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  • This dataset maps the geomorphic habitat environments (facies) for 88 Tasmanian coastal waterways. The classification system contains 11 easily identifiable and representative environments: Barrier/back-barrier, Bedrock, Central Basin, Channel, Coral, Flood- and Ebb-tide Delta, Fluvial (bay-head) Delta, Intertidal Flats, Rocky Reef, Saltmarsh/Saltflat, Tidal Sand Banks (and Unassigned). These types represent habitats found across all coastal systems in Australia. The majority of near pristine estuaries in Tasmania are located in the south and west of the State and on Cape Barren Island, according to the Department of Primary Industries, Water and Environment.

  • A new digital surface geology dataset covering Australia at 1:1 million scale was released recently by Geoscience Australia. The digital map, which depicts geological units and structures seamlessly across state and territory borders, will provide an invaluable baseline dataset for national and regional evaluation of resources as well as environmental management and land use decision-making. This national project was undertaken with the full co-operation of the geological surveys of each Australian state and the Northern Territory who provided their most recent map data for the national compilation as well as their advice in resolving stratigraphic issues.

  • Validation of spectral remote sensing data for geological mapping and detection of hydrothermal footprints in the Mount Isa Inlier

  • Identifying and mapping regolith materials at the regional and continental-scale can be facilitated via a new generation of remote sensing methods and standardised geoscience products. The multispectral Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) is the first Earth observation (EO) system to acquire complete coverage of the Australian continent. The Japanese ASTER instrument is housed onboard the USA's Terra satellite, and has 14 spectral bands spanning the visible and near-infrared (VNIR - 500-1,000 nm - 3 bands @ 15 m pixel resolution); shortwave-infrared (SWIR - 1,000-2,500 nm range - 6 bands @ 30 m pixel resolution); and thermal infrared (TIR 8,000-12,000 nm - 90 m pixel resolution) with a 60 km swath. Although ASTER spectral bands do not have sufficient spectral resolution to accurately map the often small diagnostic absorption features of specific mineral species, which can be measured using more expensive 'hyperspectral' systems, current coverage of hyperspectral data is very restricted. The extensive coverage and 30m pixel size of ASTER make it well suited to national scale work. The spectral resolution of ASTER make it best suited to mapping broader 'mineral groups', such as the di-octahedral 'Al-OH' group comprising the mineral sub-groups (and their minerals species) like kaolins (e.g. kaolinite, dickite, halloysite), white micas (e.g. illite, muscovite, paragonite) and smectites (e.g. montmorillonite and beidellite). Extracting mineral group information using ASTER, using specially targeted band combinations, can find previously unmapped outcrop of bedrocks, weathering products, help define soil type and chemistry, and delineate and characterise regolith and landform boundaries over large and remote areas.

  • The eastern Yilgarn Craton (EYC) of Western Australia is Australia's premier gold and nickel province, and has been the focus of geological investigations for over a century. Geoscience Australia, in conjunction with partners in the Predictive Mineral Discovery Cooperative Research Centre conducted a series of projects between 2001 and 2008 (Y4 project team, 2008). This article summarises the highlights and new findings from the research, many of which challenge previous paradigms on the tectonics and architecture, as well as the relationship of gold to structure, magmatism and metamorphism. Although a Yilgarn-based study, the results have general implications for other Archaean terranes.

  • This study used angular response curves of multibeam backscatter data to predict the distributions of seven seabed cover types in an acoustically-complex area. Several feature analysis approaches on the angular response curves were examined. A Probability Neural Network model was chosen for the predictive mapping. The prediction results have demonstrated the value of angular response curves for seabed mapping with a Kappa coefficient of 0.59. Importantly, this study demonstrated the potential of various feature analysis approaches to improve the seabed mapping. For example, the approach to derive meaningful statistical parameters from the curves achieved significant feature reduction and some performance gain (e.g., Kappa = 0.62). The first derivative analysis approach achieved the best overall statistical performance (e.g., Kappa = 0.84); while the approach to remove the global slope produced the best overall prediction map (Kappa = 0.74). We thus recommend these three feature analysis approaches, along with the original angular response curves, for future similar studies.

  • Reliable marine benthic habitat maps at regional and national scales are needed to enable the move towards the sustainable management of marine environmental resources. The most effective means of developing broad-scale benthic habitat maps is to use commonly available marine physical data due to the paucity of adequate biological data and the prohibitive cost of directly sampling benthic biota over large areas. A new robust method of mapping marine benthic habitats at this scale was developed based on a stratified approach to habitat classification. This approach explicitly uses knowledge of marine benthic ecology to determine an appropriate number of stratification levels, to choose the most suitable environmental variables for each level, and to select ecologically significant boundary conditions (i.e. threshold values) for each variable. Three stratification levels, with nine environmental variables, were created using a spatial segmentation approach. Each level represents major environmental processes and characteristics of the Australian marine benthic environment. The finest scale of benthic habitat is represented by seafloor physical properties of topography, sediment grain size and seabed shear stress. Water-column nutrient parameters and bottom water temperature depicted the intermediate scale, while the broadest scale was defined by seabed insolation parameters derived from depth data. The classifications of the three stratified levels were implemented using an object-based fuzzy classification technique that recognises that habitats are largely homogenous spatial regions, and transitions between habitats are often gradual. Classification reliability was indicated in confidence maps. Physical habitat diversity was evaluated for the final benthic habitat map that combines the three classifications. The final benthic habitat map identifies the structurally complex continental shelf break as an area of relatively high habitat diversity. Continental Shelf Research

