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  • 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.

  • The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of Potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This radiometric uranium grid has a cell size of 0.000417 degrees (approximately 40m) and shows uranium element concentration of the Dirranbandi (SE Bollon), Qld, 1981 survey. The data used to produce this grid was acquired in UNKNOWN by the Qld Government, and consisted of 3218 line-kilometres of data at 250m line spacing and 50m terrain clearance.

  • The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of Potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This radiometric uranium grid has a cell size of 0.0006 degrees (approximately 60m) and shows uranium element concentration of the Wudinna, SA, 1986 (86SA02) (74xl) survey. The data used to produce this grid was acquired in 1986 by the SA Government, and consisted of UNKNOWN line-kilometres of data at 300m line spacing and 80m terrain clearance.

  • Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This magnetic grid has a cell size of 0.001 degrees (approximately 100m). The data used to produce this grid was acquired in 1994 by the SA Government, and consisted of 12166 line-kilometres of data at 400m line spacing and 60m terrain clearance.

  • The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of Potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This radiometric uranium grid has a cell size of 0.000614 degrees (approximately 60m) and shows uranium element concentration of the Marulan-Mossvale, NSW, 1998 survey. The data used to produce this grid was acquired in 1998 by the NSW Government, and consisted of 1600 line-kilometres of data at 250m line spacing and 60m terrain clearance.

  • The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of Potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This radiometric uranium grid has a cell size of 0.004 degrees (approximately 430m) and shows uranium element concentration of the Canning Basin (Charnley, Lennard R, Noonkanbah, Crossland), WA, 1989 survey. The data used to produce this grid was acquired in 1989 by the WA Government, and consisted of 51022 line-kilometres of data at 1500m line spacing and 150m terrain clearance.

  • The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This radiometric potassium grid has a cell size of 0.0005 degrees (approximately 50m) and shows potassium element concentration of the Wyena, QLD, 1992 survey. The data used to produce this grid was acquired in 1992 by the Qld Government, and consisted of 2443 line-kilometres of data at 200m line spacing and 60m terrain clearance.

  • The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This radiometric potassium grid has a cell size of 0.000497 degrees (approximately 50m) and shows potassium element concentration of the West Gippsland, Vic, 2001 VIMP Survey (GSV3172) survey. The data used to produce this grid was acquired in 2001 by the VIC Government, and consisted of 67955 line-kilometres of data at 250m line spacing and 80m terrain clearance.

  • The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This radiometric potassium grid has a cell size of 0.00096 degrees (approximately 100m) and shows potassium element concentration of the Drummond & Galilee Qld, (Geomap 2005) GDI 1997/1998 survey. The data used to produce this grid was acquired in 1997 by the QLD Government, and consisted of 198262 line-kilometres of data at 400m line spacing and 80m terrain clearance.