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  • The map addresses the distribution of Archaean rocks of the central Eastern Goldfields of Western Australia. Interpretation was undertaken at 1:250 000 scale for both Geoscience Australia aeromagnetic data (400m linespacing) and Fugro Airborne Surveys Pty. Ltd. data (200m linespacing). The Archaean rocks are subdivided into undivided gneiss-migmatite-granite (Agmg), banded gneiss (Agn), greenstone (Aa), and granite plutons (Ag). Where important relative differences in magnetisation are mapped, the geophysical map units include the suffixes _h (high), _m (medium), _l (low) and _r (remanent) for the level of magnetisation. Dykes, faults, and unassigned small intrusives are also mapped. The map is derived from a subset of a more extensive interpretation covering the exposed extent of the Yilgarn Craton.

  • This map is designed to show broad regolith-landform units, giving a regional overview of the main regolith types and their associated landforms.Included are the author's detailed Explanatory Notes to the map.

  • This map is designed to show broad regolith-landform units, giving a regional overview of the main regolith types and their associated landforms.Included are the author's detailed Explanatory Notes to the map.

  • <p>The Murray Basin extends over 300 000 km of inland southeastern Australia, is flanked by subdued mountain ranges, and forms a low-lying saucer-shaped basin with thin flat-lying Cainozoic sediments. Over the past 100 years, the Murray Basin has become one of the most important agricultural regions in Australia. Unfortunately it is also a closed groundwater basin, which consists of a thin sequence of sediments containing a number of aquifer systems, with little capacity to absorb additional recharge. Irrigation and clearing of natural vegetation have increased recharge to these aquifer systems. Resultant rising groundwater levels and discharge of saline water into the landscapes and river systems of the basin, have created salinity problems that threaten to have an increasingly adverse impact on both the regional economy and natural environments. Many of the reasons for salinisation lie in the subsurface geology, and can be related to the development of the structural and stratigraphic framework of the basin over the past 60 Ma. Knowledge of these is a prerequisite to understanding hydrogeological systems and processes contributing to the salinity problem. This document summarises the geology of the Murray Basin. <p>Beneath the Murray Basin, geophysical and borehole evidence indicates that folded and partly metamorphosed Proterozoic and Lower Palaeozoic basement is block-faulted, and that the Cainozoic sequence is locally underlain by poorly defined infrabasins preserved in graben-like troughs. These contain thick sequences of Devonian to Lower Carboniferous sedimentary rock and discontinuous, erosional remnants of Upper Carboniferous, Permian, Triassic and Cretaceous platform-cover sediments. <p>The Cainozoic succession of the Murray Basin forms an extensive blanket of sediment, with a maximum thickness of about 600 m preserved in the deeper, central-western parts of the basin. A subsidiary depocentre with over 400 m of sediment underlies the central-west Riverine Plain, but in most northern, eastern, and southern parts of the basin the sediment succession is generally less than 200-300 m thick, and could be more accurately described as forming a thin platform-cover succession rather than a true basinal sequence. Within the Tertiary succession at least three major depositional sequences (Paleocene Eocene to Lower Oligocene, Oligocene Middle Miocene, and Upper Miocene Pliocene) have been identified. Each sequence consists of a package of genetically related formations separated by disconformities. Poorly consolidated, non-marine sand, silt, clay, and carbonaceous sedimentary rocks predominate in the east and north, but each of the depositional sequences includes weakly lithified marine sedimentary rocks in central and southwestern areas. The stratigraphy translates into a number of regional aquifer systems, confining layers and permeability barriers to groundwater flow, each with distinctive characteristics. <p>In the Mallee region of the west, the Tertiary sediments of the Murray Basin are almost entirely concealed beneath a mainly fossil' arid and semi-arid landscape of Quaternary aeolian dunefields, with minor fluvial and lacustrine morphostratigraphic units. Farther east, where the basin and adjacent highlands are drained by the Murray, Murrumbidgee and Lachlan Rivers, the Tertiary sequence underlies flat-lying fluvio-lacustrine and minor aeolian sediments of the semi-arid landscape of the Riverine Plain. Within the Mallee and Riverine Plain landscapes, active and fossiV (currently inactive) groundwater discharge lake complexes can be identified by characteristic assemblages of Upper Quaternary sediments forming stranded lake floors, gypsum flats, salinas, gypsum and clay pellet dunes and lunettes. These have developed within low-lying areas during the past 0.5 Ma. Their extent indicates the presence of widespread salinisation under 'natural9 conditions at times in the recent geologic past. <p>The main emphasis of the study is on improving our understanding of the geological context of groundwater and surface discharge in the Murray Basin, but at an early stage the scope of the study was expanded to include reference to other mineral resources. These include Cainozoic limestone, alluvial gold, kaolin, heavy minerals, gypsum and halite deposits. The Tertiary succession contains extensive deposits of currently sub-economic brown coal, underlain by Upper Permian coal in the Oaklands Infrabasin in New South Wales. The Cainozoic Murray Basin is not prospective for hydrocarbons, but several concealed pre-Cainozoic infrabasins remain poorly investigated.

