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  • Update on Australia's oil and gas activities with a focus on recent exploration successes and promotion of open offshore acreage

  • Geoscience Australia (GA) has been developing the National Exposure Information System (NEXIS), a national database of exposure information to identify elements in both the built environment and community that are at risk from natural disasters. A key component of NEXIS is the description of each building including footprint area and height; these geometric characteristics can be derived from LiDAR. This investigation is an assessment of the current abilities of GA and industry partners to provide this data. GA holds LiDAR data representing 70% of the places Australians live, however most of these dataset have not been processed to identify buildings. Five software methods and five industry partners were assessed for their ability to do two main tasks: identify or classify buildings in the LiDAR point clouds, and extract geometric characteristics of buildings. The extracted features were assessed using an urban LiDAR point cloud that has good accuracy and a high data density. Feature-based and area-based assessment methods were developed to assess the output of software packages against a reference building dataset provided by the Launceston Council. The various methods achieved a producer's accuracy between 80% and 90%, user's accuracy between 70% and 90%, and overall accuracy between 90% and 95%.

  • Understanding the distribution of temperature is generally the first step in a geothermal exploration process. With the exception of a few areas of hot springs, there are no surface manifestations of temperature anomalism in Australia. The Australian continent has no active magmatism, the heat flow regime is conductive, and thick layers of insulating sediments are necessary to obtain elevated temperature suitable for electricity generation or process heat. The coverage of direct temperature measurements and surface heat flow determinations is described in Gerner and Holgate (2010). The majority of these measurements were made by petroleum and groundwater drilling, and is characterised by sparsity and poor distribution. An alternative approach is needed to provide indications of temperature at depth in uncharacterised areas, so that the whole of Australia can be evaluated for geothermal prospectivity.

  • Medhavy Thankappan1, Matthew Garthwaite1, Peter Meadows2, Nuno Miranda3, Adrian Schubert4 and David Small4 1Geoscience Australia, Canberra, Australia 2BAE Systems Applied Intelligence, Essex, United Kingdom 3European Space Agency, Frascati, Italy 4 Remote Sensing Laboratories, Department of Geography, University of Zurich, Switzerland Geoscience Australia has permanently deployed 40 trihedral corner reflectors in the Surat Basin, Queensland, Australia, covering an area of approximately 20,000 km2. The array of corner reflectors was constructed as part of the AuScope Australian Geophysical Observing System (AGOS) initiative to monitor crustal deformation using Interferometric Synthetic Aperture Radar (InSAR) techniques. The array includes 34 corner reflectors of 1.5m, 3 reflectors of 2.0m and 3 reflectors of 2.5m inner leg dimensions. Through the design process and the precision manufacturing techniques employed, the corner reflectors are also highly suitable for calibration and validation of Synthetic Aperture Radar (SAR) data acquired by satellites. Nine of the 1.5m corner reflectors in the AGOS array had their Radar Cross Section (RCS) individually characterised at the Defence Science and Technology Organisation's outdoor ground reflection range, prior to permanent deployment in the Surat Basin. The RCS measurements for the corner reflectors were carried out at X and C-band frequencies for both horizontal and vertical transmit-receive polarisations, and at a range of elevation and azimuth alignments. The results from the characterisation of the corner reflectors show that the measured RCS values were 2 decibels less than theoretical values at C-band and 5 decibels at X-band. The field performance of the AGOS corner reflectors has been studied using SAR data from the TerraSAR-X, RADARSAT-2, Sentinel-1A and ALOS-2 satellites. This paper presents the results of the corner reflector field performance at X, C and Lband SAR frequencies which the satellites cover. As part of the Copernicus Sentinel-1A satellite commissioning and routine phases, the European Space Agency's Mission Performance Centre has also undertaken exercises using data from the Sentinel-1A satellite to assess the field performance of the AGOS corner reflectors. Radiometric calibration results from that evaluation are presented here with recent geometric calibration and validation results for Sentinel-1A products from the Terrain Observation with Progressive Scans (TOPS) mode. The current configuration for most corner reflectors in the AGOS array is set to serve calibration requirements for a broad range of SAR missions on ascending orbital passes, and therefore may not be optimal for any single mission in particular. However, the design allows for mission-specific corner reflector alignment if needed, as in the case of the 2.5m and 2.0m reflectors which have specifically been aligned to support calibration of the L-band SAR instrument on ALOS-2. The permanently deployed AGOS corner reflector infrastructure presents an opportunity for independent calibration and comparison of SAR instruments on current and future satellite missions, and is considered an important Australian contribution to the global satellite calibration and validation effort.

