Catchment outlet sediments (0-10 cm depth, sieved to <2 mm) collected at a very low density over most of the Australian continent have been analysed using the Mobile Metal Ion (MMI®) partial extraction technique. Of the 54 elements analysed, eight are generally regarded as essential nutrients for plant growth: Ca, Cu, Fe, K, Mg, Mn, P and Zn. For these, 'bioavailability', defined here as the ratio of the partial digest concentration to the total concentration, has been investigated. This estimation of 'bioavailability' gives results comparable with standard agricultural measurements. Average 'bioavailability' ranges from 15.0% for Ca to 0.1% for Fe. Smoothed (kriged) colour contour maps for continental Australia have been produced for these eight nutrients and interpreted in terms of lithology (e.g., presence of carbonates in the MMI® Ca map), mineralization (e.g., well known and possibly less known mineral districts in the Cu, P and Zn maps), environmental processes (e.g., salinity in K map, weathering and acid generation in Fe map) and agricultural practices (e.g., application of fertilizers in P and Zn maps). This first application of a partial extraction technique at the scale of a continent has yielded meaningful, coherent and interpretable results.

The 1:250 000 maps show the type and distribution of 51 regolith-landform units with unique dominant regolith-landform associations, and are a subset of the 205 mapping units on the six 1:100 000 maps. These units are distinct patterns of recurring landform elements with characteristic regolith associations. Geomorphic symbols indicate the location and type of geomorphic activity. The maps present a systematic analysis and interpretation of 1:89 000 scale 1973 RC9 aerial photography, 1:100 000 scale topographic maps (AUSLIG), and field mapping data. High resolution (250m line spacing) airborne gamma-ray spectrometry and magnetics (Geoterrex) were used where applicable

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Many countries around the world have carried out national-scale geochemical surveys, providing important information on the natural concentration of chemical elements and compounds in the near-surface regolith. Resultant data and information layers have been put to a multitude of uses: Identifying targets for mineral exploration; improving land-use management and environmental policy development; and providing information for studies into the health and well-being of humans, animals and plants. Between 2003 and 2007 several regional geochemical pilot surveys were conducted in Australia. These surveys have identified element concentrations that relate to soil acidity and salinity, reflect known areas of mineralisation, or are above or below national and international agricultural soils guidelines. In 2007, following on from the success of the pilot surveys, Geoscience Australia established Australia's first national geochemical survey. Working in collaboration with State and Territory geoscience agencies, ultra low-density sampling of catchment outlet (overbank) sediments from two depths (0-10 cm below surface and from a 10 cm interval at around 60-90 cm) has commenced. Samples are prepared and split into <2 mm and <75 mm fractions before both are analysed using a wide range of analytical techniques including XRF and ICP-MS. To date, 80% of samples have been collected and 50% of the total number of samples have been analysed. Ultimately the National Geochemical Survey of Australia project will rapidly and cost-effectively deliver a national geochemical atlas and a new dataset that will underpin positive outcomes in the exploration and mining, environmental, agricultural, forestry, recreational, and health and well-being sectors.

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Legacy product - no abstract available

Legacy product - no abstract available

In late 2006, the Australian Government announced its Energy Security Initiative, allowing Geoscience Australia to initiate a major program of onshore and offshore activities. The ambitious National Geochemical Survey of Australia (NGSA) project was launched in January 2007 as part of this program because until then Australia lacked a complete geochemical data coverage. Such a dataset informs on the concentrations and distributions of chemical elements in the near-surface environment. This pre-competitive knowledge, used in combination with other datasets, can contribute to making exploration for energy and mineral resources more cost-effective and less risky by helping target more detailed activities. As a spin-off, the multi-element dataset can also have applications in the fields of natural resources management, land-use decision-making and geohealth, for instance. During precursor pilot projects carried out between 2003 and 2006 in the Riverina, Gawler and Thomson regions, various sampling media, grain-size fractions and analytical methods were tested. In particular, it emerged that catchment outlet sediments from either overbank or floodplain settings or from similar low-lying settings were an ideal sampling medium that could be found across Australia. These sediments are, by their very nature, well-mixed composites of contributions from the dominant rock and soil types found within a catchment. Further, being deposited during times of receding floods, they are typically fine-grained, a beneficial property that enhances the geochemical signal-to-noise ratio. The data from the pilot projects indicated that even surface catchment outlet sediments could reflect geochemical signatures from basement and mineralisation, even when covered by thick transported overburden. .../...

No abstract available

The Southern Thomson Orogen VTEMplus® AEM Survey was undertaken as part of Geoscience Australia's contribution to the Australian Academy of Science's UNCOVER initiative, adopted as part of the Australian Government's National Mineral Exploration Strategy. Survey planning was in conjunction with our State survey partners, the Geological Survey of New South Wales and the Geological Survey of Queensland. The aim of the survey was to demonstrate the application of the AEM technique as an under-cover mapping and exploration tool by generating new data and information regarding depth to basement (DTB) and cover character in the under-explored southern Thomson Orogen region. The ultimate goal of the Southern Thomson Project is to encourage industry investment in this poorly understood area to discover a new minerals province.