Airborne Electromagnetics
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Airborne Electromagnetic data were acquired by Geoscience Australia in areas considered to have potential for uranium or thorium mineralisation under the Australian Government's Onshore Energy Security Program (OESP). The surveys have been managed and interpreted by Geoscience Australia's Airborne Electromagnetic Acquisition and Interpretation project. Government of South Australia Department for Manufacturing, Innovation, Trade, Resources and Energy (DMITRE), formerly the Department of Primary Industries and Resources South Australia (PIRSA), which changed name in October 2011 purchased infill. Three survey areas were recognised in the Frome AEM survey area and Cariewerloo traverses. Industry paid for infill - all of this data has now been released to the public domain and is available at the GA website. In contrast to industry style deposit scale investigations, these surveys are designed to reveal new geological information at regional scale. The Frome airborne electromagnetic data were acquired at line spacing's of between one and five kilometres, a total of 32 317 line km and covers an area of 95 450 km squared. The outcomes of the Frome AEM survey include mapping of subsurface geological features that are associated with unconformity-related, sandstone-hosted and palaeovalley-hosted uranium mineralisation. The data are also capable of interpretation for other commodities including metals and potable water as well as for landscape evolution studies. The improved understanding of the regional geology resulting from the Pine Creek survey results will be of considerable benefit to mining and mineral exploration companies. This Data Package is for Archive to the internal area of the CDS and contains all data, grids, images, mxd, shape files, documentation, licenses, agreements, interpretations and scripts used to create the Frome deliverables. At the projects completion (2012) all directories are required to be moved off the NAS. The reason to keep all the files is that more work is to be done on this data in the 2012-2015 period and these files may be needed in this future work.
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The Frome airborne electromagnetic (AEM) survey (Figure 1) was designed to deliver reliable, pre-competitive AEM data and scientific analysis for the energy resource potential of the Frome region of South Australia. The Frome AEM survey is the last and largest of three regional AEM surveys flown under the 5-year Onshore Energy Security Program (OESP) by Geoscience Australia (GA) in the interests of reducing risk and stimulating exploration investment for uranium. The Frome AEM survey was flown between 22 May and 2 November 2010, is approximately 95 450 km2 in area and collected 32 317 line km of new data at an average flying height of 100 m. The Frome survey complements earlier surveys in the Paterson Province (Western Australia; Roach, 2010) and the Pine Creek area (Northern Territory; Craig, in prep.). The Frome survey was flown in conjunction with the PIRSA Cariewerloo Basin survey (Hutchinson and Costelloe, 2010; PIRSA, 2010; Wilson et al., 2011) using the same aircraft and survey parameters. The Frome AEM survey includes the Marree (pt), Callabonna (pt), Copley (pt), Frome (pt), Parachilna (pt), Curnamona, Olary and Chowilla (pt) 1:250 000 sheets and was flown largely at 2.5 km line spacing, with the northern portion flown at 5 km line spacing (Figure 1). Survey partners included GA, PIRSA and an industry consortium. The survey aims to assist regional-scale mapping of subsurface geological features associated with uranium systems as well as general geological and groundwater mapping. The geological features targeted by the AEM mapping program include: - Palaeochannel-hosted sandstone uranium systems in the Frome Embayment; - Faults which may have acted as fluid pathways (e.g., the Poontana and Wooltana faults); - The Benagerie Ridge (a buried Paleoproterozoic basement high in the Curnamona Province); - Thickness of cover sediments over Proterozoic and Paleozoic rocks; - Units within the Namba Formation, particularly the Beverley Sands, which are prospective for uranium deposits, overlying the Alpha Mudstone; - Cenozoic strandlines for heavy mineral deposits in the Murray Basin; - Erosion surfaces on Mesozoic which may constrain Cenozoic valley development; - Proterozoic basement sulfide deposits (e.g., White Dam Au, Portia Cu-Au-Mo, Mutooroo Cu-Co-Au, Kalkaroo Cu-Au); - Proterozoic basement iron ore deposits (e.g., Mutooroo, Razorback Ridge); - The Delamerian Orogen under the Murray Basin; and, - Groundwater. The survey results indicate a depth of investigation (depth of reliable signal penetration) of up to 400 m in areas of thin cover and resistive basement (e.g., Adelaidean rocks in the Olary Ranges) and up to about 100-150 m in Cenozoic Mesozoic sediments in the Frome Embayment and Murray Basin. A range of under-cover features are revealed, including (but not limited to): extensions to known palaeovalley networks in the Frome Embayment; the under-cover extent of the Benagerie Ridge; regional faults in the Frome Embayment and Murray Basin; folded and faulted Neoproterozoic rocks in the Adelaide Fold Belt; Cenozoic Mesozoic stratigraphy in the Frome Embayment; neotectonic offsets in the Lake Eyre Basin; conductive Neoproterozoic rocks associated with copper-gold mineralisation; and, coal-bearing structures in the Leigh Creek area. Phase 1 (contractor-delivered) data (Hutchinson, 2011) are now available for free download from: http://www.ga.gov.au/energy/projects/airborne-electromagnetics.html or on DVD-ROM ($99) from the GA Sales Centre.