  • The map of iron oxide copper-gold (IOCG) potential of the Gawler Craton, South Australia, shows the spatial distribution of key 'essential ingredients' of IOCG ore-forming systems. These 'ingredients' include: (a) rock units of the Gawler Range-Hiltaba Volcano-Plutonic Association, subdivided by supersuite; (b) faults/shear zones subdivided by interpreted age of youngest significant movement; (c) copper geochemistry (>200ppm), from drill holes intersecting crystalline basement (Mesoproterozoic and older); (d) hydrothermal alteration assemblages and zones, based on drill hole logging, potential-field interpretation, and inversion modelling of potential-field data; and (e) host sequence units considered important in localising IOCG alteration and mineralisation. Also shown are Nd isotopic data and the mineral isotopic ages of late Palaeoproterozoic to early Mesoproterozoic magmatism and hydrothermal minerals. Areas with the greatest number of 'essential ingredients' are considered to have the maximum potential for IOCG mineralisation. IOCG potential of the Gawler Craton is shown as domains with ranks from 1 to 4, with 1 being the highest rank. Notes detailing the sources of data and methods used in constructing the map are provided in a separate file available on the Geoscience Australia website.

  • Total Magnetic Intensity (TMI) Colour Composite Image of Australia with Variable Reduction to Pole (VRTP) 2015 The file is an image created from magmap_v6_2015_VRTP a Variable Reduction to Pole TMI grid of the Australian region with a grid cell spacing of ~3 seconds of arc (approximately 80 m). This image only includes airborne-derived TMI data for onshore and near-offshore continental areas. Matching of the grids for the 6th Edition TMI anomaly grid of Australia was achieved using a program called Gridmerge, which was originally developed within Geoscience Australia and has now been commercialised. This program was used to merge 41 new surveys to the 5th Edition Total Magnetic Intensity Anomaly Grid of Australia (Milligan et al., 2010). The 5th Edition merged 795 individual grids to create the compilation and to constrain long wavelengths, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of those survey grids which overlapped the AWAGS data (Milligan et al., 2009). As the 5th Edition was used as a base grid for the Gridmerge operation the new 6th Edition is essentially levelled to AWAGS. Details of the specifications of individual airborne surveys can be found in the Fourteenth Edition of the Index of Airborne Geophysical Surveys (Percival, 2014), which is included with the grid as a PDF document called magmap_V6_2015.pdf. This Index is also available online at http://pid.geoscience.gov.au/dataset/ga/79134. Further up to date information about individual surveys can also be obtained online from the Airborne Surveys Database at http://www.ga.gov.au/oracle/argus/. The VRTP processing followed Cooper and Cowan's (2005) differential reduction to pole up to 5th order polynomial. Magnetic inclination and declination were derived from the IGRF-11 geomagnetic reference model (Finlay et al., 2010) using a data representative date of January 2005 and elevation 300 m. Grid downloads: The VRTP Magnetic Map of Australia grid can be downloaded using the Geophysical Archive Data Delivery System (GADDS) on the Australian Government's Geoscience Portal at http://www.geoscience.gov.au/gadds File size: At full resolution, the VRTP Magnetic Map of Australia grid has 41882 rows and 50591 columns and has a file size of approximately 8.3 Gb in ERMapper format. Note that, because of GADDS file size limits, it is not possible for clients to download very large areas of the grid at full resolution. Clients wishing to do so should contact Geoscience Australia to make special arrangements to have the complete grid dataset provided on a user-supplied portable hard drive. Milligan, P.R., Franklin, R., Minty, B.R.S., Richardson, L.M. and Percival, P.J., 2010. Magnetic Anomaly Map of Australia (Fifth Edition), 1:5 000 000 scale, Geoscience Australia, Canberra. Percival, P.J., 2014. Index of airborne geophysical surveys (Fourteenth Edition). Geoscience Australia Record 2014/014.

