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  • Initial lead isotope ratios from Archean volcanic-hosted massive sulfide (VHMS) and lode gold deposits and neodymium isotope model ages from igneous rocks from the geological provinces that host these deposits identify systematic spatial and temporal patterns, both within and between the provinces. The Abitibi-Wawa Subprovince of the Superior Province is characterized by highly juvenile lead and neodymium. Most other Archean provinces, however, are characterized by more evolved isotopes, although domains within them can be characterized by juvenile isotope ratios. Metal endowment (measured as the quantity of metal contained in geological resources per unit surface area) of VHMS and komatiite-associated nickel sulfide (KANS) deposits is related to the isotopic character, and therefore the tectonic history, of provinces that host these deposits. Provinces with extensive juvenile crust have significantly higher endowment of VHMS deposits, possibly as a consequence of higher heat flow and extension-related faults. Provinces with evolved crust have higher endowment of KANS deposits, possibly because such crust provided either a source of sulfur or a stable substrate for komatiite emplacement. In any case, initial radiogenic isotope ratios can be useful in predicting the endowment of Archean terranes for VHMS and KANS deposits. Limited data suggest similar relationships may hold in younger terranes.

  • Extensive benefits and tools can be gained for mineral explorers, land-users and government and university researchers using new spectral data and processing techniques. Improved methods were produced as part of a large multi-agency project focusing on the world-class Mt Isa mineral province in Australia. New approaches for ASTER calibration using high-resolution HyMap imagery through to testing for compensation for atmospheric residuals, lichen and other vegetation cover effects have been included in this study. . Specialised data processing software capable of calibrating and processing terabytes of multi-scene imagery and a new approach to delivery of products, were developed to improve non-specialist user interpretation and comparison with other datasets within a GIS. Developments in processing and detailed reporting of methodology, accuracies and applications can make spectral data a more functional and valuable tool for users of remote sensing data. A highly-calibrated approach to data processing, using PIMA ground samples to validate the HyMap, and then calibrating the ASTER data with the HyMap, allows products to have more detailed reliable accuracies and integration with other data, such as geophysical and regolith information in a GIS package, means new assessments and interpretations can be made in mapping and characterising materials at the surface. Previously undiscovered or masked surface expression of underlying materials, such as ore-deposits, can also be identified using these methods. Maps and products made for this project, covering some ~150 ASTER scenes and over 200 HyMap flight-lines, provide a ready-to-use tool that aids explorers in identifying and mapping unconsolidated regolith material and underlying bedrock and alteration mineralogy.

  • Land cover data are an essential input into a wide array of models including land surface process models and weather/climate models. The Dynamic Land Cover Dataset is the first nationally consistent and thematically comprehensive land cover reference for Australia. It provides a basis for reporting on change and trends in vegetation cover and extent. The Dynamic Land Cover Dataset Version 2 is a suite of of ISO (ISO 19144-2) compliant land cover maps across the Australian landmass. The series of maps presents land cover information for every 250m by 250m area of the country for rolling two year intervals from 2001. Each map has been generated by applying a sophisticated time series analysis technique known as Dynamic Markov Chain modeling to two years of MODIS Enhanced Vegetation Index (EVI) data. The Dynamic Markov Chain modeling was used to classify each pixel based on the way that pixel has behaved over a two year period. The maps contain 33 land cover classes which reflect the structural character of vegetation, ranging from cultivated and managed land covers (crops and pastures) to natural land covers such as closed forest and open grasslands. The series of maps have been compared with over 30,000 independent ground data points provided by State, Territory and Federal Government agencies. The sequence of maps shows how Australian land cover is changing over time.

  • The formation of iron oxide copper-gold (IOCG) deposits requires the conjunction in time and space of four essential components of the ore-forming mineral system: (1) energy source(s) to motivate the flow of hydrothermal fluids; (2) sources of ore components (metals, sulphur) and fluids; (3) favourable 'architecture' of permeable pathways for fluids, and (4) physico-chemical gradient sites for ore deposition. These components have been identified for IOCG systems in northern Queensland and South Australia, focussing on uranium-bearing IOCG deposits, during multidisciplinary studies of the energy potential of these regions. Each of the four system components was mapped using existing and newly acquired geological, geophysical and geochemical data. Using mineral potential modelling based on established approaches, maps of potential for uranium-bearing IOCG deposits (and for other uranium mineral systems) were created for each of the two regions. In north Queensland the under-cover extensions of the IOCG province hosted by the Mt Isa Eastern Succession were identified as highly prospective for IOCG deposits, although the potential for uranium-bearing systems appears to be more limited due to the relatively deep crustal levels of exposure. Potential for Paleozoic IOCG systems was also identified in the Etheridge Province. In South Australia the well known early Mesoproterozoic Olympic IOCG Province in the eastern Gawler Craton is proposed to extend westwards via the Mt Woods Inlier into the Coober Pedy Ridge region. A key result is the identification of IOCG potential in the northern Curnamona Province, of equivalent age and setting to that in the Gawler Craton