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Airborne Electromagnetic data are being acquired by Geoscience Australia in areas considered to have potential for uranium or thorium mineralisation under the Australian Government's Onshore Energy Security Program (OESP). The surveys have been managed and interpreted by Geoscience Australia's Airborne Electromagnetic Acquisition and Interpretation project. In contrast to industry style deposit scale investigations, these surveys are designed to reveal new geological information at regional scale. The Paterson airborne electromagnetic data were acquired at line spacings of between one and six kilometres, a total of 28 200 line km and covers an area of 47 600 km<sup>2</sup>. The outcomes of the Paterson AEM survey include mapping of subsurface geological features that are associated with unconformity-related, sandstone-hosted and palaeovalley-hosted uranium mineralisation. The data are also capable of interpretation for other commodities including metals and potable water as well as for landscape evolution studies. The improved understanding of the regional geology resulting from the Paterson survey results will be of considerable benefit to mining and mineral exploration companies. Phase-1 data, that is, contractor quality-controlled and quality-assessed data, were released during 2009. Phase-2 data, that is Geoscience Australia layered earth inversion (GA-LEI) data and derived products, are included in this data release. The data and products described in this report are contained on the accompanying DVD. The main products from the AEM survey are conductivity depth slices and sections, conductance grids and an AEM Depth of Investigation grid. The data is provided in formats which can be viewed on most computers systems. They include, JPEG (.jpg) with associated world files for easy use in geographic information system (GIS) packages, ER Mapper grids (.ers), ESRI shape files (.shp) of the flight path, and point-located ASCII data with relevant metadata for derived products.
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The Australian Government, through Geoscience Australia, funded an airborne electromagnetic (AEM) survey to be flown over the Paterson region of Western Australia. The survey was flown using the TEMPEST AEM system during 2007 and 2008. The data acquisition and data processing and reductions were carried out by Fugro Airborne Surveys (FAS) under contract to Geoscience Australia. The 2010 data release includes the entire Paterson Survey area. This data set includes the eight blocks of infill flying that were completed with funding provided by private companies. The Paterson Survey area is shown on the locality map below (Figure 1). The digital dataset has been arranged into two separate directories or folders according to the two main survey areas Paterson North and Paterson South. Four sub-directories are arranged according to the four main data types which are: (i) Survey operations and processing report, (ii) Point located electromagnetic response and derived EM Flow CDI line data, (iii) Gridded electromagnetic response and CDI data, and (iv) Graphic profile based multiplots showing electromagnetic, CDI and ancillary data.
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Borehole induction conductivity data, commonly referred to as conductivity logs, were acquired from 20 boreholes in the Frome region of South Australia, during July-August 2010, in support of the Frome airborne electromagnetic (AEM) survey managed by Geoscience Australia (GA). The conductivity logs were used to assist in generating reference models for geophysical inversions of the AEM data, and to provide an independent dataset for assessing the inversion results. The Frome AEM survey was acquired using the Fugro Airborne Surveys (FAS) TEMPEST fixed wing time-domain electromagnetic (TEM) AEM system. The acquisition and processing of data were carried out by FAS under contract to GA. The geophysical investigations were designed to deliver reliable, pre-competitive AEM data and scientific analysis of the energy resource potential of the Frome region of South Australia, including the flanks of the Northern Flinders Ranges, the Frome Embayment, the Olary Ranges and the northwestern Murray Basin. The Frome AEM survey covers a total area of 95,000 km2 and was flown between 22 May and 2 November 2010.
