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This preliminary report will provide a geochemical and ionic characterisation of groundwater, to determine baseline conditions and, if possible, to distinguish between different aquifers in the Laura basin. The groundwater quality data will be compared against the water quality guidelines for aquatic ecosystem protection, drinking water use, primary industries, use by industry, recreation and aesthetics, and cultural and spiritual values to assess the environmental values of groundwater and the treatment that may be required prior to reuse or discharge.
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Vertical geochemical profiling of the marine Toolebuc Formation, Eromanga Basin - implications for shale gas/oil potential The regionally extensive, marine, mid-Cretaceous (Albian) Toolebuc Formation, Eromanga Basin hosts one of Australia's most prolific potential source rocks. However, its general low thermal maturity precludes pervasive petroleum generation, although regions of high heat flow and/or deeper burial may make it attractive for unconventional (shale gas and shale oil) hydrocarbon exploration. Previous studies have provided a good understanding of the geographic distribution of the marine organic matter in the Toolebuc Formation where total organic carbon (TOC) contents range to over 20% with approx. half being of labile carbon and convertible to gas and oil. This study focuses on the vertical profiling, at the decimetre to metre scale, of the organic and inorganic geochemical fingerprints within the Toolebuc Formation with a view to quantify fluctuations in the depositional environment and mode of preservation of the organic matter and how these factors influence hydrocarbon generation thresholds. The Toolebuc Formation from three wells, Julia Creek-2 and Wallimbulla-2 and -3, was sampled over an interval from 172 to 360m depth. The total core length was 27m from which 60 samples were selected. Cores from the underlying Wallumbilla Formation (11 samples over 13m) and the overlying Allaru Mudstone (3 samples) completed the sample set. Bulk geochemical analyses included %TOC, %carbonate, %total S, -15N kerogen, -13C kerogen, -13C carbonate, -18O carbonate, and major, minor and tracer elements and quantitative mineralogy. More detailed organic geochemical analyses involved molecular fossils (saturated and aromatic hydrocarbons, and metalloporphyrins), compound specific carbon isotopes of n-alkanes, pyrolysis-gas chromatography and compositional kinetics. etc.
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The impacts of climate change on sea level rise (SLR) will adversely affect infrastructure in a significant number of Australian coastal communities. A first-pass national assessment has identified the extent and value of infrastructure potentially exposed to impacts from future climate by utilizing a number of fundamental national scale datasets. A mid-resolution digital elevation model was used to model a series of SLR projections incorporating 100 year return-period storm-tide estimates where available (maximum tidal range otherwise). The modeled inundation zones were overlaid with a national coastal geomorphology dataset, titled the Smartline, which identified coastal landforms that are potentially unstable under the influence of rising sea level. These datasets were then overlain with Geoscience Australia's National Exposure Information System (NEXIS) to quantify the number and value of infrastructure elements (including residential and commercial buildings, roads and rail) potentially vulnerable to a range of sea-level rise and coastal recession estimates for the year 2100. In addition, we examined the changes in exposure under a range of future Australian Bureau of Statistics population scenarios. We found that over 270,000 residential buildings are potentially vulnerable to the combined impacts of inundation and recession by 2100 (replacement value of approximately $A72 billion). Nearly 250,000 residential buildings were found to be potentially vulnerable to inundation only ($A64 billion). Queensland and New South Wales have the largest vulnerability considering both value of infrastructure and the number of buildings affected. Nationally, approximately 33,000 km of road and 1,500 km of rail infrastructure are potentially at risk by 2100.
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Mineral deposits, although geographically small in extent, are the result of processes-which together form a mineral system-that occur, and can be mapped at, a variety of scales, up to craton-scale and larger. The mineral system approach has the benefit that in it focuses on critical processes and can include larger scales not always considered. Understanding the four-dimensional evolution of the crust, for example, is important, as it can provide critical constraints on the geodynamic history, the lithospheric architecture and development, and potentially identify metallogenic terranes. Constraining the nature and evolution of the crust is not easy, however, given its largely inaccessible nature. Just as the study of basaltic rocks has provided insight into the earth's mantle, granites, provide a window into the middle and lower continental crust. Studies of these rocks are enhanced by the use of isotopic tracers (e.g., U-Pb, Sm-Nd, Lu-Hf), long used to provide constraints on geological processes and components involved in those processes.
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Fugitive methane emissions, in particular relating to coal seam gas (CSG),has become an emerging issue in Australia over the last few years. There has been significant controversy in US regarding the magnitude of fugitive emissions during production from unconventional gas wells, with large differences in emissions reported between studies using different measurement approaches. . Preliminary research into a small number of Australia's unconventional fields suggest the average fugitive emissions per well are lower than that found in the US. The primary challenge is that the techniques for quantifying methane leakages are still at an early stage of development. Current methods for the small to medium scale use chamber based approaches or vehicles installed with fixed sampling lines and high precisions gas analysers. These technologies are promising, but generally have not been ground truthed in field conditions against known emission rates to estimate effectiveness. They also have limited application in environments where vehicle access is not possible. The Ginniderra facility is being upgraded to support a methane controlled release experiment in 2015. This will enable testing of and verifying methods and technologies for measuring and quantifying methane emissions. To address the absence of suitable techniques for emmission measurement at medium scales, several BOREAL lasers will be deployed which work at scales of 20-1000 m. It is also envisaged airborne techniques utilising laser and hyperspectral will be deployed, along with tomography work utilising multiple concurrent concentration measurements.