  • The biological data used in this study was collected by Museum Victoria in an extensive survey of the fauna of Bass Strait between 1979 and 1983. Additional sediment sampling and swath mapping of parts of Bass Strait were undertaken on GA Survey 226 and Australian Hydrographic Office Survey HI339, in which Geoscience Australia personnel participated (GA Survey 233). Survey HI339 also collected underwater video footage. Biological material from a range of taxonomic groups was identified as a basis for identification and analysis of biological communities. The results indicate that Bass Strait supports a particularly diverse fauna. A high degree of small-scale variation occurs, with even adjacent samples having low similarity. Video footage from sites to the east of Bass Strait corroborates the high degree of faunal diversity over small spatial scales. Analysis of physical variables, derived from data collected on the original survey and supplemented by more recent data, show that longitude and depth are important factors in explaining the biological diversity. Despite this, overall correlation of faunal composition with physical factors is poor, indicating that other environmental variables influence the composition of benthic assemblages, and that different groups of species react to different environmental variables. It is likely that the biota reflect a series of intergrading assemblages rather than a group of discrete and repeatable species associations. Sediment facies identified can be correlated with facies from the Otway margin (Boreen et al., 1993) and those mapped previously in Bass Strait (Jones and Davies, 1983). Analysis of sediments taken from sites previously targeted by Jones and Davies (1983) indicate that sampling technique has had little impact on retention of fines. Rather, the lack of fines is a reflection of the high energy environment of much of Bass Strait. Examination of the composition of sand and gravel fractions indicates that extensive bioerosion acts in concert with physical processes to produce carbonate mud. Biogenic content in sediments shows little correlation with living communities, due in part to the abundance of soft-bodied organisms in the biota, as well as the strong imprint of post-depositional processes on sediments. The biological patterns identified in this study broadly support the divisions of the current Interim Marine and Coastal Regionalisation of Australia (IMCRA Technical Group, 1998) for Bass Strait. However, the biological assemblages are not consistent enough to be mapped. The lack of relationships between biota and sediments over the scale of the study area may reflect the scale of the study area and limitations of the statistical analyses used.

  • Hyperspectral airborne images from the Eastern Fold Belt of the Mount Isa Inlier, were validated as new tool for the detection of Iron oxide Cu-Au (IOCG) related alteration. High resolution mineral maps derived from hyperspectral imaging (4.5m/pixel) enables the recognition of various types of hydrothermal alteration patterns and the localisation of fluid pathways. Four different types of hydrothermal alteration patterns were identified with the hyperspectral mineral maps: (1) Metasomatic 1: White mica mineral maps were applied to map the spatial distribution of regional sodic-calcic alteration in metasedimentary successions of the Soldiers Cap Group in the Snake Creek Anticline. (2) Metasomatic 2: Alteration zoning is evident from albitised granites, assigned to the Williams-Naraku Suite, along the Cloncurry Fault show characteristic absorption features in the shortwave infrared range (SWIR) and can be detected with white mica mineral maps (white mica composition, white mica content, white mica crystallinity index).

  • Multibeam sonars provide co-located high-resolution bathymetry and acoustic backscatter data over a swath of the seafloor. Not only does backscatter response vary with incidence angles but it also changes with different seabed habitat types as well. The resulting imagery depicts spatial changes in the morphological and physical characteristics of the seabed that many use to relate to other dataset such as biology and sediment data for seabed habitat classification purposes. As a co-custodian of national bathymetry data, Geoscience Australia holds massive volumes of multibeam data from various systems including comprehensive collection from its own SIMRAD EM3002D multibeam sonar system. Consequently, Geoscience Australia is researching the application of acoustic backscatter data for seabed habitat mapping to assist with deriving an inventory of seabed habitats for Australia's marine jurisdiction. We present a procedure and a technique developed for our SIMRAD EM3002D multibeam sonar system to derive meaningful angular backscatter response curves. The ultimate goal of this excersie is to try to make use of the angular backscatter response curve that many believe is unique and is an intrinsic property of the seafloor for seabed habitat classification purposes. Adopting the technique intially developed by the Centre for Marine Science and Technology at Curtin University of Technology, Geoscience Australia has further improved these techniques to suits its own sonar system. Issues surrounding the production of the angular backscatter response curves and their solutions will be discussed. We also present results derived from multibeam data acquired in the Joseph Bonaparte Gulf, NT and from the Carnarvorn Shelf (Point Cloates), WA from aboard AIMS Research Vessel Solander. This includes potential use of the angular backscatter response curves for seabed classification and results from a simple analysis using the Kolmogrov-Smirnov goodness of fit.