AusGeo News March 2013 Issue No. 109
Datasets from three new geophysical surveys have been released since December 2012.
Table 1: Airborne Magnetic—Radiometric—Elevation Surveys.
|Survey||Date||1:250 000 Map Sheets||Line Spacing (m), terrain clearance (m), orientation||Line Km||Contractor|
|Perth Basin South||March 2011–July 2012||Dongara (pt),
Hill River (pt),
east – west
|88 000||Fugro Airborne Surveys Pty Ltd|
|South West 3 (Cape Leeuwin)||March 2011–January 2012||Busselton (pt),
east – west
|28 050||Fugro Airborne Surveys Pty Ltd|
|Grafton– Tenterfield||June 2011–December 2012||Goondiwindi (pt),
Tweed Heads (pt),
|P Regent, Montague:
|100 000||GPX Surveys Pty Ltd|
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Geoscience Australia has released a new multibeam bathymetry dataset that provides improved visualisation of the topography and nature of the seafloor of offshore Australia.
Bathymetry is the measurement or mapping of seafloor topography. One of the most accurate ways of collecting bathymetry data is through the use of multibeam echosounders which are acoustic ship-bourne instruments designed to map the ocean floor.
Geoscience Australia is the national custodian of an extensive multibeam dataset. The 50 metre Multibeam Dataset of Australia 2012 is a tiled compilation of the entire multibeam dataset held by Geoscience Australia, including all data lying within the outer edge of the offshore area of Australia, as well as some data in international waters. Some of the multibeam data was collected by Geoscience Australia with the remaining data having been submitted by other institutions in the international scientific community.
Several formats are provided for download (projected in WGS84 UTM zones) including:
This dataset is available to download as individual tiles from the Geoscience Australia website, or the entire 50 m Multibeam Dataset of Australia 2012 is available on a hard drive and can be purchased from the Geoscience Australia Sales Centre, for a cost of $55 (please quote GeoCAT number 73842).
A map of palaeovalleys across the arid and semi-arid zones of Western Australia (WA), South Australia (SA) and the Northern Territory (NT), the 'WASANT Palaeovalley Map', is now available for download from Geoscience Australia's website. It provides a synoptic view of the distribution and disposition of ancient valley networks across the continent and is aimed at providing guidance for more locally focussed investigations for groundwater resources within palaeovalley aquifers.
The map extent is defined by the Köppen-Geiger classification of arid and semi-arid zones. The map was produced as part of Geoscience Australia's project: 'Water for Australia's arid zone—Identifying and assessing Australia's palaeovalley groundwater resources' which was funded by the National Water Commission. The four year project (2008–2012) was directed towards providing information about the role of palaeovalleys as aquifers in widespread regions where groundwater resources are scarce or need to be investigated for the future.
The WASANT Palaeovalley Map was compiled using national-scale datasets, including digital elevation models (DEM) and geological maps, along with existing geoscientific data and reports in combination with expert knowledge for local areas. An example of the map output, over the Hamersley Province in the Pilbara region of Western Australia, is shown in figure 1. The map includes palaeovalleys that are obscured beneath desert dunefields and sand plains, for example, the Dune Plains Palaeovalley in the NT (figure 2). New information was obtained through demonstration studies in selected sites within the three states. Examples of palaeovalley cross-sections from selected sites are shown on the map to illustrate the heterogeneity and distinctive characteristics of palaeovalleys that have evolved under different climatic and fluvial regimes in respective geologic provinces. Enlarged inset maps of areas where palaeovalleys are dense or particularly distinctive are displayed around the main national-scale map. Inset maps of arid zone climate regimes, geologic provinces, demonstration study sites, a processed DEM, and relevant references are also included.
The methodology adopted to generate the WASANT Palaeovalley Map is described in English et al (2012), along with interpretative descriptions and some noteworthy observations of palaeovalleys in specific regions. The map is sub-titled 'first edition' in anticipation that future updates, extensions and refinements might be made.