This service has been created specifically for display in the National Map and the chosen symbology may not suit other mapping applications. The Australian Topographic web map service is seamless national dataset coverage for the whole of Australia. These data are best suited to graphical applications. These data may vary greatly in quality depending on the method of capture and digitising specifications in place at the time of capture. The web map service portrays detailed graphic representation of features that appear on the Earth's surface. These features include the administration boundaries from the Geoscience Australia 250K Topographic Data, including state forest and reserves.

Several belts of poorly-exposed igneous rocks occur in the Grampians-Stavely Zone of western Victoria, close to the interpreted Cambrian east Gondwana continental margin. Previous geochemical studies on the outcropping igneous rocks around Mount Stavely, Mount Dryden and in the Black Range have recognised characteristics similar to those found in modern magmatic arcs. These rocks are collectively considered to form part of a single Middle to Late Cambrian arc system, referred to as the Stavely Arc. While outcropping examples of the Stavely Arc magmas are well studied, the character of other (likely) arc-related rocks imaged by magnetic data beneath recent, thin cover has remained enigmatic. New geochemical data from a recent stratigraphic drilling program, together with analysis of rocks from government and industry drill holes has allowed for a more complete understanding of the Stavely Arc package. A range of rock associations have been recognised, including low-Ti boninite-like rocks, back-arc-related tholeiitic rocks, adakitic porphyry intrusives, serpentinites, and highly-depleted mafic to intermediate volcanics and intrusives. The majority of arc-related rocks comprise low- to high-K calc-alkaline basalt, andesite, dacite, and geochemically-related quartz diorite, which display similar N-MORB-normalised trace element patterns, LREE-enriched REE patterns and moderately evolved to weakly juvenile Nd isotopic compositions (Nd 500 Ma = -3.95 to +0.46). High-Al basalts intersected during stratigraphic drilling also show weakly-developed calc-alkaline compositions. However, these are distinguished from the other calc-alkaline rocks by higher Al2O3, N-MORB-like trace element patterns, relatively flat REE patterns and much more juvenile Nd isotopic compositions (Nd 500 Ma = +4.73 to +6.33). High-Al basalts are spatially associated with boninites intersected by mineral exploration drilling. The earliest geochronological evidence for Stavely Arc magmatism is provided by an isotopically juvenile felsic intrusive with an interpreted arc-related origin dated at ~510 Ma. This age is synchronous with tholeiitic dolerite from the western Grampians-Stavely Zone interpreted to have been emplaced in a back-arc extensional setting. Available ages for volcanic rocks of the Stavely Arc are only known from the Mount Stavely Belt, and show that arc magmatism reached maturity around ~505-500 Ma. Overall geochemical systematics suggest that the majority of calc-alkaline rocks of the Stavely Arc have affinities with modern island arcs with (limited) continental crust involvement. It is unlikely that the thickness of any pre-existing Precambrian crust was great, given the Nd isotopic compositions and lack of inherited Mesoproterozoic or older zircons. In comparison, the more juvenile isotopic characteristics, weakly-developed subduction-related features, and spatial association with boninites of the high-Al basalts are more consistent with a more primitive arc setting, and may represent an (early?) phase of Stavely Arc magmatism in which there was insignificant crustal involvement. Similar geochemical characteristics, ages, and inferred tectonic setting are consistent with the Stavely Arc forming part of a larger Middle to Late Cambrian arc system that also includes the Mount Wright Arc in New South Wales and the Jamison Volcanic Group (Selwyn Block) in central Victoria.

Short abstract for 35th International Geological Congress, Capetown, South Africa, August/September 2016

Airborne electromagnetic (AEM) data are an immensely useful tool for mapping cover thickness and under cover geology in Australia. The regional AEM surveys conducted by Geoscience Australia (GA) are an ideal starting point for integrating legacy AEM datasets across a range of scales with other information, e.g. borehole stratigraphy and shallow seismic data, to add to a national cover thickness map. Geoscience Australia is working towards this end as part of the UNCOVER Initiative.