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This report describes the geophysical inversion of the Honeysuckle Creek TEMPEST airborne electromagnetic (AEM) survey data (Geoscience Australia Airborne Geophysics Project # 903) to produce subsurface electrical conductivity predictions using a layered earth inversion algorithm developed by Geoscience Australia (GA-LEI). It also describes the products that were derived from the GA-LEI subsurface electrical conductivity predictions. The GA-LEI algorithm has significantly improved on previous conductivity predictions generated by inversion and conductivity depth transform methods, as shown by comparisons between conductivity predictions and ground truth data (measurements of conductivity acquired down boreholes). While this comparison is best shown graphically, statistically speaking the correlation between the GA-LEI predictions and borehole measured conductivities (R2 = 0.77) is better than for previous predictions from inversions (R2 = 0.05 and 0.47), and conductivity depth transforms (R2 = 0.04 and 0.47). This improvement is attributed to the GA-LEI methodology, which solved for three unmeasured components of the system geometry as well as the ground conductivity model, and was guided by downhole conductivity and geological knowledge. In addition, the GA-LEI method used both the X and Z components of the measured response, and used minimally processed data which have fewer introduced assumptions than data previously used. Being an inversion, it compared the calculated response from the subsurface conductivity predictions with the measured response data, ensuring the conductivity predictions results are consistent with measured data, which was not done with previous transform methods. The subsurface electrical conductivity predictions produced by the GA-LEI were post-processed to produce a variety of derivative products. These products were designed to be used without specialised geophysical knowledge, however, they should only be considered depictions of the data, and the methods used in their generation have instilled their own biases. The main products derived from the GA-LEI results are: layer conductivities; conductivity depth slices; vertical conductivity sections; a conductance distribution; and, an estimate of the depth of the basement rocks beneath the regolith. These products have been enhanced, producing colour images stored in either the JPEG or PDF format. All products are available from the Geoscience Australia website (www.ga.gov.au).
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This dataset includes products derived from the Honeysuckle Creek airborne electromagnetic (AEM) survey (Geoscience Australia Airborne Geophysics Project number 903), which was acquired in 2001 near Shepparton in Victoria. The derivative products have been specially designed through the application of the Geoscience Australia Layered Earth Inversion (GA-LEI) algorithm, to facilitate easier use than the original data. However, they should only be considered depictions of the data, and the methods used in their generation instil their own biases. The dataset includes the following products derived from the GA-LEI results: - GA-LEI data in a point located or line format (ASCII format). - Vertical conductivity sections (JPEG and PDF format). - Conductance grids (ERMapper format) and images (JPEG format). - Conductivity depth slice grids (ERMapper format) and images (JPEG format). - Layer conductivity grids (ERMapper format). - Depth to basement grids (ERMapper format) and images (JPEG format). - 3-dimensional voxet of conductivity. The whole dataset is stored in 12 ZIP files, and should be referred to as Fisher and Brodie (2008b). For more information on all the files included in the dataset, as well as the methods used in creating the derivative products see Fisher and Brodie (2008a). REFERENCES Fisher, A.G. and Brodie, R.C., 2008a. Geoscience Australia LEI Products from the Honeysuckle Creek TEMPEST AEM survey, Victoria. Geoscience Australia Record 2008/12. Fisher, A.G. and Brodie, R.C., 2008b. Geoscience Australia LEI Products from the Honeysuckle Creek TEMPEST AEM survey, Victoria [Digital Dataset]. Geoscience Australia, Canberra.
