge and architecture of the aquifers within the upper few hundred metres of the subsurface. It will also provide data to allow for the study of trends in regolith thickness and variability, variations in bedrock conductivity, the conductivity of key bedrock (lithology-related) conductive units under cover; and (d) the groundwater systems of the region at a reconnaissance scale.</div>
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Interpretation of newly acquired seismic data in the northern Houtman Sub-basin (Perth Basin) suggests the region contains potential source rocks similar to those in the producing Abrolhos Sub-basin. The regionally extensive late Permian–Early Triassic Kockatea Shale has the potential to contain the oil-prone Hovea Member source interval. Large Permian syn-rift half-graben, up to 10 km thick, are likely to contain a range of gas prone source rocks. Further potential source rocks may be found in the Jurassic-Early Cretaceous succession, including the Cattamarra Coal Measures, Cadda shales and mixed sources within the Yarragadee Formation. This study investigates the possible maturity and charge history of these different source rocks. A regional pseudo-3D petroleum systems model is constructed using new seismic interpretations. Heat flow is modelled using crustal structure and possible basement composition determined from potential field modelling, and subsidence analysis is used to investigate lithospheric extension through time. The model is calibrated using temperature and maturity data from 9 wells in the Houtman and Abrolhos sub-basins. Source rock properties are assigned based on an extensive review of TOC, Rock Eval and kinetic data for the offshore northern Perth Basin. Petroleum systems analysis results show that Permian, Triassic and Early Jurassic source rocks may have generated large cumulative volumes of hydrocarbons across the northern Houtman Sub-basin, whilst Middle Jurassic‒Cretaceous sources remain largely immature. However the timing of hydrocarbon generation and expulsion with respect to trap formation and structural reactivation is critical for the successful development and preservation of hydrocarbon accumulations.
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The product consists of 5,291 line kilometres of time-domain airborne electromagnetic (AEM) geophysical data acquired in the Fitzroy River Catchment of the West Kimberley region, the electrical conductivity models derived from the dataset, and the survey operations and processing report. The data were acquired using the heliborne SkyTEM-312 AEM system. A locality diagram for the survey is shown below. The survey was funded by the Government of Western Australia, as part of its Water for Food Initiative, through the Department of Water (WA DoW). The survey was managed by Geoscience Australia as part of a national collaborative framework project agreement with WA DoW. The aim of the survey was to map the electrical properties of the top 200-300 metres of the sub-surface geology and hydrogeology within the study area. Geoscience Australia contracted SkyTEM Australia Pty Ltd to acquire the AEM data using the SkyTEM-312 system in September and October 2015. The data were also processed by SkyTEM Australia Pty Ltd using its in-house processing and inversion techniques. The Kimberley Region in north-west Australia is a priority area for the development of irrigated agriculture. The hydrogeology of the area is poorly understood, hence the primary aim of the AEM survey was to provide geophysical data in support of groundwater investigations. Specific objectives of the AEM survey included mapping the extent of regional Canning Basin aquifers to aid assessment of groundwater resources and sustainable yield estimates for agricultural development; provide AEM data in transects to underpin studies of surface-groundwater interactions (groundwater discharge and recharge potential) associated with the major rivers, and permanent river pools in particular; detect and assess potential groundwater salinity hazards within proposed irrigation areas; and map the seawater intrusion (SWI) interface. Very specific mapping objectives were developed for each sub-area, and the survey was designed with these detailed local objectives in