  • Filtered Dose - Terrestrial dose rate derived as a linear combination of the filtered K, U and Th grids described in Minty et al. (2009), units: nG/h The Radiometric Map of Australia dataset comprises grids of potassium (K), uranium (U) and thorium (Th) element concentrations, and derivatives of these grids. The third edition was derived by seamlessly merging 45 new survey grids with the Second Edition Radiometric Map of Australia (Minty et al., 2010). Details of the specifications of individual airborne surveys can be found in the Fourteenth Edition of the Index of Airborne Geophysical Surveys (Percival, 2014), which is included with the grid as a PDF document. This Index is also available online at http://pid.geoscience.gov.au/dataset/ga/79134. Further up to date information about individual surveys can also be obtained online from the Airborne Surveys Database at http://www.ga.gov.au/oracle/argus/. Matching of the grids in the database was achieved using a program called Gridmerge, which was originally developed within Geoscience Australia and has now been commercialised. This program was used to merge 45 new surveys to the Second Edition Radiometric Map of Australia. The second edition merged over 550 individual grids to create the compilation (Minty et al., 2009) and the Australia-wide Airborne Geophysical Survey (AWAGS) airborne radiometric data was used to control the base levels of those survey grids which overlapped the AWAGS data (Milligan et al., 2009). As the second edition was used as a base grid for the Gridmerge operation the new Third Edition is essentially levelled to AWAGS. Cell sizes: The cell sizes of the original survey grids range from 50 m through 800 m, but most have a cell size of about 100 m. The 45 original survey grids were levelled and then re-sampled, using Newton 4th Order local operator onto the Second Edition Radiometric Map of Australia Grids with a cell size of about 100m (0.001 degrees). Filtering: Potassium, uranium, thorium and dose rate grid are available in both filtered and unfiltered versions. The low-pass filtering was achieved by applying a 7-point, degree-3 Savitzky-Golay filter (Savitzky & Golay, 1964) to each of the original survey grids prior to grid merging. Projections and Datums: The grids are stored as geodetic grids based on the GDA94 datum, but can be re-projected prior to downloading. Grid downloads: The Radiometric Map of Australia grids can be downloaded using the Geophysical Archive Data Delivery System (GADDS) on the Australian Government's Geoscience Portal at http://www.geoscience.gov.au/gadds File sizes: At full resolution, each Radiometric Map of Australia grid has 34761 rows and 40954 columns. Each grid has a file size of approximately 5.3 Gb in ERMapper format. Note that, because of the file sizes, GADDS will not allow users to do download the grids at full resolution. Users wishing to access the grids at full resolution should contact Geoscience Australia to make arrangements to have the data supplied on a portable hard drive.

