From 1 - 10 / 500
  • 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.

  • Inland sulfidic soils have recently formed throughout wetlands of the Murray River floodplain associated with increased salinity and river regulation (Lamontagne et al., 2006). Sulfides have the potential to cause widespread environmental degradation both within sulfidic soils and down stream depending on the amount of carbonate available to neutralise acidity (Dent, 1986). Sulfate reduction is facilitated by organic carbon decomposition, however, little is known about the sources of sedimentary organic carbon and carbonate or the process of sulfide accumulation within inland sulfidic wetlands. This investigation uses stable isotopes from organic carbon (13C and 15N), inorganic sulfur (34S) and carbonate (13C and 18O) to elucidate the sources and cycling of sulfur and carbon within sulfidic soils of the Loveday Disposal Basin.

  • Extended abstract version of short abstract accepted for conference presentation GEOCAT# 73701

  • The Asia-Pacific region is highly susceptible to a variety of natural hazards. In particular, geophysical and atmospheric hazards threaten the livelihood of people within the region and the impacts of these hazards can significantly affect economic development. The Australian Agency for International Development (AusAID) has identified Disaster Risk Reduction as a priority in a number of countries in the Asia-Pacific region. Geoscience Australia is partnering with AusAID to strengthen the capacity of governments in Indonesia, the Philippines and Papua New Guinea to undertake natural hazard risk and impact analysis. The objective of these programs is to better prepare for, and protect from, natural disasters by informing the reduction in risk from various hazards. It is also expected that this enhanced capacity can be further applied to climate change impacts analysis. A key aspect of each the programs is the application of spatial information for hazard modelling, development of information on exposure (e.g. elements at risk such as residential buildings, key facilities, infrastructure) and the understanding of the vulnerability of structures, communities and infrastructure. Geoscience Australia is providing technical leadership and support to partner agencies in the identification of existing datasets and through provision of new and enhanced data. Geoscience Australia is supporting the development and management of value-added, spatially-enabled datasets in a number of locations to underpin the natural hazard risk analysis process. These activities also aim to provide technical partners with repeatable techniques and sustainable tools for the ongoing development and maintenance of these datasets into the future.

  • 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 response to emergency situations such as floods and fires demand products in short time frames. If you use remote sensing then the response typically involves detailed examination of imagery in order to determine the spectral bands, ratios and associated thresholds that map the desired features such as flood or burn extent. The trial and error process associated with manual threshold selection is often time consuming and can result in significant errors due to confounding factors such as clouds and shadowed areas. By modelling features such as flood waters or fire scars as Gaussian distributions, allowing for fuzzy thresholds with neighbouring features, the required thresholds can be automatically derived from the imagery and emergency events can have extents determined much more rapidly. Automatic threshold selection minimises trial and error, thereby dramatically reducing processing turn-around time.

  • Hot Rock geothermal exploration in Australia is significantly different to methods used for conventional geothermal plays elsewhere in the world. Hot Rock geothermal plays in the most essential form comprise a heat source and insulating layer. In Australia, high-heat producing granites (HHPG) are the presumed heat source, while low-conductivity sedimentary rocks provide the insulator necessary to create an accumulation of heat and elevated temperatures. It is presumed that other elements of a geothermal play can be introduced, such as using hydrofracturing or chemical treatment to achieve the required permeability, or the injection of circulation water.

  • This paper describes the methods used to define earthquake source zones and calculate their recurrence parameters (a, b, Mmax). These values, along with the ground motion relations, effectively define the final hazard map. Definition of source zones is a highly subjective process, relying on seismology and geology to provide some quantitative guidance. Similarly the determination of Mmax is often subjective. Whilst the calculation of a and b is quantitative, the assumptions inherent in the available methods need to be considered when choosing the most appropriate one. For the new map we have maximised quantitative input into the definition of zones and their parameters. The temporal and spatial Poisson statistical properties of Australia's seismicity, along with models of intra-plate seismicity based on results from neotectonic, geodetic and computer modelling studies of stable continental crust, suggest a multi-layer source zonation model is required to account for the seismicity. Accordingly we propose a three layer model consisting of three large background seismicity zones covering 100% of the continent, 25 regional scale source zones covering ~50% of the continent, and 44 hotspot zones covering 2% of the continent. A new algorithm was developed to calculate a and b. This algorithm was designed to minimise the problems with both the maximum likelihood method (which is sensitive to the effects of varying magnitude completeness at small magnitudes) and the least squares regression method (which is sensitive to the presence of outlier large magnitude earthquakes). This enabled fully automated calculation of a and b parameters for all sources zones. The assignment of Mmax for the zones was based on the results of a statistical analysis of neotectonic fault scarps.

  • The Australian Government formally releases new offshore exploration areas at the annual APPEA conference. In 2012, twenty-seven areas in nine 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. 8 November 2012 and 9 May 2013, depending on the exploration status in these areas and on data availability. As was the case in 2011, this year's Release again covers a total offshore area of about 200,000 km2. The Release Areas are located in Commonwealth waters offshore Northern Territory, Western Australia, South Australia, Victoria and Tasmania (Figure 1). Areas on the North West Shelf feature prominently again and include underexplored shallow water areas in the Arafura and Money Shoal basins and rank frontier deep water areas in the outer Browse and Roebuck basins as well as on the outer Exmouth Plateau. Following the recent uptake of exploration permits in the Bight Basin (Ceduna and Duntroon sub-basins) Australia's southern margin is well represented in the 2012 Acreage Release. Three new blocks in the Ceduna Sub-basin, four blocks in the Otway Basin, one large block in the Sorell Basin and two blocks in the eastern Gippsland Basin are on offer. Multiple industry nominations for this Acreage Release were received, confirming the healthy status of exploration activity in Australia. The Australian government continues to support these activities by providing free access to a wealth of geological and geophysical data.