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Spatially continuous data of environmental variables is often required for marine conservation and management. However, information for environmental variables is usually collected by point sampling, particularly for the deep ocean. Thus, methods generating such spatially continuous data by using point samples to estimate values for unknown locations become essential tools. Such methods are, however, often data- or even variable- specific and it is difficult to select an appropriate method for any given dataset. In this study, 14 methods (37 sub-methods) are compared using samples of mud content with five levels of sample density across the southwest Australian margin. Bathymetry, distance to coast, and slope were used as secondary variables. Ten-fold cross validation with relative mean absolute error (RMAE) and visual examination were used to assess the performance of these methods. A total of 1,850 prediction datasets were produced and used to assess the performance of the methods. Considering both the accuracy and the visual examination, we found that a combined method, random forest and ordinary kriging (RKrf), is the most robust method. No threshold in sample density was detected in relation to prediction accuracy. No consistent patterns were observed between the performance of the methods and data variation. The RMAE of three most accurate methods is about 30% lower than that of the best methods in previous publications, highlighting the robustness of the methods selected in this study. The limitations of this study were discussed and a number of suggestions were provided for further studies.
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The shallow water equations are widely used to model flood and tsunami flows, for example to develop inundation maps for hazard and risk assessments. Finite volume numerical methods are commonly used to derive approximate solutions to these problems, because of their potential to exactly conserve mass and momentum, and correctly simulate both smoothly and rapidly varying flows. However, there remain several common scenarios which often cause numerical difficulties. The occurrence of stationary water near complex wet-dry boundaries is a standard initial condition for tsunami applications. Many numerical methods will generate spurious waves in this situation, which can propagate into the flow domain and contaminate the solution. A related situation involves the simulation of run-off caused by direct rainfall inputs, which is often desirable for flood applications as an alternative to providing discharge inputs derived from rainfall-runoff models. Conserving mass and avoiding unrealistic 'spikes' in the simulated flow velocities can be challenging, particularly when the flow depth is much shallower than the elevation range of each mesh cell, as is practically unavoidable in large scale applications. Several techniques to robustly treat these situations have been implemented in variants of the ANUGA hydrodynamic model, and the performance of these is assessed in a range of ideal and practical examples.
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Open Geospatial Consortium (OGC) web services offer a cost efficient technology that permits transfer of standardised data from distributed sources, removing the need for data to be regularly uploaded to a centralised database. When combined with community defined exchange standards, the OGC services offer a chance to access the latest data from the originating agency and return the data in a consistent format. Interchange and mark-up languages such as the Geography Markup Language (GML) provide standard structures for transferring geospatial information over the web. The IUGS Commission for the Management and Application of Geoscience Information (CGI) has an on-going collaborative project to develop a data model and exchange language based on GML for geological map and borehole data, the GeoScience Mark-up Language (GeoSciML). The Australian Government Geoscience Information Committee (GGIC) has used the GeoSciML model as a basis to cover mineral resources (EarthResourceML), and the Canadian Groundwater Information Network (GIN) has extended GeoSciML into the groundwater domain (GWML). The focus of these activities is to develop geoscience community schema that use globally accepted geospatial web service data exchange standards.
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After CO2 is injected into the saline aquifer, the formation water inside the porous media becomes more acidic. This will significantly affect the original chemical equilibrium underground, and induce or speed up various processes of dissolution and precipitation depending on the reservoir pressure, temperature and salinity of formation water. The Early Cretaceous Gage Sandstone has been identified as a potential reservoir unit suitable for large-scale CO2 storage in the offshore southern Perth Basin. This study assesses the contribution of mineralisation trapping to CO2 storage capacity of the Gage Sandstone through a comprehensive geochemical modelling.
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The Australian Government formally releases new offshore exploration areas at the annual APPEA conference. These areas are located across various offshore hydrocarbon provinces ranging from mature basins with ongoing oil and gas production to exploration frontiers. In support of the annual acreage release, Geoscience Australia (GA) provides a variety of technical information with an emphasis on basin evolution, stratigraphic frameworks and overviews of hydrocarbon prospectivity. In recent years, GA's petroleum geological studies have significantly high graded the prospectivity of large underexplored offshore regions such as the Ceduna Sub-basin and the Northern Perth Basin. A new program is now targeting areas that lie adjacent to producing regions with the aim to delineate the occurrence and distribution of petroleum systems elements in less explored or in unsuccessful areas and to provide a comprehensive overview of the regional geological evolution. Updates to the stratigraphic framework and new results from geochemical studies are already available and are used for prospectivity assessments. Furthermore, the Australian government continues to assist offshore exploration activities by providing free access to a wealth of geological and geophysical data.