Geoscience Australia and the CO2CRC operate a controlled release facility in Canberra, Australia, designed for simulating subsurface emissions of CO2 by injecting gas into a horizontal well. Three controlled release experiments were conducted at this site during 2012-2013, over 7-9 week periods, to assess and develop near-surface monitoring technologies for application to carbon dioxide geological storage sites (Feitz et al., 2014). A key well-established technique for characterizing surface CO2 emission sources from controlled release sites or natural CO2 seeps is soil flux surveys. The technique is often considered as the benchmark technique for characterizing a site's emissions or as a baseline for comparing other measurement techniques, but has received less attention with regards to its absolute performance. The extensive soil gas surveys undertaken during Release 1 (Feb-May 2012) and Release 3 (Oct-Dec 2013) are the subject of this paper. Several studies have highlighted factors which can have an effect on soil flux measurements, including meteorological influences such as air pressure and wind speed, which can increase or suppress soil fluxes (Rinaldi et al. 2012). Work at the Canberra controlled release site has highlighted the influence groundwater has on the spatial distribution of fluxes.). In addition, there are several different methods available for inverting soil flux measurements to obtain the emission rate of a surveyed area. These range in complexity from planar averaging to geostatistical methods such as sequential Gaussian simulation (Lewicki et al. 2005). Each inversion technique relies on its own subset of assumptions or limitations, which can also impact the end emissions estimate. Thus deriving a realistic estimate of the total emission rate will depend on both environmental forcing as well as the applied inversion method. An in-house method for soil flux interpolation has been developed and is presented. A cubic interpolated surface is generated from all the measurement points (Figure 1), from which a background linear interpolated surface is subtracted off, leaving the net leakage flux. The background surface is prepared by identifying all background points matching a certain criteria (for this release experiment distance from release well was used) and interpolating only over those points. In these experiments, soil flux surveys were collected on a predefined grid, using an irregular sampling pattern with higher density of samples nearer to the leak hotspots to provide higher spatial resolution in the regions where flux changes most rapidly (Figure 2). The same release rate of 144 kgCO2/day was used for both experiments. It was observed that the surface flux distribution shifts markedly between experiments, most likely a function of seasonal differences (2012 was wet; 2013 was dry) and resulting differences in groundwater depth, soil saturation and the extent of the vadose zone.. The depth to the groundwater measured at monitoring wells in proximity to the release well was 0.85-1.2 m during the 2012 (wet) release whereas it ranged from 1.9-2.3 m during the 2013 (dry) release experiment. The horizontal well is located 2.0 m below the ground surface. This paper explores the performance of soil flux surveys for providing an accurate estimate of the release rate, using a series of soil flux surveys collected across both release experiments. Emission estimates are generated by applying several common inversion methods, which are then compared to the known release rate of CO2. An evaluation as to the relative suitability of different inversion methods will be provided based on their performance. Deviations from the measured release rate are also explored with respect to survey design, meteorological and groundwater factors, which can lead and inform the future deployment of soil flux surveys in a monitoring and verification program.

The coverage of this dataset is over the WestNarranLake region . The C3 LAS data set contains point data in LAS 1.2 format sourced from a LiDAR ( Light Detection and Ranging ) from an ALS50 ( Airborne Laser Scanner ) sensor . The processed data has been manually edited to achieve LPI classification level 3 whereby the ground class contains minimal non-ground points such as vegetation, water , bridges , temporary features , jetties etc . Purpose: To provide fit-for-purpose elevation data for use in applications related to coastal vulnerability assessment, natural resource management ( especially water and forests) , transportation and urban planning . Additional lineage information: This data has an accuracy of 0.3m ( 95 CI ) vertical and 0.8m ( 95 CI ) horizontal with a minimum point density of one laser pulse per square metre . For more information on the datas accuracy, refer to the lineage provided in the data history .

Deep basement cores from petroleum and stratigraphic drill holes through central and southwest Queensland show that the subsurface Thomson Orogen is dominated by monotonous metasedimentary units but also includes scattered felsic volcanic rocks and more abundant (locally batholithic-scale) intrusions. These igneous rocks and small granitoid exposures along the Eulo Ridge provide means of probing the deeper crustal composition and the geological evolution of this vast area that is mostly covered by deep sedimentary basins.