mind. The survey design reflects two scales of investigation: 1. Two areas (Knowsley-Mowanjum and GoGo-Fitzroy Crossing) with higher density flight line spacing (400 m) in areas with advanced plans for development of irrigated agriculture; 2. Irregular grid of regional transects and lines acquired along river tracts reflecting the reconnaissance nature of regional investigations in a frontier hydrogeological area. Much of the area lies underneath cover of sedimentary basins and is a poorly-understood element of Australia¿s geology. The Fitzroy Trough is also host to a number of mineral systems including diamonds and base metal mineralisation, as well as shale gas resources. The survey data should assist with understanding of the basin geology and neotectonics, while lamproite pipes have also been intersected in a number of flight lines. The survey data will also add to the knowledge of the thickness and character of alluvium and regolith cover and will inform future geological mapping in the region. The data will be available from Geoscience Australia¿s web site free of charge. The data release package includes: 1. Point-located electromagnetic line data with associated position, height, orientation, transmitter current, and derived ground elevation data. These data are in ASCII column format with associated ASEG-GDF2 header files. All regular survey, repeat lines and high altitude lines are included in the dataset. The dataset is split into Parts 1 and 2 based on the differences in the receiver gate times for each part. 2. Point-located magnetic line data with associated position, height, orientation, and derived ground elevation data. These data are in ASCII column format with associated ASEG-GDF2 header files. All regular survey, repeat lines and high altitude lines are included in the dataset. 3. Point-located line data for conductivity estimates derived by SkyTEM Australia Pty Ltd using its Automated Laterally Constrained Inversion (aLCI) algorithm with associated position, height, orientation, and derived ground elevation data. Data include the conductivity estimate for each of the 30 inversion model layers, the layer elevation, estimated depth of investigation, and data fit residuals. These data are in ASCII column format with associated ASEG-GDF2 header files. All regular survey and repeat lines are included in the dataset. 4. Gridded data for the derived ground elevations, total magnetic intensity, and the conductivity of the 30 aLCI inversion model layers. The grids are in ER Mapper® binary raster grid format with associated header files. The grids have a cell size of 100 m. For the aLCI inversion layer conductivity grids, there are versions that are masked (set to undefined) below the estimated depth of investigation and unmasked. 5. Graphical multiplots and spatial images derived from the aLCI inversion. The multiplots show the derived aLCI conductivity depth sections and selected data panels for each individual flight line in Portable Network Graphics (PNG) and Portable Document Format (PDF) formats. The spatial images show colour images of the conductivity for each aLCI model layer and are in PNG, PDF and geo-located Tagged Image Format (TIF) files suitable for use in MAPINFO. 6. The survey Operations and Processing Report, which provides the details of the AEM system, logistics, data acquisition, data processing and the aLCI inversion parameters. 7. ESRI shapefiles and KML files of flight lines. Summary Survey Name West Kimberley Airborne EM Survey, WA, 2015 (Water for Food) State Western Australia Sub Region West Kimberley Area 20,314 km2 Line km 5,291 km Survey Completed 17 October 2015 AEM system SkyTEM-312 Processing SkyTEM Australia Pty Ltd
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Carnarvon Shelf reef polygons were manually digitized from multibeam echosounder datasets collected on marine survey GA0308 in August/September 2008. Reef areas were defined as exposed, hard substrate that are often raised above the surrounding seafloor. They were mapped using bathymetry and backscatter data along with bathymetric derivatives including; slope, hillshaded bathymetry and contours. Features were mapped at a scale of 1:10 000. This dataset is published with the permission of the CEO, Geoscience Australia.