  • Ratio U2/Th - Ratio of U2 over Th derived from the filtered U and Th grids, units: dimensionless The Radiometric Map of Australia dataset comprises grids of potassium (K), uranium (U) and thorium (Th) element concentrations, and derivatives of these grids. The third edition was derived by seamlessly merging 45 new survey grids with the Second Edition Radiometric Map of Australia (Minty et al., 2010). Details of the specifications of individual airborne surveys can be found in the Fourteenth Edition of the Index of Airborne Geophysical Surveys (Percival, 2014), which is included with the grid as a PDF document. This Index is also available online at http://pid.geoscience.gov.au/dataset/ga/79134. Further up to date information about individual surveys can also be obtained online from the Airborne Surveys Database at http://www.ga.gov.au/oracle/argus/. Matching of the grids in the database was achieved using a program called Gridmerge, which was originally developed within Geoscience Australia and has now been commercialised. This program was used to merge 45 new surveys to the Second Edition Radiometric Map of Australia. The second edition merged over 550 individual grids to create the compilation (Minty et al., 2009) and the Australia-wide Airborne Geophysical Survey (AWAGS) airborne radiometric data was used to control the base levels of those survey grids which overlapped the AWAGS data (Milligan et al., 2009). As the second edition was used as a base grid for the Gridmerge operation the new Third Edition is essentially levelled to AWAGS. Cell sizes: The cell sizes of the original survey grids range from 50 m through 800 m, but most have a cell size of about 100 m. The 45 original survey grids were levelled and then re-sampled, using Newton 4th Order local operator onto the Second Edition Radiometric Map of Australia Grids with a cell size of about 100m (0.001 degrees). Filtering: Potassium, uranium, thorium and dose rate grid are available in both filtered and unfiltered versions. The low-pass filtering was achieved by applying a 7-point, degree-3 Savitzky-Golay filter (Savitzky & Golay, 1964) to each of the original survey grids prior to grid merging. Projections and Datums: The grids are stored as geodetic grids based on the GDA94 datum, but can be re-projected prior to downloading. Grid downloads: The Radiometric Map of Australia grids can be downloaded using the Geophysical Archive Data Delivery System (GADDS) on the Australian Government's Geoscience Portal at http://www.geoscience.gov.au/gadds File sizes: At full resolution, each Radiometric Map of Australia grid has 34761 rows and 40954 columns. Each grid has a file size of approximately 5.3 Gb in ERMapper format. Note that, because of the file sizes, GADDS will not allow users to do download the grids at full resolution. Users wishing to access the grids at full resolution should contact Geoscience Australia to make arrangements to have the data supplied on a portable hard drive.

  • Ratio of U over K derived from the filtered U and K grids, units: dimensionless The Radiometric Map of Australia dataset comprises grids of potassium (K), uranium (U) and thorium (Th) element concentrations, and derivatives of these grids. The third edition was derived by seamlessly merging 45 new survey grids with the Second Edition Radiometric Map of Australia (Minty et al., 2010). Details of the specifications of individual airborne surveys can be found in the Fourteenth Edition of the Index of Airborne Geophysical Surveys (Percival, 2014), which is included with the grid as a PDF document. This Index is also available online at http://pid.geoscience.gov.au/dataset/ga/79134. Further up to date information about individual surveys can also be obtained online from the Airborne Surveys Database at http://www.ga.gov.au/oracle/argus/. Matching of the grids in the database was achieved using a program called Gridmerge, which was originally developed within Geoscience Australia and has now been commercialised. This program was used to merge 45 new surveys to the Second Edition Radiometric Map of Australia. The second edition merged over 550 individual grids to create the compilation (Minty et al., 2009) and the Australia-wide Airborne Geophysical Survey (AWAGS) airborne radiometric data was used to control the base levels of those survey grids which overlapped the AWAGS data (Milligan et al., 2009). As the second edition was used as a base grid for the Gridmerge operation the new Third Edition is essentially levelled to AWAGS. Cell sizes: The cell sizes of the original survey grids range from 50 m through 800 m, but most have a cell size of about 100 m. The 45 original survey grids were levelled and then re-sampled, using Newton 4th Order local operator onto the Second Edition Radiometric Map of Australia Grids with a cell size of about 100m (0.001 degrees). Filtering: Potassium, uranium, thorium and dose rate grid are available in both filtered and unfiltered versions. The low-pass filtering was achieved by applying a 7-point, degree-3 Savitzky-Golay filter (Savitzky & Golay, 1964) to each of the original survey grids prior to grid merging. Projections and Datums: The grids are stored as geodetic grids based on the GDA94 datum, but can be re-projected prior to downloading. Grid downloads: The Radiometric Map of Australia grids can be downloaded using the Geophysical Archive Data Delivery System (GADDS) on the Australian Government's Geoscience Portal at http://www.geoscience.gov.au/gadds File sizes: At full resolution, each Radiometric Map of Australia grid has 34761 rows and 40954 columns. Each grid has a file size of approximately 5.3 Gb in ERMapper format. Note that, because of the file sizes, GADDS will not allow users to do download the grids at full resolution. Users wishing to access the grids at full resolution should contact Geoscience Australia to make arrangements to have the data supplied on a portable hard drive.

