An extensive AEM survey recently commissioned by Geoscience Australia involved the use of two separate SkyTEM helicopter airborne electromagnetic (AEM) systems collecting data simultaneously. In order to ensure data consistency between the two systems, we follow the Danish example (conceived by the hydrogeophysics group from Aarhus University) of using a hover test site to calibrate the AEM data to a known reference. Since 2001, Denmark has employed a national test site for all electromagnetic (EM) instruments that are used there, including the SkyTEM system. The Lyngby test-site is recognised as a well-understood site with a well-described layered-earth structure of 5 layers. The accepted electrical structure model of the site acts as the reference model, and all instruments are brought to it in order to produce consistent results from all EM systems. Using a ground-based time-domain electromagnetic (TEM) system which has been calibrated at the Lyngby test site, we take EM measurements at a site selected here in Australia. With sufficient information of the instrument, we produce a layered-earth model that becomes the reference model for the two AEM systems used in the survey. We then bring the SkyTEM systems to the hover site and take soundings at multiple altitudes. From the hover test data and the ground based model, we calculate an optimal time shift and amplitude scale factor to ensure that both systems are able reproduce the accepted reference model. Conductivity sections produced with and without calibration factors show noticeably different profiles.

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.

The Australian Solid Earth and Environment Grid (SEEGrid) is an eResearch infrastructure established to link diverse and distributed datasets in the geosciences, enable seamless interoperability between these, and undertake remote data processing. We present an integration between the GPlates plate-tectonic geographic information system and SEEGrid. Such a linkage is for the first time providing the necessary computational aids for abstracting an enormous level of complexity required for frontier solid-Earth research, in particular 4D metallogenesis. We present a continental reconstruction case study involving a proterozoic link between the greater Northern and Southern Australian cratons by combining evidence from several data sets. Faults are extracted from SEEGrid via Web Feature Services, and are used in conjunction with gravity anomaly data to test competing spatial alignment models of the reconstructed cratons. Additional information obtained from palaeomagnetic poles, granite geochemistry, geochronology, age-dated igneous provinces and other geophysics datasets can be used to further constrain the reconstruction. The metallogenic consequences of the best-fit reconstruction are profound, since they raises the possibility that the mineral systems hosting the giant Olympic dam, Broken Hill and Mt Isa could be linked in a particular geometry, resulting in a revised metallogenic map. The flexibility and extensibility of this spatio-temporal data analysis platform lends itself to a wide range of use-cases, including linking high-performance geodynamic modelling to kinematic reconstructions, creating the framework for future 3D and 4D metallogenic maps.

The Australian Government formally releases new offshore exploration areas at the annual APPEA conference. In 2011, twenty-nine areas in eight offshore basins are being released for work program bidding. Closing dates for bid submissions are either six or twelve months after the release date, i.e. 13 October 2011 and 12 April 2012, depending on the exploration status in these areas and on data availability. The 2011 Release is the largest since the year 2000 with all 29 areas, located in Commonwealth waters offshore Northern Territory, Western Australia, Victoria and Tasmania, covering approximately 200,000 km2. The producing hydrocarbon provinces of the Carnarvon, Otway and Gippsland basins are represented by gazettal blocks that are located close to existing infrastructure and are supported by extensive open file data-sets. Other areas that are close to known oil and gas discoveries lie in the Caswell Sub-basin (eastern Browse Basin) and on the Ashmore Platform (north-western Bonaparte Basin). A particular aspect of the 2011 Release is provided by 13 areas in underexplored regions offshore Northern Territory and Western Australia all of which range from 100 to 280 graticular blocks in size. These areas, located in the Money Shoal; outer Browse, Roebuck, north-eastern Carnarvon, Southern Carnarvon and North Perth basins, offer new opportunities for data-acquisition and regional exploration. The release of three large areas in the Southern Carnarvon and North Perth basins is supported by new data acquired and interpreted by Geoscience Australia as part of the Offshore Energy Security Program, of which selected results are being presented at this year's conference.

The Beagle Sub-basin is a Mesozoic rift basin in the Northern Carnarvon Basin. Oil discovered at Nebo-1 highlights an active petroleum system. 3D seismic interpretation identified pre, syn and post-rift megasequences. Pre-rift fluvio-deltaic and marine sediments were deposited during a thermal sag phase of the Westralian Super Basin. Low rates of extension (Rhaetian to Oxfordian) deposited fluvio-deltaic and marine sediments. During early post-rift thermal subsidence, sediments onlapped and eroded tilted fault blocks formed during the syn-rift phase. Consequently the regional seal (Early Cretaceous Muderong Shale) is absent in the centre. Subsequent successions are dominated by a prograding carbonate wedge showing evidence of erosion from tectonic and eustatic sea level change. 1D burial history modeling of Nebo-1 and Manaslu-1 show that all source rocks are currently at their maximum depths of burial. Sediments to the Late Cretaceous are in the early maturity window for both wells. The Middle Jurassic Legendre Formation reaches mid maturity in Nebo-1. Source, reservoir and seals are present throughout the Triassic to earliest Cretaceous, however, the absence of the regional seal in the central sub-basin reduces exploration targets. The lack of significant inversion increases the likelihood of maintaining trap integrity. Potential plays include compaction folds over tilted horst blocks, roll over and possible inversion anticlines, basin floor fans and intra-formational traps within fluvio-deltaic deposits. Late Cretaceous and younger sediments are unlikely to host significant hydrocarbons due to lack of migration pathways. Source rocks are of adequate maturity and deep faults act as pathways for hydrocarbon migration.

