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  • The first edition ACE - Australian Continental Elements dataset is a GIS representation of the lithosphere fabrics of the Australian plate, interpreted from linear features and associated discontinuities in the gravity anomaly map of continental Australia (Bacchin et al., 2008; Nakamura et al., 2011) and the global marine gravity dataset compiled from satellite altimetry (Sandwell & Smith, 2009). It should be used in context with these input data sources, at scales no more detailed than the nominal scale of 1:5 000 000.

  • Since the early 2000s Geoscience Australia has been compiling new seamless national continental scale geological maps. The first edition of a seamless 1:1 000 000 scale surface geology map of Australia was released in 2008 [1] and the latest edition released in 2012 [2]. This work draws extensively from available geological mapping in Australia, primarily at the scales of 1:250 000 and 1:100 000 with the addition of some special regional scale maps. The digital GIS dataset is linked to other national geoscience databases at Geoscience Australia, including the Australian Stratigraphic Units Database. In September 2013, Geoscience Australia released the first national Geological Provinces dataset [3]. Geoscience Australia's Geological Provinces Database captures detailed information such as age, stratigraphy, lithology, mineral resources, and relations to other provinces. It also captures outlines of the full (ie, concealed) extent and outcropping extent of a province. As part of Geoscience Australia's contribution to Searching the Deep Earth [4], current continental scale digital geological mapping in Geoscience Australia includes production of a new national bedrock geological map at 1:2 500 000 scale with stratigraphic units information that can be linked with other national geoscience databases, basement geology, and a national regolith landforms coverage. Looking ahead, a goal is to produce seamless, continental scale basement or 'solid' geology maps for a variety of depth/time slices. A recent step towards this goal has been the production of a map of Mesoproterozoic and older basement geology for a large region of central Australia, from the eastern Yilgarn Craton of Western Australia across the Musgrave and southern Arunta Provinces to the Queensland border.

  • 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.

  • 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.

  • The mechanism and uplift history of Australia's southeastern highlands has long been debated. End member models account for the topography as a down warped relict of an ancient plateau or a consequence of uplift associated with either rifting along the eastern margin or Cenozoic volcanism. All of these models assume present-day elevation is a consequence of isostatic equilibrium at the base of the crust. An analysis of the relationship between gravity and topography in the spectral domain shows the admittance at wavelengths longer than those controlled by flexure is ~50 mgal km-1. This value is characteristic of dynamic support arising from thermal anomalies beneath the plate predicted by multiple mantle convection simulations and observed over Africa, Antarctic and the Pacific Ocean. Division of long-wavelength filtered gravity by this admittance value suggests the southeastern highlands are supported by 400-900 m. The morphological expressions of this support are the Great Escarpment and major knick zones on rivers such as the Snowy. The temporal evolution of this support can be determined by exploiting longitudinal river profiles since their shape is controlled by uplift and modulated by erosion. By applying the well-known detachment limited stream power law to model erosion uplift histories can be extracted provided erosional parameters can be constrained. By calibrating the erosional parameters using incision rates along the Tumut River and Tumbarumba Creek as well as palaeoelevations of basalt flows the uplift history of the southeastern highlands can ascertained directly from the landscape. Our results show uplift of the southeastern highlands occurred in two phases associated with Cretaceous age rifting resulting in Tasman Sea floor spreading and Cenozoic volcanism. The latter event accounts for the observed amplitude of present-day dynamic topography thereby suggesting Cenozoic uplift occurred from an unperturbed isotactic elevation. Since Cretaceous rifting along the southeastern margin occurred over a cool mantle given the oldest oceanic floor is thinner than the global average it is unlikely that rift related uplift is a consequence of mafic underplating. The most likely driver for this earlier phase of uplift is emergence of eastern Australia from a dynamically drawdown position which has been inferred to explain the widespread mid-Cretaceous marine inundation of Eastern Australia. Therefore it is likely that both uplift events are controlled by changes in the thermal state of the mantle as opposed to changes in crustal thickness and density. This history of vertical motions is consistent with long-term river incision rates, basin sequence stratigraphy and thermochronological studies.

  • Tsunami inundation models provide fundamental information about coastal areas that may be inundated in the event of a tsunami. This information has relevance for disaster management activities, including evacuation planning, impact and risk assessment, and coastal engineering. A basic input to tsunami inundation models is a digital elevation model-that is, a model of the shape of the onshore environment. Onshore DEMs vary widely in resolution, accuracy, availability, and cost. Griffin et al. (2012) assessed how the accuracy and resolution of DEMs translate into uncertainties in estimates of tsunami inundation zones. The results showed that simply using the 'best available' elevation data, such as the freely available global SRTM elevation model, without considering data accuracy can lead to dangerously misleading results.