  • Ratio Th/K - Ratio of Th over K derived from the filtered Th and K grids, units: dimensionless The Radiometric Map of Australia dataset comprises grids of potassium (K), uranium (U) and thorium (Th) element concentrations, and derivatives of these grids. The third edition was derived by seamlessly merging 45 new survey grids with the Second Edition Radiometric Map of Australia (Minty et al., 2010). Details of the specifications of individual airborne surveys can be found in the Fourteenth Edition of the Index of Airborne Geophysical Surveys (Percival, 2014), which is included with the grid as a PDF document. This Index is also available online at http://pid.geoscience.gov.au/dataset/ga/79134. Further up to date information about individual surveys can also be obtained online from the Airborne Surveys Database at http://www.ga.gov.au/oracle/argus/. Matching of the grids in the database was achieved using a program called Gridmerge, which was originally developed within Geoscience Australia and has now been commercialised. This program was used to merge 45 new surveys to the Second Edition Radiometric Map of Australia. The second edition merged over 550 individual grids to create the compilation (Minty et al., 2009) and the Australia-wide Airborne Geophysical Survey (AWAGS) airborne radiometric data was used to control the base levels of those survey grids which overlapped the AWAGS data (Milligan et al., 2009). As the second edition was used as a base grid for the Gridmerge operation the new Third Edition is essentially levelled to AWAGS. Cell sizes: The cell sizes of the original survey grids range from 50 m through 800 m, but most have a cell size of about 100 m. The 45 original survey grids were levelled and then re-sampled, using Newton 4th Order local operator onto the Second Edition Radiometric Map of Australia Grids with a cell size of about 100m (0.001 degrees). Filtering: Potassium, uranium, thorium and dose rate grid are available in both filtered and unfiltered versions. The low-pass filtering was achieved by applying a 7-point, degree-3 Savitzky-Golay filter (Savitzky & Golay, 1964) to each of the original survey grids prior to grid merging. Projections and Datums: The grids are stored as geodetic grids based on the GDA94 datum, but can be re-projected prior to downloading. Grid downloads: The Radiometric Map of Australia grids can be downloaded using the Geophysical Archive Data Delivery System (GADDS) on the Australian Government's Geoscience Portal at http://www.geoscience.gov.au/gadds File sizes: At full resolution, each Radiometric Map of Australia grid has 34761 rows and 40954 columns. Each grid has a file size of approximately 5.3 Gb in ERMapper format. Note that, because of the file sizes, GADDS will not allow users to do download the grids at full resolution. Users wishing to access the grids at full resolution should contact Geoscience Australia to make arrangements to have the data supplied on a portable hard drive.