We present a new method for the inversion of airborne gamma-ray spectrometric line data to a regular grid of radioelement concentration estimates on the ground. The method incorporates the height of the aircraft, the 3D terrain within the field of view of the spectrometer, the directional sensitivity of rectangular detectors, and a source model comprising vertical rectangular prisms with the same horizontal dimensions as the required grid cell size. The top of each prism is a plane surface derived from a best-fit plane to the digital elevation model of the earth's surface within each grid cell area. The method is a significant improvement on current methods, and gives superior interpolation between flight lines. It also eliminates terrain effects that would normally remain in the data with the use of conventional gridding methods.

AAMHatch acquired Airborne Laser Scanning (ALS) data for the Sydney Metropolitan area between 11 June 2007 & 7 July 2007 and again in February to June 2008. The source data are available as mass points (ASCII XYZ, LAS) and Gridded 2m and 10m DEM tiles or 2m Mosaic. The vertical accuracy is 0.15m at 1 sigma in open clear ground as specified in the project scope. A hydrologically conditioned and drainage enforced 2m DEM or HDEM has also been developed by SKM in both MGA Zone 56 and in GCA GDA94 projection in ESRI GRID format. Hydrologic enforcement and conditioning has included the testing of data for sinks, the referencing of transport and hydrology vector layers for intersections and flow, and the use of high-resolution imagery for visual validation. The methodology for hydrologic enforcement has required deriving a stream network based on flow direction and accumulation, using TIN and ANUDEM processes to analyse sinks and artificial damming affects caused by objects such as roads, bridges and trees which have not been previously filtered. Break lines have been included via the insertion of culvert/drainage channels, which has been used to interpolate these features into the main DEM as descending grid values. All data are referenced to GDA94/MGA Zone 56 and AHD using independent survey control which means the project area is not seamless and height difference between the 2007 and

Geoscience Australia (GA) has developed an interactive 3D virtual globe viewer to facilitate effective communication of geoscience data and scientific findings to a wide range of stakeholders. The interactive virtual globe is built on NASA's open source World Wind Java Software Development Kit (SDK) and provides users with easy and rich access to geoscientific data. The tool has been used to launch a number of national and regional datasets, including sub-surface seismic and airborne electromagnetic data (AEM) in conjunction with other relevant geoscience data. For the Broken Hill Managed Aquifer (BHMAR Project, there was a requirement to further develop the existing viewer platform in order to display complex 3D hydrogeological, hydrogeophysical and hydrogeochemical data (points, lines, 2D surface and 3D shapes). The final product includes support for a variety of geo-referenced raster data formats, as well as vector data such as ESRI shapefiles; native support for a variety of GOCAD data types including TSurf, SGrid, Voxet and PLine. It also supports well and borehole data including attribute-based styling of log features and the ability to include legends and descriptions of data within the user interface. An easy-to-use interface has been customised for navigation of data in 3D space using a virtual globe model, with powerful keyframe based animation tools used to generate flythrough animations for use in knowledge communication workshops. The products will be distributed as data layers via the internet and as a stand alone DVD package.