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<div>This dataset represents the second version of a compilation of borehole stratigraphic unit data on a national scale (Figure 1). It builds on the previous Australian Borehole Stratigraphic Units Compilation (ABSUC) Version 1.0 (Vizy & Rollet, 2023a) with additional new or updated stratigraphic interpretation on key boreholes located in Figure 2. Its purpose is to consolidate and standardise publicly accessible information from boreholes, including those related to petroleum, stratigraphy, minerals, and water. This compilation encompasses data from states and territories, as well as less readily available borehole logs and interpretations of stratigraphy.</div><div> </div><div>This study was conducted as part of the National Groundwater Systems (NGS) Project within the Australian Government's Exploring for the Future (EFTF) program. Geoscience Australia’s Exploring for the Future program provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia’s transition to net zero emissions, strong, sustainable resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government. More information is available at http://www.ga.gov.au/eftf and https://www.eftf.ga.gov.au/national-groundwater-systems.</div><div> </div><div>As our understanding of Australian groundwater systems expands across states and territories, including legacy data from the 1970s and recent studies, it becomes evident that there is significant geological complexity and spatial variability in stratigraphic and hydrostratigraphic units nationwide. Recognising this complexity, there is a need to standardise diverse datasets, including borehole location and elevation, as well as variations in depth and nomenclature of stratigraphic picks. This standardisation aims to create a consistent, continent-wide stratigraphic framework for better understanding groundwater system for effective long-term water resource management and integrated resource assessments.</div><div> </div><div>This continental-scale compilation consolidates borehole data from 53 sources, refining 1,117,693 formation picks to 1,010,483 unique records from 171,396 boreholes across Australia. It provides a consistent framework for interpreting various datasets, enhancing 3D aquifer geometry and connectivity. Each data source's reliability is weighted, prioritising the most confident interpretations. Geological units conform to the Australian Stratigraphic Units Database (ASUD) for efficient updates. Regular updates are necessary to accommodate evolving information. Borehole surveys and dip measurements are excluded. As a result, stratigraphic picks are not adjusted for deviation, potentially impacting true vertical depth in deviated boreholes.</div><div> </div><div>This dataset provides:</div><div>ABSUC_v2 Australian stratigraphic unit compilation dataset (ABSUC)</div><div>ABSUC_v2_TOP A subset of preferred top picks from the ABSUC_v2 dataset</div><div>ABSUC_v2_BASE A subset of preferred base picks from the ABSUC_v2 dataset</div><div>ABSUC_BOREHOLE_v2 ABSUC Borehole collar dataset</div><div>ASUD_2023 A subset of the Australia Stratigraphic Units Database (ASUD)</div><div> </div><div>Utilising this uniform compilation of stratigraphic units, enhancements have been made to the geological and hydrogeological surfaces of the Great Artesian Basin, Lake Eyre Basin and Centralian Superbasin. This compilation is instrumental in mapping various regional groundwater systems and other resources throughout the continent. Furthermore, it offers a standardised approach to mapping regional geology, providing a consistent foundation for comprehensive resource impact assessments.</div>
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Geoscience Australia’s Exploring for the Future (EFTF) program provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia’s transition to a low emissions economy, strong resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government. Further detail is available at http://www.ga.gov.au/eftf. The National Groundwater Systems (NGS) project, is part of the Australian Government’s Exploring for the Future (EFTF) program, led by Geoscience Australia (https://www.eftf.ga.gov.au/national-groundwater-systems), to improve understanding of Australia’s groundwater resources to better support responsible groundwater management and secure groundwater resources into the future. The project is developing new national data coverages to constrain groundwater systems, develop a new map of Australian groundwater systems and improve data standards and workflows of groundwater assessment to populate a consistent data discovery tool and web-based mapping portal to visualise, analyse and download hydrogeological information. While our hydrogeological conceptual understanding of Australian groundwater systems continues to grow in each State and Territory jurisdiction, in addition to legacy data and knowledge from the 1970s, new information provided by recent studies in various parts of Australia highlights the level of geological complexity and spatial variability in stratigraphic and hydrostratigraphic units across