Anthropogenic mercury (Hg) is a global pollutant capable of undergoing long-range atmospheric transport. Understanding biogeochemical controls on the spatial distribution of Hg in Australia at the continental scale with its unique biota, soil types, and climatic variables, is critical for modelling Hg emission rates and transport at regional and global scales. Surface (0-10 cm) catchment outlet sediment samples from the National Geochemical Survey of Australia (NGSA) were analysed for aqua regia soluble element content including Hg in coarse (<2 mm) and fine (<75 µm) grain-size fractions by ICP-MS analysis. We hypothesise that natural controls including soil type (organic carbon and clay content), vegetation type and climate variables (precipitation, temperature, evapotranspiration, solar radiation) explain the Hg variability at the continental scale in Australia. For this purpose, we are utilizing digital maps of the above-mentioned variables, and the NGSA continental-scale geochemical data to perform geostatistical modelling of Hg distribution at the continental scale. Our preliminary results indicate that organic carbon and selenium concentrations correlate with Hg concentrations in coastal landscapes in the cool and warm temperate bioclimatic zones of southern and eastern Australia across latitudinal and longitudinal gradients.

This abstract is for a keynote presentation at the 2016 Australian Earth Science Convention in Adelaide.

The nature of Archean tectonic processes, including the timing and nature of the transition from an early, potentially gravity-driven tectonic regime to a proto-plate tectonics, is still widely debated. With their high spatial resolution, deep seismic reflection images provide important constraints on geodynamic models of tectonic processes due to the apparent correlation between reflectors and strain fabrics. Following multi-year seismic acquisition programs in the Yilgarn craton by Geoscience Australia and the Geological Survey of Western Australia and in the Superior craton by the Canadian Lithoprobe program, these two cratons are now the best surveyed Archean regions on Earth. Integrated interpretation of seismic and geological data show that the Superior craton grew as various island arcs, oceanic plateaux, and micro-continental fragments of Meso-Neoarchean age were accreted to the southern margin of a pre-existing microcontinent (North Caribou superterrane) which gave rise to well-developed east-striking belts of granite-greenstone, metasedimentary, and plutonic rocks. These belts were crossed by the Lithoprobe Western Superior transect. The seismic reflection lines reveal a doubly-vergent orogen in the north, and in the south north-dipping mid-crustal reflection fabrics. The latter are interpreted to represent successive episodes of underthrusting, with Moho offsets locating relict suture zones. These north-dipping mid-crustal reflection fabrics, which are underlain by subhorizontal reflections in the lower crust, correspond to the 3.4-2.7 Ga Winnipeg River and 3.0-2.7 Ga Marmion terranes. The 2-3 s thick unit of subhorizontal reflections in the lower crust, which exhibits 8% azimuthal P wave anisotropy, has been interpreted as a subcreted slab of oceanic crust. The evolution of the Yilgarn craton is still strongly debated: One of the more prevalent theories interprets the NNE-trending granite-greenstone belts to reflect eastward growth of the craton by accretion to the eastern margin of a microcontinent comprising the Meso-Neoarchean Youanmi terrane. More recently, it has been proposed that these belts arose through repeated episodes of extension and contraction above a west-dipping subduction zone. The Youanmi terrane is characterized by an extensive fabric (> 500 km) of commonly listric east-dipping mid-crustal reflections that sole out into the upper part of a 2-3 s thick region of subhorizontal lower crustal reflections. This observed fabric is similar to that observed in the Marmion terrane, and it may be speculated that this fabric is a common characteristic of Mesoarchean crust. Originally interpreted as related to shortening, many mid-lower crustal seismic reflectors in the Yilgarn craton are now viewed as arising in an extensional setting, perhaps due to gravitational spreading. Given their similar geometry, the seismic reflectors in the Mesoarchean Marmion terrane may also have formed by a similar process prior to the terrane being caught up in the accretionary orogeny of the Western Superior craton. In this case, the lower crustal P wave anisotropy arose from ductile flow prior to collision, and the subhorizontal lower crustal reflection fabric does not represent a subcreted oceanic slab; in fact, the reflectors are most likely part of the Marmion terrane, making it thicker than previously thought. This study illustrates the usefulness of comparisons of seismic reflection data of different Archean cratons.