  • The Leeuwin Current has significant ecological impact on the coastal and marine ecosystem of south-western Australia. This study investigated the spatial and temporal dynamics of the Leeuwin Current using monthly MODIS SST dataset between July 2002 and December 2012. Topographic Position Index layers were derived from the SST data for the mapping of the spatial structure of the Leeuwin Current. The semi-automatic classification process involves segmentation, 'seeds' growing and manual editing. The mapping results enabled us to quantitatively examine the current's spatial and temporal dynamics in structure, strength, cross-shelf movement and chlorophyll a characteristic. It was found that the Leeuwin Current exhibits complex spatial structure, with a number of meanders, offshoots and eddies developed from the current core along its flowing path. The Leeuwin Current has a clear seasonal cycle. During austral winter, the current locates closer to the coast (near shelf break), becomes stronger in strength and has higher chlorophyll a concentrations. While, during austral summer, the current moves offshore, reduces its strength and chlorophyll a concentrations. The Leeuwin Current also has notable inter-annual variation due to ENSO events. In El Niño years the current is likely to reduce strength, move further inshore and increase its chlorophyll a concentrations. The opposite occurs during the La Niña years. In addition, this study also demonstrated that the Leeuwin Current has a significantly positive influence over the regional nutrient characteristics during the winter and autumn seasons.

  • Geoscience Australia (GA) is a leading promoter of airborne electromagnetic (AEM) surveying for regional mapping of cover thickness, under-cover basement geology and sedimentary basin architecture. Geoscience Australia flew three regional AEM surveys during the 2006-2011 Onshore Energy Security Program (OESP): Paterson (Western Australia, 2007-08); Pine Creek-Kombolgie (Northern Territory, 2009); and Frome (South Australia, 2010). Results from these surveys have produced a new understanding of the architecture of critical mineral system elements and mineral prospectivity (for a wide range of commodities) of these regions in the regolith, sedimentary basins and buried basement terrains. The OESP AEM survey data were processed using the National Computational Infrastructure (NCI) at the Australian National University to produce GIS-ready interpretation products and GOCADTM objects. The AEM data link scattered stratigraphic boreholes and seismic lines and allow the extrapolation of these 1D and 2D objects into 3D, often to explorable depths (~ 500 m). These data sets can then be combined with solid geology interpretations to allow researchers in government, industry and academia to build more reliable 3D models of basement geology, unconformities, the depth of weathering, structures, sedimentary facies changes and basin architecture across a wide area. The AEM data can also be used to describe the depth of weathering on unconformity surfaces that affects the geophysical signatures of underlying rocks. A number of 3D models developed at GA interpret the under-cover geology of cratons and mobile zones, the unconformity surfaces between these and the overlying sedimentary basins, and the architecture of those basins. These models are constructed primarily from AEM data using stratigraphic borehole control and show how AEM data can be used to map the cross-over area between surface geological mapping, stratigraphic drilling and seismic reflection mapping. These models can be used by minerals explorers to more confidently explore in areas of shallow to moderate sedimentary basin cover by providing more accurate cover thickness and depth to target information. The impacts of the three OESP AEM surveys are now beginning to be recognised. The success of the Paterson AEM Survey has led to the Geological Survey of Western Australia announcing a series of OESP-style regional AEM surveys for the future, the first of which (the Capricorn Orogen AEM Survey) completed acquisition in January 2014. Several new discoveries have been attributed to the OESP AEM data sets including deposits at Yeneena (copper) and Beadell (copper-lead-zinc) in the Paterson region, Thunderball (uranium) in the Pine Creek region and Farina (copper) in the Frome region. New tenements for uranium, copper and gold have also been announced on the results of these surveys. Regional AEM is now being applied in a joint State and Commonwealth Government initiative between GA, the Geological Survey of Queensland and the Geological Survey of New South Wales to assess the geology and prospectivity of the Southern Thomson Orogen around Hungerford and Eulo. These data will be used to map the depth of the unconformity between the Thomson Orogen rocks and overlying sedimentary basins, interpret the nature of covered basement rocks and provide more reliable cover thickness and depth to target information for explorers in this frontier area.

  • A general lack of exploration success in the offshore northern Perth Basin sheared margin has lead to a perception that the primary source rock onshore (Triassic Kockatea Shale Hovea Member) is absent or has limited generative potential. However, recent offshore well studies show the unit is present and oil prone. Multiple palaeo-oil columns were identified within Permian reservoirs below the Kockatea Shale seal. This prompted a trap integrity study into fault reactivation as a critical risk for hydrocarbon preservation. Breach of accumulations could be attributed to JurassicEarly Cretaceous extension, Valanginian breakup, margin tilt or localised Miocene inversion. This study focused on four prospects, covered by 3D seismic data, containing breached and preserved oil columns. 3D geomechanical modelling simulated the response of trap-bounding faults and fluid flow to Jurassic-Early Cretaceous NW-SE extension. Calibration of modelling results against fluid inclusion data, as well as current and palaeo-oil columns, demonstrates that along-fault fluid flow correlates with areas of high shear and volumetric strains. Localisation of deformation leads to both an increase in structural permeability promoting fluid flow, and the development of hard-linkages between reactivated Permian reservoir faults and Jurassic faults producing top seal bypass. The main structural factors controlling the distribution of permeable fault segments are: (i) failure of faults striking 350??110?N; (ii) fault plane intersections generating high shear deformation and dilation; and (iii) preferential reactivation of larger faults shielding neighbouring structures. These results point to a regional predictive approach for assessing trap integrity in the offshore northern Perth Basin. While this approach will help explorers reduce risk the study highlights the need to identify other play types that avoid fault seal breach. An as yet untested potential basin floor fan stratigraphic play in the Abrolhos Sub-basin and analogues to the successful Cretaceous stratigraphic traps along the West African sheared margin in the Zeewyck Sub-basin may satisfy these criteria.

  • 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.