the continent. We recognise the need to standardise individual datasets, such as the location and elevation of boreholes recorded in different datasets from various sources, as well as the depth and nomenclature variations of stratigraphic picks interpreted across jurisdictions to map such geological complexity in a consistent, continent-wide stratigraphic framework that can support effective long-term management of water resources and integrated resource assessments. This stratigraphic units data compilation at a continental scale forms a single point of truth for basic borehole data including 47 data sources with 1 802 798 formation picks filtered to 1 001 851 unique preferred records from 171 367 boreholes. This data compilation provides a framework to interpret various borehole datasets consistently, and can then be used in a 3D domain as an input to improve the 3D aquifer geometry and the lateral variation and connectivity in hydrostratigraphic units across Australia. The reliability of each data source is weighted to use preferentially the most confident interpretation. Stratigraphic units are standardised to the Australian Stratigraphic Units Database (ASUD) nomenclature (https://asud.ga.gov.au/search-stratigraphic-units) and assigned the corresponding ASUD code to update the information more efficiently when needed. This dataset will need to be updated as information grows and is being revised over time. This dataset provides: 1. ABSUC_v1 Australian stratigraphic unit compilation dataset (ABSUC) 2. ABSUC_v1_TOP A subset of preferred top picks from the ABSUC_v1 dataset 3. ABSUC_v1_BASE A subset of preferred base picks from the ABSUC_v1 dataset 4. ABSUC_BOREHOLE_v1 ABSUC Borehole collar dataset 5. ASUD_2023 A subset of the Australia Stratigraphic Units Database (ASUD) This consistent stratigraphic units compilation has been used to refine the Great Artesian Basin geological and hydrogeological surfaces in this region and will support the mapping of other regional groundwater systems and other resources across the continent. It can also be used to map regional geology consistently for integrated resource assessments.
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AusAEM 02 Airborne Electromagnetic Survey, NT /WA, 2019-2020: TEMPEST® AEM data and conductivity estimates The accompanying data package, titled “AusAEM 02 WA/NT, 2019-20 Airborne Electromagnetic Survey: TEMPEST® airborne electromagnetic data and conductivity estimates”, was released on 10 August 2020 by Geoscience Australia (GA), the Geological Survey of Western Australia and the Northern Territory Geological Survey. The package contains processed data from the“AusAEM 02 WA/NT, 2019-20 Airborne Electromagnetic Survey" that was flown over the North-West part of the Northern Territory across the border and all the way to the coast into Western Australia. The regional survey was flown at a 20-kilometre nominal line spacing and entailed approximately 55,675 line kilometres of geophysical data. The survey was flown in two tranches during 2019, by CGG Aviation (Australia) Pty. Ltd. under contract to Geoscience Australia, using the TEMPEST® airborne electromagnetic system. CGG also processed the data. The survey also includes a further 6,450 line kilometres of infill flying that was funded by private exploration companies, acquired in certain blocks within the survey area. The data from these infill blocks have been processed in the same manner as the regional lines and are part of this release. Geoscience Australia commissioned the AusAEM 02 survey as part of the Exploring for the Future (EFTF) program, flown over parts of the Northern Territory and Western Australia. Geoscience Australia (GA) leads the EFTF program, in collaboration with the State and Territory Geological Surveys of Australia. The program is designed to investigate the potential mineral, energy and groundwater resources of Australia driving the next generation of resource discoveries. GA managed the survey data acquisition, processing, contract, the quality control of the survey and generating two of the three inversion products included in the data package. The data release package comntains 1. A data release package summary PDF document. 2. The survey logistics and processing report and TEMPEST® system specification files 3. ESRI shape files for the regional and infill flight lines 4. Final processed point located line data in ASEG-GDF2 format 5. Conductivity estimates generated by CGG’s EMFlow conductivty-depth transform -point located line data output from the inversion in ASEG-GDF2 format -graphical (PDF) multiplot conductivity sections and profiles for each flight line -Grids generated from CGG's inversion conductivty-depth transform in ER Mapper® format (layer conductivities) 6. Conductivity estimates generated by Geoscience Australia's inversion -point located line data output from the inversion in ASEG-GDF2 format -graphical (PDF) multiplot conductivity sections and profiles for each flight line -georeferenced (PNG) conductivity sections (suitable for pseudo-3D display in a 2D GIS) -GoCAD™ S-Grid 3D objects (suitable for various 3D packages)