We report four lessons from experience gained in applying the multiple-mode spatially-averaged coherency method (MMSPAC) at 25 sites in Newcastle (NSW) for the purpose of establishing shear-wave velocity profiles as part of an earthquake hazard study. The MMSPAC technique is logistically viable for use in urban and suburban areas, both on grass sports fields and parks, and on footpaths and roads. A set of seven earthquake-type recording systems and team of three personnel is sufficient to survey three sites per day. The uncertainties of local noise sources from adjacent road traffic or from service pipes contribute to loss of low-frequency SPAC data in a way which is difficult to predict in survey design. Coherencies between individual pairs of sensors should be studied as a quality-control measure with a view to excluding noise-affected sensors prior to interpretation; useful data can still be obtained at a site where one sensor is excluded. The combined use of both SPAC data and HVSR data in inversion and interpretation is a requirement in order to make effective use of low frequency data (typically 0.5 to 2 Hz at these sites) and thus resolve shear-wave velocities in basement rock below 20 to 50 m of soft transported sediments.

The development of climate change adaptation policies must be underpinned by a sound understanding of climate change risk. As part of the Hyogo Framework for Action, governments have agreed to incorporate climate change adaptation into the risk reduction process. This paper explores the nature of climate change risk assessment in the context of human assets and the built environment. More specifically, the paper's focus is on the role of spatial data which is fundamental to the analysis. The fundamental link in all of these examples is the National Exposure Information System (NEXIS) which has been developed as a national database of Australia's built infrastructure and associated demographic information. The first illustrations of the use of NEXIS are through post-disaster impact assessments of a recent flood and bushfire. While these specific events can not be said to be the result of climate change, flood and bushfire risks will certainly increase if rainfall or drought become more prevalent, as most climate change models indicate. The second example is from Australia's National Coastal Vulnerability Assessment which is addressing the impact of sea-level rise and increased storms on coastal communities on a national scale. This study required access to or the development of several other spatial databases covering coastal landforms, digital elevation models and tidal/storm surge. Together, these examples serve to illustrate the importance of spatial data to the assessment of climate change risk and, ultimately, to making informed, cost-effective decisions to adapt to climate change.

The National Geochemical Survey of Australia aims to provide pre-competitive data and knowledge to support exploration for energy resources in Australia by documenting the chemical composition of Australia's regolith. It is a collaborative project between Geoscience Australia and all State and Northern Territory geological surveys, which commenced in 2007 and is due to conclude in mid-2011. A number of products, including a geochemical atlas of Australia, will be published. Over a two-year period, nearly 6000 samples from 1315 sites covering ~80% of Australia were analysed in the Geoscience Australia laboratories by XRF, ICP-MS and other associated techniques for major and trace elements. An analytical methodology was developed and tested through work on several pilot projects and trials during the development phase of the project. Samples were analysed by XRF using lithium metaborate fused beads at a dilution rate of 1:8. After XRF analysis of major elements and selected trace elements, a 200 mg sub-sample of this bead was acid-digested and analysed by reaction cell ICP-MS for trace elements. Quality was monitored by Certified Reference Materials, secondary standards, blind sampling duplicates, laboratory duplicates and analysis of some elements (Rb, Sr, Cu, Ni, Zr) by both instruments. This presentation will give an outline of the sampling and analytical methods used by the Geoscience Australia laboratories to ensure that results produced by the laboratory were accurate, consistent and traceable for the duration of the project.

This year, the Commonwealth Government is offering 6 large exploration areas in the frontier Bight Basin. The release areas (Figure 1) are situated in the central Great Australian Bight off southern Australia, approximately 415 to 655 km west of Port Lincoln, South Australia and 250 to 530 km southwest of Ceduna, South Australia. The areas are located within the Ceduna Sub-basin, in the eastern part of the Bight Basin, in water depths ranging from 130 to 4600 m. At present, no permits are held in this part of the basin. The release areas range in size from 85 to 90 graticular blocks (6000 to 6395 km2), and bids for all 6 areas close on 29 April 2010. Most exploration drilling in the Bight Basin has focused on the margins of the Ceduna Sub-basin and the Duntroon Sub-basin to the southeast of the current release areas. Gnarlyknots 1A, drilled by Woodside Energy and partners in 2003, is the only well to have attempted to test the thick, prospective Ceduna Sub-basin succession away from the margins of the sub-basin. Unfortunately the well was not an exploration success, as it had to be abandoned due to deteriorating weather and ocean conditions without reaching all planned target horizons. In 2007, Geoscience Australia conducted a marine sampling survey in the Bight Basin that dredged a suite of organic-rich rocks of Cenomanian-Turonian age from the northwestern exposed edge of the Ceduna Sub-basin. Geochemical analyses have characterised these samples as world-class, oil-prone, marine potential source rocks. Seismic interpretation indicates that this interval can be mapped throughout most of the basin and is mature for oil and gas generation across much of the Ceduna Sub-basin.

In the present study, the relative distributions and stable carbon and hydrogen isotopic compositions of the biomarkers from high grade oil shales (Permian and Carboniferous torbanites) rich in B. braunii fossils (i.e. torbanites) deposited under a range of climatic conditions are stringently scrutinised for any evidence of molecular features which may be characteristic of palaeogeographical location of deposition. Eleven torbanites from Scotland, South Africa and Australia covering the Late Carboniferous to Late Permian have been analysed.