  • In this study, airborne electromagnetics (AEM), high resolution LiDAR, and drilling (100 bores) were acquired to map and assess groundwater resources and managed aquifer recharge options in the River Darling Floodplain. Neotectonic faulting and uplift has previously been described along the north-western margin of the Murray Basin along the adjacent Darling Lineament, however no evidence of neotectonics had previously been identified in the study area. Initial inversions of the AEM data revealed a multi-layered conductivity structure broadly consistent with the hydrostratigraphy identified in drilling. However, initial laterally and spatially constrained inversions showed only moderate correlations with ground data in the near-surface (~20m). As additional information from drilling and ground and borehole geophysical surveys became available, various horizontal and vertical constraints were trialled using a new Wave Number Domain Approximate Inversion procedure with a 1D multi-layer model and constraints in 3D. The resultant 3D conductivity model revealed that an important Pleistocene aquitard (Blanchetown Clay) confining the main aquifer of interest (Calivil Formation), has an undulating surface, which is locally sharply offset. An interpreted top surface suggests that it has been affected by significant warping and faulting, as well as regional tilting due to basin subsidence or margin uplift. Overall, the top surface of the Blanchetown Clay varies in elevation by 60m. Many of the sharp offsets in the conductivity layers are coincident with lineaments observed in the LiDAR data, and with underlying basement faults mapped from airborne magnetic data. The identification of neotectonics in this area was made possible through the acquisition of high resolution AEM data, and the selection of appropriate horizontal and vertical constraints in inversion procedures. Recognition of faulting in the unconsolidated sedimentary sequence helps explain the rapid recharge of underlying Pliocene aquifers, with neotectonics recognised as a key component of the hydrogeological conceptual model.

  • This collaborative project between Geoscience Australia (GA) and CSIRO aims to use physicochemical measurements, collected from surface overbank sediments as part of the National Geochemical Survey of Australia (NGSA) project, to help validate the ASTER multispectral geoscience maps of Australia. Both data sets have common information including that related to the surface abundance of silica, aluminium, iron, clay, sand and volatiles (including carbonate). The ASTER geoscience maps also provide spatial information about trends of mineral composition, which are potentially related to pH and oxidation state.

  • The term "Smartline" refers to a GIS line map format which can allow rapid capture of diverse coastal data into a single consistently classified map, which in turn can be readily analysed for many purposes. This format has been used to create a detailed nationally-consistent coastal geomorphic map of Australia, which is currently being used for the National Coastal Vulnerability Assessment (NCVA) as part of the underpinning information for understanding the vulnerability to sea level rise and other climate change influenced hazards such as storm surge. The utility of the Smartline format results from application of a number of key principles. A hierarchical form- and fabric-based (rather than morpho-dynamic) geomorphic classification is used to classify coastal landforms in shore-parallel tidal zones relating to but not necessarily co-incident with the GIS line itself. Together with the use of broad but geomorphically-meaningful classes, this allows Smartline to readily import coastal data from a diversity of differently-classified prior sources into one consistent map. The resulting map can be as spatially detailed as the available data sources allow, and can be used in at least two key ways: Firstly, Smartline can work as a source of consistently classified information which has been distilled out of a diversity of data sources and presented in a simple format from which required information can be rapidly extracted using queries. Given the practical difficulty many coastal planners and managers face in accessing and using the vast amount of primary coastal data now available in Australia, Smartline can provide the means to assimilate and synthesise all this data into more usable forms.

  • The under-explored deepwater Otway and Sorell basins lie offshore of southwestern Victoria and western Tasmania in water depths of 100-4,500 m. The basins developed during rifting and continental separation between Australia and Antarctica from the Cretaceous to Cenozoic and contain up to 10 km of sediments. Significant changes in basin architecture and depositional history from west to east reflect the transition from a divergent rifted continental margin to a transform continental margin. The basins are adjacent to hydrocarbon-producing areas of the Otway Basin, but despite good 2D seismic data coverage, they remain relatively untested and their prospectivity is poorly understood. The deepwater (>500 m) section of the Otway Basin has been tested by two wells, of which Somerset 1 recorded minor gas shows within the Upper Cretaceous section. Three wells have been drilled in the Sorell Basin, where minor oil and gas indications were recorded in Maastrichtian rocks near the base of Cape Sorell 1. Building on previous GA basin studies and using an integrated approach, new aeromagnetic data, open-file potential field, seismic and exploration well data have been used to develop new interpretations of basement structure and sedimentary basin architecture. Analysis of potential field data, integrated with interpretation of 2D seismic data, has shown that reactivated north-south Paleozoic structures, particularly the Avoca-Sorell Fault System, control the transition from extension through transtension to a dominantly strike-slip tectonic regime along this part of the southern margin. Depocentres to the west of this structure are large and deep in contrast to the narrow elongate depocentres to its east. Regional-scale mapping of key sequence stratigraphic surfaces across the basins has resulted in the identification of distinct basin phases. Three periods of upper crustal extension can be identified. In the north, one phase of extension in the Early Cretaceous and two in the Late Cretaceous can be mapped. However, to the south, the Late Cretaceous extensional phase extends into the Paleocene, reflecting the diachronous break-up history. Extension was followed by thermal subsidence, and during the Eocene-Oligocene the basin was affected by several periods of compression, resulting in inversion and uplift. The new seismic interpretation shows that depositional sequences hosting active petroleum systems in the producing areas of the Otway Basin are also likely to be present in the southern Otway and Sorell basins. Petroleum systems modelling suggests that if the equivalent petroleum systems elements are present, then they are mature for oil and gas generation, with generation and expulsion occurring mainly in the Late Cretaceous in the southern Otway and northern Sorell basins and during the Paleocene in the Strahan Sub-basin (southern Sorell Basin). The integration of sequence stratigraphic interpretation of seismic data, regional structural analysis and petroleum systems modelling has resulted in a clearer understanding of the tectonostratigraphic evolution of this complex basin system. The results of this study provide new insights into the geological controls on the development of the basins and their petroleum prospectivity.