Abstract # : 1479734 Paper # : GP43B-1142 Session : GP43B Potential-field and EM methods for geologic problems of the mid and upper crust Developments for 3D gravity and magnetic modeling in spherical coordinates Richard Lane - Geoscience Australia - rjllane@gmail.com Qing Liang - China University of Geosciences (Wuhan) - qingliang.cug@gmail.com Chao Chen - China University of Geosciences (Wuhan) - chenchao@cug.edu.cn Yaoguo Li - Colorado School of Mines - ygli@mines.edu At Geoscience Australia (GA), Australia's Commonwealth Government geoscientific agency, we perform gravity and magnetic modeling at a range of scales, from broad regional crustal studies with thousands of kilometer lateral extent and tens of kilometer vertical extent, to detailed local studies with kilometer or less lateral extent and meters to hundreds of meters vertical extent. To achieve greater integration and coherence, and to better understand the geological significance of this work, we are investing in a number of development projects; * Spherical coordinate gravity and magnetic modeling, * Modeling using High Performance Computing facilities, * Utilizing rock property data as an input into the modeling and interpretation of gravity and magnetic data, * Better management of geoscience data and models, and * Visualization of spatial data in a Virtual Globe format. In collaboration with the Colorado School of Mines (CSM) and the China University of Geosciences (CUG), we are developing a capability to model gravity and magnetic data in a spherical coordinate framework. This will provide more accurate calculations and permit us to integrate the results into a single framework that more realistically reflects the shape of the Earth. Modeling gravity and magnetic data in a spherical coordinate framework is far more compute intensive than is the case when performing the corresponding calculations in a Cartesian (rectangular) coordinate framework. To reduce the time required to perform the calculations in a spherical coordinate framework, we will be deploying the modeling software on the National Computational Infrastructure (NCI) High Performance Computing (HPC) facility at the Australian National University (ANU). This will also streamline the management of these software relative to the other main option of establishing and maintaining HPC facilities in-house. We are a participant in the Deep Exploration Technologies Cooperative Research Centre (DET CRC). In combination with this involvement, we are expanding our support for systematic management of rock property data, and developing a better understanding of how these data can be used to provide constraints for the modeling work. We are also using the opportunities afforded through the DET CRC to make progress with documentation and standardization of data storage and transfer formats so that the tasks of management, discovery and delivery of this information to users are simplified and made more efficient. To provide the foundations of integration and analysis of information in a spatial context, we are utilizing and customizing 3D visualization software using a Virtual Globe application, NASA World Wind. This will permit us to view the full range of information types at global to local scales in a realistic coordinate framework. Together, these various development activities will play an important role in the on-going effort by Geoscience Australia to add value to the potential field, rock property, and geological information that we possess. We will then be better able to understand the geology of the Australian region and use this knowledge in a range of applications, including mineral and energy exploration, natural hazard mitigation, and groundwater management.

3D visualisation of the Mount Isa Crustal Seismic Survey

The Georgina-Arunta 3D project is a body of work that is predominantly focussed around delivery of 3D geophysical and geological data and interpretations to support the seismic data in the region. By integrating all available data in the region with a wide variety of potential-field techniques, a robust 3D map is able to be produced.

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.

Geoscience Australia has developed an interactive 3D viewer for three national datasets; the new Radiometric Map of Australia, the Magnetic Anomaly Map of Australia, and the Gravity Anomaly Map of the Australian Region. The interactive virtual globe is based on NASA's open source World Wind Java Software Development Kit (SDK) and provides users with easy and rich access to these three national datasets. Users can view eight different representations of the radiometric map and compare these with the magnetic and gravity anomaly maps and satellite imagery; all draped over a digital elevation model. The full dataset for the three map sets is approximately 55GB (in ER Mapper format), while the compressed full resolution images used in the virtual globe total only 1.6GB and only the data for the geographic region being viewed is downloaded to users computers. This paper addresses the processes for selecting the World Wind application over other solutions, how the data was prepared for online delivery, the development of the 3D Viewer using the Java SDK, issues involving connecting to online data sources, and discusses further development being undertaken by Geoscience Australia.

Australian Phanerozoic basins have been under-explored for uranium. As a result, Geoscience Australia has been conducting research into uranium systems in the Frome Embayment, with the aim of developing a series of models and exploration techniques to assist uranium exploration in other basins. The transport and depositional mechanisms are relatively well understood for sandstone-hosted uranium deposits; uranium is transported by oxidised meteoric fluids and precipitated by either an in situ reductant or by mixing with a reduced fluid. Using the concept that an oxidised fluid will progressively oxidise the rock that it passes through and, in turn the fluid will be reduced by wall rock interactions, potentially we can use drillhole logs to identify and map the redox state of the rocks and hence identify depositional sites. A pilot study was undertaken to determine whether the open file geological logs could be used to map the redox state. A list of oxidised and reduced keywords was identified from the logs. Logs were digitised and oxidised words were given a value of one and reduced words given a value of negative one. Where there was combination of oxidised and reduced words, zero was used to designate the intermediate redox state. Where redox state could not be determined from the logs, a null data value was used. The redox values were imported into gOcad and gridded using DSI and IDW for comparison purposes. The technique identified north-south trending features in the Namba Formation interpreted to be previously unmapped paleochannels. This technique of mapping redox conditions of sediments using open file drilling reports is able to be applied in other basin settings, assisting in the targeting of sandstone-hosted uranium systems.

The Eromanga Basin has the potential to contain significant sandstone-hosted uranium mineralisation. Publicly available geophysical and geochemical datasets have been integrated into a 3D geological map for the Eromanga Basin. Initial uranium mineral system assessment has highlighted two regions of potential exploration significance: the region east of Mt Isa corresponding to the Euroka Arch and the area southwest of Lake Eyre.