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<p>This data package contains three airborne geophysical datasets processed from the Billabong Creek Geophysical survey, southern New South Wales, flown in 2001. The datasets are: a new Geoscience Australia layered earth inversion (GA-LEI) of the Billabong Creek TEMPEST Airborne Electromagnetic (AEM) survey; an airborne magnetic, gamma-ray and elevation (MAGSPEC) survey; and an extract of the Australian National Gravity Database (GRAVITY). The additional processing and enhancement of the 2001 geophysical survey data has significantly improved previous conductivity predictions as well as enabling the extraction of geologically significant information to support salinity and natural resource management. <p>This metadata briefly describes the contents of the data package. The user guide included in the package contains more detailed information about the individual datasets and available technical reports. <p>The AEM dataset comprises the final Geoscience Australia layered earth inversion (GA-LEI) of the 2001 Billabong Creek TEMPEST AEM survey, produced in 2008. The main data products from the GA-LEI inversion are: point located inversion output data; horizontal layer conductivity grids below ground surface; horizontal conductivity-depth slice grids of various regular depth intervals below ground surface; vertical conductivity-depth sections along each flight line; horizontal conductance distribution grids; interpreted grids of the depth and elevation of the base of the conductive unit; and images of the above datasets produced using standard image enhancement techniques. The GA-LEI AEM data are derived from the 'Billabong Creek TEMPEST AEM Survey, NSW, 2001 Final Located Data (P904)', available as Geoscience Australia product number 65385 (GeoCat #65385). The GA-LEI has been demonstrated to generate more accurate conductivity predictions than other algorithms for similar TEMPEST surveys. The MAGSPEC datasets are: airborne magnetic data comprising grids of total magnetic intensity (TMI), TMI reduced to pole (TMI-RTP), TMI-RTP first vertical derivative data and a range of enhanced magnetic images derived from the data; airborne gamma-ray data comprising grids of dose rate, concentration of potassium (K), thorium (Th) and uranium (U) and a range of enhanced gamma-ray images derived from the data; and elevation data comprising grids and images of the digital elevation model (DEM) derived from the MAGSPEC survey. <p>The GRAVITY dataset includes point located data, grids and enhanced images of data extracted from the Australian National Gravity Database. <p>The point located data are stored in ASCII files (.asc) formatted with space-delimited columns with an associated comprehensive header (.hdr) file. The gridded data are stored in ER Mapper and ESRI grid formats as binary raster grid files. The image data are stored in JPG format with associated world (.jgw) files. Technical reports describing the data processing techniques are stored in Portable Document Format (.pdf). The datasets are compressed in ZIP files. <p>The Billabong Creek airborne geophysics survey was commissioned by the Murray-Darling Basin Commission in 2001. Fugro Airborne Surveys Pty Ltd (Fugro) was contracted to acquire and process the AEM survey utilising the TEMPEST time domain airborne electromagnetic system. Kevron Geophysics Pty Ltd (Kevron) was contracted to acquire and process the MAGSPEC survey utilising an industry standard system. The project was administered by the Australian Government Department of Agriculture, Fisheries and Forestry through the Bureau of Rural Sciences (BRS), now known as the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES). Geoscience Australia (GA) managed and quality controlled the work of Kevron and Fugro. Additional processing and enhancements of the 2001 airborne geophysics data was undertaken by GA in 2007-08, with funding from the National Action Plan for Salinity and Water Quality.
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In 2001, the Murray Darling Basin Commission (MDBC) funded a survey to collect airborne electromagnetic (AEM) datasets for Honeysuckle Creek (GA Project # 903) under MDBC's Strategic Investigations and Education (SI&E) Program, as part of Airborne Geophysics - SI&E Project D2018. The project was a pilot testing the relevance of airborne geophysics data for salinity management, and evolved from the National Geophysics Project originally sponsored under the National Dryland Salinity Program. The data are now being publicly released through Geoscience Australia's National Airborne Geophysics Database.
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The Pine Creek AEM survey was flown over the Pine Creek Orogen in the Northern Territory during 2008 and 2009 as part of the Australian Government's Onshore Energy Security Program at Geoscience Australia (GA). The survey covers an area of 74,000 km2 from Darwin to Katherine in the Northern Territory which hosts several world class deposits, including the Ranger Uranium Mine, Nabarlek, Mt Todd, Moline and Cosmo Howley. Aimed at regional mapping, uranium exploration, reducing exploration risk and promoting exploration activity, the program worked closely with industry partners to infill wide regional line spacing (5km) with deposit scale line spacing (less than 1km). The survey results are relevant in exploration for a variety of commodities and resources, including uranium, copper, lead, zinc, gold, nickel and groundwater. Geoscience Australia's interpretation products include sample-by-sample layered earth inversion products comprising located data, geo-located conductivity depth sections, depth slice grids, elevation slice grids, inversion report and an interpretation report. All data and products are available from GA as well as the Northern Territory Geological Survey Geophysical Image Web Server.