This interactive training module is an introduction to the theory, application and interpretation of gamma-ray spectrometry for regolith science. It uses descriptions, diagrams and three dimensional models to describe gamma-ray spectrometry for regolith science. The tutorial was created by Geoscience Australia and the Cooperative Research Centre for Landscape Environments and Mineral Exploration.

Seismic line 07GA-IG2, described here, forms part of the Isa-Georgetown-Charters Towers seismic survey that was acquired in 2007. The seismic line is oriented approximately east-west and extends from east of Croydon in the west to near Mt Surprise in the east (Figure 1). The acquisition costs for this line were provided jointly by the Geological Survey of Queensland and Geoscience Australia, and field logistics and processing were carried out by the Seismic Acquisition and Processing team from Geoscience Australia. Three discrete geological provinces have been interpreted on this seismic section (Figure 2). Two of these, the Numil and Abingdon Provinces, only occur in the subsurface. The upper crustal part of the seismic section consists of the Paleo- to Mesoproterozoic Etheridge Province, which here includes the Croydon Volcanic Group in the western part of the Province. In this east-west profile, the crust is essentially two-layered, with a strongly reflective lower crust defining the Numil and Abingdon Provinces and a less reflective upper crust being representative of the Etheridge Province.

The Capel and Faust basins are located on the northern Lord Howe Rise in water depths of 1300-2500 m. Geoscience Australia recently completed a geological and petroleum prospectivity assessment of the area based on new seismic, potential field, multibeam bathymetry and rock sample data. The data sets were acquired under Australian Geovernment initiatives aimed at providing pre-competitive information to industry.

The Capel and Faust basins are located over the northern part of the Lord Howe Rise, a large offshore frontier region containing a number of basins with untested petroleum prospectivity. Recent data acquisition by Geoscience Australia has significantly improved geological knowledge of these basins. Given the diversity of acquired data, comparative sparseness of data coverage, lack of deep drilling control, and complexity of geological structure, effective data integration and analysis methods were essential for a meaningful geological interpretation of the Capel and Faust basins. By using the 3D visualisation and modelling environment provided by GOCAD, the datasets were captured, processed and interpreted to create an integrated 3D model that enabled key geological and prospectivity questions to be answered. This presentation summarises the construction methodology and the resulting geological and prospectivity implications of the Capel-Faust 3D geological model.

The combined analysis of airborne electromagnetics (AEM), airborne gamma-ray spectrometry (AGRS), magnetics and a digital elevation model with ground-based calibration, has enable construction of a 3D architectural and landscape evolution model of valley fill deposits around the township of Jamestown in South Australia. The valley fill sediments consist of traction, suspension and debris-flow deposits that range in age (optically stimulated luminescence OSL dating) from 102 ka (±12) to the present day. A sediment isopach map generated from the AEM dataset reveals the 3D structure of the valley-fill deposits. The sediments are up to 40 m thick within asymmetrical valleys and are the result of colluvial fan, floodplain and sheet-wash processes. The sediments fine upwards with a higher proportion of coarser bed load deposits toward the base and fine sand, silt and clay towards the top of the sequence. A strong linear correlation between airborne K response and soil texture allowed the percentage of surface silt to be modelled over the depositional landforms. The sediments are thought to have been derived by a combination of aeolian dust accessions, and weathering and erosion of bedrock materials within the catchment. Older drainage lines reflected in the distribution of relatively closely spaced and well connected 'magnetic channels' differ markedly from present day streams that are largely ephemeral and interrupted. This is thought to reflect a change in local hydrology and associated geomorphic processes from relatively high to lower energy conditions as the valley alluviated. These hydrological changes are likely to be associated with a drying climate, lower recharge and runoff.

The Australian Government is developing enabling legislation that will underpin the development of safe and secure geological storage of greenhouse gases in Australia's offshore waters. The proposed legislation will facilitate the release of acreage for the identification and use of geological storage formations by industry proponents. A current proposal is that the release of the areas will be modelled on Australia's current system for the release of offshore petroleum acreage. This paper addresses the technical, policy, social, commercial, regulatory and economic issues to be considered in selecting areas to be released for geological storage in Australian offshore areas. Prospectivity for geological storage formations is the primary criterion for selection, and release areas will typically be defined on the basis of regional assessments. The paper briefly reviews the GEODISC program and its outcomes, and discusses the availability and limitations of other geological data used to support site selection. Regional examples of possible migration paths will be considered, and their impact on area boundaries, in conjunction with the licensing requirements of the proposed legislation. Source-sink matching is addressed, together with a discussion on the potential interactions with petroleum resources. Please Note: As at the submission date for abstracts, policy for geological storage in areas under the jurisdiction of the Australian Government is awaiting endorsement by the current Government. At this time, the abstract can therefore only consider issues relating to exploration acreage release in a universal manner, rather than specifically. If enabling legislation is passed, more specific examples of acreage selection may be provided, together with details of the legislative and regulatory constraints. The content of the paper is therefore dependent on the status of the legislation and release process at the time the paper is submitted.

SGA 2009 abstract

The frontier Capel and Faust Basins, 800 km east of Brisbane in water depths of 1000-3000 m, are generating interest in light of Australia's energy security concerns. The basins are a focus of Geoscience Australia's efforts to provide pre-competitive knowledge of offshore frontier regions to the petroleum exploration industry. A variety of new geophysical data has recently been obtained over these remote basins. A regional-scale residual gravity map, prepared from satellite-altimetry data and upward continuation, highlighted a series of N-S elongate gravity lows interpreted to represent basin depocentres. A 2D reflection seismic survey was designed on the basis of this gravity-inferred basin distribution. The survey was conducted in late 2006/early 2007 and provided 106-fold data to 12 s TWT on 5920 km of dip and strike lines. Sonobuoy data were recorded for velocity information. Additional ship-borne gravity and magnetic data were collected during the seismic survey and on a subsequent swath bathymetry and geological sampling survey in late 2007. The latter survey focussed on the north-western part of the seismic grid where depocentres appear to be best developed. The complex of small depocentres means that 2D potential field modelling is not appropriate, but the potential field data are being used as constraints to interpolate horizon and basement picks between the 20-50 km spaced seismic lines. Ultimately, these efforts will lead to a complete 3D picture of the upper crust that will assist assessments of the prospectivity of these remote but tantalising basins.

Geoscience Australia's World Wind Viewer is an application developed using NASA's World Wind Java Software Development Kit (SDK) to display Australia's continental data sets. The viewer allows you to compare national data sets such as the radioelements, the gravity and magnetic anomalies, and other mapping layers, and show the data draped over the Australian terrain in three dimensions.

A technical user manual for volcanic ash dispersion modelling using python-FALL3D.