Displays the coverage of publicly available digital aeromagnetic data. The map legend is coloured according to the line spacing of the survey with broader line spacings (lower resolution surveys) displayed in shades of blue. Closer line spacings (higher resolution surveys are displayed in red, purple and coral.

Legacy product - no abstract available

Three seismic lines (10GA-CP1, 10GA-CP2 and 10GA-CP3), which cross north to south across the Capricorn Orogen of Western Australia, have recently been collected by Geoscience Australia, ANSIR and the Geological Survey of Western Australia. The interpretation of these seismic lines is aimed at providing insight into the geologic structure of the Capricorn Orogen and to explore the relationship between the Pilbara and Yilgarn cratons. To aid in further interpretation and to add value to the seismic data an analysis of the available potential field data (gravity and magnetics) has also been undertaken. A range of geophysical data analysis techniques have been applied and include: multi-scale edge detection (worms), forward modelling and 3D inversion. By applying all three analysis techniques to the potential-field data major trends, contrasting properties and regional blocks relating to the subsurface geology have been determined, in turn, allowing for a detailed comparison with the seismic interpretation. Note that all results referred to in this abstract are preliminary and subject to change.

No abstract available

Predictive maps of the subsurface can be generated when geophysical datasets are modelled in 2D and 3D using available geological knowledge. Inversion is a process that identifies candidate models which explain an observed dataset. Gravity, magnetic, and electromagnetic datasets can now be inverted routinely to derive plausible density, magnetic susceptibility, or conductivity models of the subsurface. The biggest challenge for such modelling is that any geophysical dataset may result from an infinite number of mathematically-plausible models, however, only a very small number of those models are also geologically plausible. It is critical to include all available geological knowledge in the inversion process to ensure only geologically plausible physical property models are recovered. Once a set of reasonable physical property models are obtained, knowledge of the physical properties of the expected rocks and minerals can be used to classify the recovered physical models into predictive lithological and mineralogical models. These predicted 2D and 3D maps can be generated at any scale, for Government-funded precompetitive mapping or drilling targets delineation for explorers.

Legacy product - no abstract available

Legacy product - no abstract available

The Australian Geological Survey Organistaion (AGSO) has produced a set of digital bathymetry, gravity and magnetic grids for the southwest quadrant of Australia (24 - 46S, 106-140E), using all available land, marine and satellite data. The work was done in cooperation with Desmond Fitzgerald & Associates (DFA), and with significant bathymetric data input from the Australian Hydrographic Office (AHO). The results were obtained by performing a network adjustment on marine ship-track data, and combining these with onshore and satellite-derived data.

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.

The North Pilbara project's main objective is to assist industry in their development off exploration strategies. In order to do this, we provide high-quality data sets such as this GIS, which provides different views of the same area, allowing correlation, comparison, and analysis at a broad scale across the entire North Pilbara. The advantage of this GIS is that it packages Geoscience Australia's primary data holdings for the entire region into a convenient digital package that can be manipulated and integrated with proprietary data in standard mapping applications. The North Pilbara GIS provides industry with a decision-making context, or wide-spaced framework. The lack of context is due the fact that industry commonly only have restricted data holdings over their leases. Therefore, regional synthesis data sets provide a context and framework for exploration decisions made on more spatially limited data. The North Pilbara GIS provides many new digital data sets, including a number of variations of the magnetics, gravity, and gamma-ray spectrometry. A solid geology map, and derivative maps, mineral deposits, geological events, and Landsat 5-TM provide additional views. This data set complements the 1:1.5 Million scale colour atlas (announced in June-July issue 58 of AusGeoNews). This provision of a regional digital data set will be an invaluable tool for exploration companies making comparative, correlative, and analytical decisions on the prospectivity of the North Pilbara. Just a few of the new aspects of the GIS include: <ul> <li>the under cover shape of prospective rocks with a new digital solid geology map;</li> <li>all the images generated by the project (magnetics, gravity, Landsat, and radiometrics);</li> <li>the imaging of several large shear zones, and complexity in granites;</li> <li>compilation of geochemistry and geochronology;</li> <li>a new chemical map based on radiometrics;</li> <li>identification of the source regions of transported regolith</li> </ul> This map has been produced as a GeoPDF, which is an extension to the standard PDF file format viewed using Adobe Acrobat Reader. Layers can be turned off and on to customise the view of the data, similar to using Geographic Information System tools. In addition, GeoPDF maps are georeferenced to be compatible with other coordinated geographic data. Coordinate locations and distances can be retrieved automatically. A plug-in to view GeoPDF using Adobe Acrobat Reader is available as a free download ( http://terragotech.com/solutions/map2pdf_reader.php ).