Legacy product - no abstract available

No abstract available

The Radiometric Map of Australia shows the distribution of potassium (% K), uranium (ppm eU) and thorium (ppm eTh) over Australia. A suite of image enhancement and data integration techniques can be used to enhance the value of these data for both mineral exploration and environmental mapping. Gradient-enhanced ternary and pseudo-colour image enhancements are now routinely used for the presentation and interpretation of gridded radioelement data. Where digital elevation data are available, these colour representations can be draped over the elevation data to form 3D perspective views, or hill-shaded derivatives of the DEM can be embedded into the ternary imagery as an intensity component. These are useful because the radioelement response can then be interpreted within the context of the relative position of anomalous features in the landscape. However, subtle variations in the concentrations of K, U, and Th are best interpreted using the ratios of the radioelements. The U/Th and U2/Th ratios are important indicators of uranium mineralization. The Th/K ratio is widely used for the detection of several styles of mineralization associated with K alteration. For the interpretation of map data, classification and clustering methods can be used to assist pattern recognition and are useful for the rapid assessment of large multivariate datasets. Automatic edge detection procedures can be used to speed up the annotation of unit boundaries. Residual modelling techniques can be used to highlight potential anomalies in the data.

After 60 years of aeromagnetic surveying across Australia, Geoscience Australia is now the custodian of a unique publicly-available continental-scale airborne magnetic database. Using the Magnetic Anomaly Grid Database of Australia (MAGDA), composite grids and image maps can be generated at a variety of resolutions to suit many purposes, ranging from broad continental interpretations to investigations of small, detailed prospective areas. Intermediate wavelengths (100 km to 400 km) in composite grids have significant errors due to the lack of control available during merging. Control lines of the AWAGS (Australia-wide Array of Geomagnetic Stations) survey flown in 1990 have significantly improved the intermediate wavelengths, and a new AWAGS2 (Australia-wide Airborne Geophysical Survey) project, as part of a new Australian Government energy initiative, is currently acquiring new baseline gamma-ray spectrometric and magnetic calibration data with a 75 km line spacing and an 80 m terrain clearance. Standard derivative products are easily generated from the MAGDA database, and current interpretation research is focussed on generation of accurate depths-to-basement of interpretations of prospective areas, better definition of sedimentary basins for petroleum prospectivity evaluation, and interpreted depths to the bottom of magnetic sources in attempts to define the Curie point isotherm. Potential field data also provide important constraints for three-dimensional geological modelling; initial 3D geological models are simultaneously inverted for the secondary variables of mass density and magnetic susceptibility.

The Australian Geological Survey Organisation (AGSO) flew an airborne geophysical survey of 45 459 line km covering the northern part of the Wangaratta 1:250 000 map Sheet area with an extension west onto the Shepparton 1:250 000 Sheet area. This survey formed part of the National Geoscience Mapping Accord and was jointly funded by AGSO and the Geological Survey of Victoria. The remainder of the Wangaratta 1:250 000 map Sheet area was flown under contract for the Geological Survey of Victoria. The AGSO flown survey, (Wangaratta North) was flown along east-west flight lines 200 metres apart at an altitude of 80 metres above ground level. The survey was flown from March to May 1997. The total magnetic intensity, gamma-ray spectrometric and digital elevation model data collected during the survey, have been processed and are available for purchase. These data are sold as digital point located data, grids and hardcopy maps, by the Australian Geological Survey Organisation. Colour and greyscale pixel image maps are also available.

The Australian Geological Survey Organisation (AGSO) flew an airborne geophysical survey of 69 086 line km covering the entire Cootamundra 1:250 000 map Sheet area in the Lachlan Fold Belt of New South Wales. The survey formed part of the National Geoscience Mapping Accord and was jointly funded by AGSO, Department of Primary Industries and Energy and the Geological Survey, New South Wales Department of Mineral Resources. The survey was flown along east-west flight lines, 250 metres apart at an altitude of 80 metres above ground level. AGSO flew the survey over two periods; from November to December 1997 and from February to March 1998. The total magnetic intensity, gamma-ray spectrometric and digital elevation model data collected during the survey, have been processed and are available for purchase. These data are sold as digital point located data, grids and hardcopy maps, by the Australian Geological Survey Organisation. Colour and greyscale pixel image maps are also available.

Legacy product - no abstract available

22-2/F54-3/6-18 Contour interval = 0.5

22-2/F54-3/1-18 Contour interval = 0.5

No abstract available