  • Up to 90% of Australia's uranium resources occur in deposits of Paleo-Mesoproterozoic (~1.9-1.5 Ga) age, including hematite granitic breccias at Olympic Dam in South Australia and unconformity-related deposits in the Northern Territory. Published fluid inclusion data for unconformity-related uranium deposits suggest that uranium was transported by low- to moderate temperature (<250°C), Na-Ca-Mg brines of seawater evaporation origin. Secular changes in geochemical behaviour of uranium through Earth history are well known. The most prominent changes are attributed to stepped oxygenation of the Earth's atmosphere. This process resulted in oxidation of U(IV) to U(VI) forming highly soluble aqueous uranyl complexes. The oxygenation is thought to have occurred as two stepwise increases in atmospheric oxygen at the beginning and end of the Proterozoic, at ~2.3 and ~0.6 Ga. High aqueous mobility of uranium after the second oxygenation event is globally recorded by elevated concentrations of uranium in organic-rich shales. Large-scale processes of crustal enrichment of uranium in the Proterozoic rocks pre-dating the second oxygenation events can be explained by a number of endogenic factors, including high paleogeothermal gradients and large volumes of uranium-enriched granitic rocks emplaced at shallow crustal levels. Other decisive factors leading to the formation of the giant uranium deposits may be of exogenic origin. One would be a unique combination of moderately elevated levels of atmospheric oxygen and high levels of atmospheric CO2, with the latter exceeding present day levels at least by ~1.5 orders of magnitude. Under these conditions, for a wide range of surficial waters and groundwaters, uranium aqueous speciation would be dominated by carbonate uranyl complexes (e.g., UO2CO3), with uranyl concentrations proportional to CO2 pressures. Another exogenic factor is Paleoclimatic conditions favourable to the formation of evaporative basins suggested as sources of uraniferous fluids. In the present study, we examine these two exogenic factors quantitatively, modelling solubility of uranium in natural waters and progressively evaporated seawater at boundary conditions characteristic of Paleo-Mesoproterozoic atmosphere (log fCO2 > 2, log fO2 ~ 1.4). The modelling indicates that Paleo-Mesoproterozoic environment could be especially favourable for mobilisation of uranium in weathering profiles due to elevated content of atmospheric CO2. Evaporation of seawater is indeed a chemically feasible process that might have determined the initial (Na-Mg) composition of brines associated with uranium mineral systems. The range of the Na-Ca-Mg brine compositions reported in the literature can be explained by 'sampling of spatially separate parts of the same brine factory characterized by different degrees of seawater evaporation and the extent of the subsequent brine interaction with Ca-rich basin and basement lithologies via Na-Ca and Mg-Ca exchange reactions.

  • Abstract for 2015 Conference of the Specialist Group of Tectonics and Structural Geology. Presentation of 3D Models in the Grampians-Stavely Zone, western Victoria. 3D geological models have been produced for two major geological units in the Grampians-Stavely Structural Zone in western Victoria. The Grampians-Stavely Zone is located on the eastern limit of the Cambrian-aged Delamerian Orogen in Victoria (VandenBerg et al., 2000; Crawford et al., 2003; Miller et al., 2005) and several belts of Cambrian igneous rocks with arc affinities have been recognised within this zone (Crawford and Keays, 1978; Buckland, 1987; VandenBerg et al., 2000; Crawford et al., 2003); including the exposed Mount Stavely Volcanic Complex (Buckland, 1987). The Mount Stavely Volcanic Complex, together with other belts of Cambrian igneous rocks, have been interpreted as fault slices of a now mostly buried magmatic arc system referred to as the Stavely Arc (Schofield et al., 2015; Cayley et al., in prep.). In order to address the outstanding geological questions and challenges to exploration in the Grampians-Stavely Zone, Geoscience Australia and the Geological Survey of Victoria established the collaborative Stavely Project in 2013. The Stavely Project forms part of the broader UNCOVER initiative (Australian Academy of Science, 2012) and aims to provide the fundamental framework for discovery in the Grampians-Stavely Zone. This is done using a mineral systems-based approach (Wyborn et al., 1994) through the provision of pre-competitive geoscientific data. This approach involves characterising the subsurface geology, recognising favourable geological environments for the formation of major mineral systems, identifying important elements that demonstrate mineral systems potential, and understanding the depth and nature of cover across the region. This study will focus on understanding the depth and nature of specific cover units across the region.

  • To be submitted to the International Geological congress (IGC35)

  • Analysis of seismic velocity models and petrophysical modelling show that Archaean crust, particularly in the upper part, has remarkably similar overall composition, and the apparent differences in seismic models between the Ukrainian, Fennoscandian and Australian shields analysed in this paper can mostly be explained by different thermal regimes affecting equilibrium mineralogies at depth.

  • Indonesia is very prone to natural disasters, especially earthquakes, due to its location in a tectonically active region etc

  • IGC 2012 Title: Geochronological and geochemical evidence for a regional hydrothermal event during the 1590-1560 Ma Chewings Orogeny in the central Arunta Region, Northern Territory Authors: Eloise E Beyer1, Natalie Kositcin2 and Daniel J Dunkley2 1 Northern Territory Geological Survey, PO Box 8760, Alice Springs NT 0871 2 Geoscience Australia, GPO Box 378, Canberra ACT 2601