AusGeo News December 2007 Issue No. 88
Airborne geophysical survey marks major milestone
The Australia-wide airborne geophysical tie-line survey (AWAGS 2) was one of the world's largest airborne geophysical surveys.
The project, flown under contract by UTS Geophysics, was part of the five-year Onshore Energy Security Program (OESP), which commenced 18 months ago.
Data acquisition for AWAGS 2 began from Albany, Western Australia in March and flying was completed in December 2007. The survey, across the entire Australian mainland and Tasmania, included the acquisition of more than 145 000 kilometres of radiometric and magnetic data on northsouth flight lines spaced 75 kilometres apart, with a nominal flying height of 80 metres above ground level (figure 1).
The survey acquired radiometric data from a single aircraft, calibrated to international standards. The specially prepared aircraft flew at about 260 kilometres per hour, acquiring radiometric readings every 70 metres and magnetic readings every 7 metres (figure 2). The aircraft flew for eight or nine hours each day using a crew of two pilots. The survey was planned and executed such that flights were continuous on most days.
With completion of the survey the contractor will process the acquired data and expects to supply the final processed data to Geoscience Australia by March 2008. The processed radiometric data from AWAGS 2 will form the Australian radioelement datum and be used to adjust data in the national radiometric database (all Commonwealth and state public-domain data) to the standard. The survey will also be the datum for airborne radiometric data acquired in the future.
The processed magnetic data will increase the resolution of the Australian magnetic anomaly map and will be incorporated into continental-scale datasets. These will fill the gap between wavelengths of about 100 kilometres from airborne surveys and those exceeding 400 kilometres from satellites.
Other OESP work involved the acquisition of gravity, airborne electromagnetic (AEM) and seismic data in Queensland.
Geoscience Australia released new gravity data, acquired over parts of the Cooper Basin in the state's southwest, through the Geophysical Archive Data Delivery System in October 2007. The data are an important component of the OESP and will help in the assessment of hydrocarbon potential in the region, and in the identification of granites with possible geothermal energy potential in areas beneath the basin.
The first AEM survey to be conducted under the OESP started in the Paterson Province of Western Australia in September 2007. The survey is scheduled to be completed in mid-2008, with results to be released later that year. As outlined in AusGeo News 86, the results of the work are keenly awaited: they will give hints on the region's uranium potential.
The next AEM survey, planned for the Pine Creek Province in the Northern Territory, is expected to start in the second half of 2008. The province is prospective for several styles of uranium deposits. AEM data should make it possible to construct a 3D model of the basin architecture, map graphitic conductors in the basement, regolith thickness, and locate major structures and possible mineralising fluid pathways. Other AEM surveys are being scoped to target uranium and thorium systems elsewhere across the continent. In some areas, AEM data may also help in land and water management.
In September 2007, Geoscience Australia completed a major program of deep seismic data acquisition transecting northeast from the Mt Isa – Cloncurry region in Queensland towards Georgetown and then southeast to about 100 kilometres south of Charters Towers (figure 3). In total, 1175 kilometres of reflection data were acquired. The results of the survey will be released progressively from early 2008, The survey will help in the assessment of uranium, geothermal energy and hydrocarbon resource potential in the state's northwest.
The next seismic survey under the OESP is scheduled to start in mid-2008 in the Rankin Springs and Yathong troughs of the Darling Basin in western New South Wales. There is virtually no seismic coverage in the troughs, but they have been identified as one of the regions with the highest petroleum prospectivity in the basin. Geoscience Australia wants to assess the petroleum potential of the area by identifying potential source rocks in the troughs, along with structures and stratigraphy significant for hydrocarbon migration and entrapment. Seismic data acquisition projects will follow in South Australia in 2009 and northern Western Australia in 2010.
Meanwhile, planning and early work under the national projects (uranium, petroleum and geothermal energy) began in mid-2007:
National geoscience agreements under the National Geochemistry Survey of Australia project are now in place with all states and the Northern Territory. The training of field teams is complete in most places, and more than 130 catchments (about 10% of the total) have been sampled.
Updates on the OESP will continue in AusGeo News, in Geoscience Australia's monthly Minerals Alert, and on the program's website.
For more information phone Bill McKay on +61 2 6249 9003 (email email@example.com)
Onshore Energy Security Program underway (AusGeo News 84)
Onshore Energy Security Program takes off (AusGeo News 86)
Energy Security Initiative updates (AusGeo News 87)
In search of the next hotspot (AusGeo News 87)