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The Carnarvon shelf at Point Cloates, Western Australia, is characterised by a series of prominent ridges and hundreds of mounds that provide hardground habitat for coral and sponge gardens. The largest ridge is 20 m high, extends 15 km alongshore in 60 m water depth and is interpreted as a drowned fringing reef. To landward, smaller ridges up to 1.5 km long and 16 m high are aligned to the north-northeast and are interpreted as relict aeolian dunes. Mounds are less than 5 m high and may also have a sub-aerial origin. In contrast, the surrounding seafloor is sandy with relatively low densities of epibenthic organisms. The dune ridges are estimated to be Late Pleistocene in age and their preservation is attributed to cementation of calcareous sands to form aeolianite, prior to the postglacial marine transgression. On the outer shelf, sponges grow on isolated low profile ridges at ~85 m and 105 m depth and are also interpreted as partially preserved relict shorelines.

Geoscience Australia has more than 50 years experience in the acquisition of deep crustal onshore seismic data, beginning with analogue low-fold explosive data, progressing through digital explosive data, and finally, in the last 12 years, moving into the digital vibroseis era. Over the years, shot data in a variety of formats has been recovered from a variety of media, both in-house and by external contractors. Processing through to final stack stage was used as a QC tool for transcription of some of the older analogue surveys, and proved so successful that the reprocessed data was released for interpretation. In other cases, more recent digital explosive surveys have benefited from reprocessing using modern processing algorithms. Key modules in Paradigm Geophysical's Disco/Focus software used by Geoscience Australia for reprocessing old data include refraction statics, spectral equalisation, stacking velocity analysis, surface consistent automatic residual statics and coherency enhancement. Coherency enhancement is commonly carried out on both NMO corrected shots and stack sections, with several iterations of NMO and autostatics. With the irregular offset distribution and low fold of legacy explosive data, dip moveout (DMO) correction is not possible, but due to the shorter spreads is not as critical as for modern high fold vibroseis data. Nevertheless, 'poor man's DMO' has proved successful in the shallow section, by the simple expedient of omitting 25% of the traces with the longest offsets.

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.

Single-copounds carbon isotops of Precambrian eviporates.

Severe wind has major impacts on exposed human settlements and infrastructure, while climate change is expected to increase the severe wind hazard in many regions of Australia. The Risk and Impact Analysis Group (RIAG) in Geoscience Australia (GA) has developed a series of techniques to analyse the impact of severe wind imposed on the residential buildings under current and future climate. The process includes four components: hazard, exposure, vulnerability and risk. Severe wind hazard represents site specific wind speed values for different return periods (e.g. 500-year, 2000-year return periods), which may be derived by the wind loading standard (AS/NZS 1170.2), or be a result of modelling for current or future climates. GA has developed a National Exposure Information System (NEXIS), a repository of spatial and structural information of infrastructure exposed and vulnerable to natural hazards. NEXIS has also been extended to consider the number of future residential structures by utilising simple spatial relationships. Using an expert evaluation process, GA has developed a series of fragility curves which relate wind speed to the expected level of damage to residential buildings (measured as a percentage of the total replacement cost) in specific regions in Australia. These curves include consideration of factors such as building location, age, roof material, wall material, and so on. Given a certain intensity of severe wind imposed on a certain type of residential building in a specific region, the physical impact to a community can be determined in terms of the economic loss and casualties. By applying above concepts and procedures, based on sample data from the selected cities, we have integrated these three components (hazard, residential buildings exposure and vulnerability) within a computational framework to derive severe wind risk under both current climate and for a range of climate scenarios. These processes will be utilised for the assessment of climate change adaptation strategies concerning structural wind loading.

Preliminary zircon data and tectonic framework for the Thomson Orogen, northwestern NSW

The global ocean absorbs 30% of anthropogenic CO2 emissions each year, which changes the seawater chemistry. The absorbed CO2 lowers the pH of seawater and thus causes ocean acidification. The pH of the global ocean has decreased by approximately 0.1 pH units since the Industrial Revolution, decreasing the concentration of carbonate ions. This has been shown to reduce the rate of biological carbonate production and to increase the solubility of carbonate minerals. As more CO2 is emitted and absorbed by the oceans, it is expected that there will be continuing reduction in carbonate production coupled with dissolution of carbonate sediments. This study was undertaken as part of a program to collect baseline data from Australia's seabed environments and to assess the likely impacts of ocean acidification on continental shelf sediments. Over 250 samples from four continental shelf areas of northern Australia (Capricorn Reef, Great Barrier Reef Lagoon, Torres Strait, Joseph Bonaparte Gulf) were analysed to characterise the surface sediment mineral and geochemical composition. Of particular importance was the quantification of carbonate minerals (calcite, aragonite, high-magnesium calcite) and the magnesium content in high-magnesium calcite. The latter determines the solubility of high-magnesium calcite, which is most soluble of all common carbonate minerals. The thermodynamic stability of carbonate minerals as referred to the state of saturation was calculated using the current and predicted equatorial ocean water composition [1]. Northern Australian continental shelf sediments are largely dominated by carbonate. High-magnesium calcite had the highest abundance of all carbonate minerals followed by aragonite in all areas. The average mol% MgCO3 in high-magnesium calcite varied from 13.6 to 15.5 mol% for the different areas, which is in agreement with the global average magnesium concentration in high-magnesium calcite in tropical and subtropical regions [2].

Workshop notes, includes "NDC in a box Virtual Appliance" software

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