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].

The Garnaut Climate Change Review commissioned by Australia's State and Territory Governments examined the impacts of, and possible policy responses to, climate change on the Australian economy. This presentation discussed the methodology developed for the Review by Geoscience Australia and the outputs which provided an assessment of the impact of tropical cyclone (TC) hazard on communities in northern Australia. The study utilized predicted changes in the maximum potential intensity (MPI) to define changes in the wind hazard and storm surge potential. The MPI sets a thermodynamic, theoretical upper limit for the distribution of TC intensities for a given vertical temperature and humidity profile and a given location. Associated storm surge impacts were developed using a simple relationship between TC intensity and storm surge height and adopting the IPCC fourth assessment global mid-point sea-level rise predictions. We considered the impact on the residential building stock of severe wind and storm surge hazards associated with a number of IPCC climate change scenarios. Changes in residential building stock, for over 500 coastal statistical local areas (SLA's) from Southeast Queensland anticlockwise to Perth, were forecast using Australian Bureau of Statistics population projections through to 2100. A Probable Maximum Loss (PML) curve for each study region was obtained by considering the return-period hazard over the range from 50 to 5000 years. The average annual cost to the region due to tropical cyclones across this wide time period (5000 years), often referred to as the 'annualised loss', was evaluated for each SLA. Expressing the annualised loss as a percentage of total reconstruction demonstrates the intensity of the risk to a particular community, which is not so evident in simple dollar loss figures.

Crust predating 3.0 Ga within the Australian continent has previously been identified only in relatively restricted areas of the Yilgarn and Pilbara Cratons of Western Australia. Here we report the discovery of early Mesoarchean (~3150 Ma) rocks in the eastern Gawler Craton of South Australia. Rocks of broadly Mesoarchean age have been inferred by some authors to exist at depth beneath the Gawler Craton (Creaser and Fanning, 1993; Daly and Fanning, 1993), but no rocks of this age have been identified previously at the surface. The newly identified Mesoarchean granites and gneisses crop out across at least ~20 x 30 km and, on the basis of inherited zircon and Nd-isotopic compositions, are inferred to be present at depth beneath a region of at least ~1500 km2.

An orogenic cycle typically follows a sequence of events or stages. These are basin formation and magmatism during extension, inversion and crustal thickening during contractional orogenesis, and finally extensional collapse of the orogen. The Archaean granite-greenstone terranes of the Eastern Yilgarn Craton (EYC) record a major deviation in this sequence of events. Within the overall contractional stage, the EYC underwent a lithospheric-scale extensional event between 2665 Ma and 2655 Ma, resulting in changes to the entire orogenic system. These changes associated with regional extension include: the crustal architecture; greenstone stratigraphy; granite magmatism; thermo-barometry (PTt paths); and structure. Synchronous with these changes was the deposition of the first significant gold, and it is likely that the intra-orogenic extensional event was one of the critical factors in the region's world-class gold endowment.

The western margin of Australia comprises a number of frontier sedimentary basins that are largely under-explored and relatively poorly understood. As part of the Federal Government's Offshore Energy Security Program, Geoscience Australia undertook seismic and marine reconnaissance surveys across the region in late 2008-early 2009. Targeted dredge and video-grab sampling in the canyons incising the continental slope successfully recovered sedimentary rocks from the North Perth Basin, Cuvier Margin and Wallaby Plateau, thus providing significant new insights into the geological history and palaeogeography of the region. The Middle Jurassic to Early Cretaceous was a period of major tectonism along this margin as Jurassic rifting was followed by the final break-up of Greater India from Australia in the Valanginian. Subsequent thermal subsidence and continental margin flexure led to the deposition of Cretaceous to Recent sediments. The successful recovery of a rich palyniferous succession of Early Cretaceous siliciclastics represents the first biostratigraphic data for much of the region, as vast tracks of this margin have no borehole data and are true 'frontier' regions. The new palynological data shows a clear progression from pre-rift (Berriasian) terrestrial deposition through syn-rift to early post-rift (Valanginian-early Hauterivian) restricted marine sequences and finally a succession of inner to outer shelfal environments in the late post-rift phase (mid Hauterivian-early Albian). Abstract continues (does not fit within this field)

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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.

Map showing the Location of Montara in the Timor Sea on a background of the 2009 topographic abd bathymetry grid and petroleum leases.

Australia's National Geospatial Reference System (NGRS) is a continually evolving system of infrastructure, data, software and knowledge. The NGRS serves the broader community by providing an accurate foundation for positioning, and consequently all spatial data. The NGRS is administered by the Intergovernmental Committee on Surveying and Mapping (ICSM) and maintained by its Federal and State jurisdictions. Increasingly, the role of Global Navigation Satellite Systems (GNSS) in positioning has required the globalisation of national coordinate systems. In the early 1990's ICSM endorsed the adoption of the Geocentric Datum of Australia (GDA94) which was aligned to the International Terrestrial Reference Frame (ITRF) with a stated uncertainty of 30mm horizontally and 50mm vertically. Since that time crustal deformation and the demand for higher accuracies has resulted in GDA94 no longer adequately serving user requirements. ITRF has continued to evolve in accuracy and distribution to the extent that it now requires very accurate modelling of linear and non-linear crustal deformation. Even the Australia plate, which has long been considered to be rigid, is now considered to be deforming at levels detectable by modern geodesy. Consequently, infrastructure development programs such as AuScope have been implemented to ensure that crustal deformation can be better measured. The Auscope program also aims to improve the accuracy of the ITRF by contributing to the next generation of the Global Geodetic Observing System in our region. This approach will ensure that the ITRF continues to evolve and that Australia's NGRS is integrally connected to it with equivalent accuracies. Ultimately this will remove the need for National Reference Systems, with a globally homogenous and stable reference system (e.g., ITRF) being far more beneficial to society. This paper reviews Australia's contribution to GGOS and how this impacts on positioning in Australia.

The Australian continent is actively deforming at a range of scales in response to far-field stresses associated with plate margins, and buoyancy forces associated with mantle dynamics. On the smallest scale (101 km), fault-related deformation associated with far-field stress partitioning has modified surface topography at rates of up to ~100 m / Myr. This deformation is evidenced in the record of historical earthquakes, and in the pre-historic record in the landscape. Paleoseismological studies indicate that few places in Australia have experienced a maximum magnitude earthquake since European settlement, and that faults in most areas are capable of hosting potentially catastrophic earthquakes with magnitudes in excess of 7.0. New South Wales is well represented in terms of its pre-historic earthquake record. Seismogenic faulting in the last 5-10 million years is thought to be responsible for locally generating up to 200 m of the contemporary topographic relief of the Eastern Highlands. Faults west of Sydney belonging to the Lapstone Structural Complex, and faults beneath the greater Sydney region, have been demonstrated to be associated with infrequent damaging earthquakes. . Decisions relating to the siting and construction of the built environment should therefore be informed with knowledge of the local neotectonics.