Regolith carbonate or secondary carbonate is a key component of the regolith, particularly in many Mediterranean, arid and semi-arid regions of Australia. National maps of regolith carbonate distribution have been compiled from regional soil, regolith and geological mapping with varying degrees of confidence and consistency. Here we apply a decision tree approach based on a piecewise linear regression model to estimate and map the near-surface regolith carbonate concentration at the continental scale. The model is based on relationships established from the 1311 field sites of the National Geochemical Survey of Australia (NGSA) and 49 national environmental covariate datasets. Regolith carbonate concentration (weight %) was averaged from the <2 mm grain size-fractions of samples taken from two depth ranges (0-10 cm and ~60-80 cm) at each NGSA site. The final model is based on the average of 20 runs generated by randomly selecting 90% training and 10% validation splits of the input data. Results present an average coefficient of determination (R2) of 0.56 on the validation dataset. The covariates used in the prediction are consistent with our understanding of the controls on the sources (inputs), preservation and distribution of regolith carbonate within the Australian landscape. The model produces a continuous, quantitative prediction of regolith carbonate abundance in surficial regolith at a resolution of 90 m with associated estimates of model uncertainty. The model-derived map is broadly consistent with our current knowledge of the distribution of carbonate-rich soil and regolith in Australia. This methodology allows the rapid generation of an internally consistent and continuous layer of geoinformation that may be applicable to other carbonate-rich landscapes globally. The methodology used in this study has the potential to be used in predicting other geochemical constituents of the regolith.

Tide gauge data forms the basis for determining global or local sea level rise with respect to a global geocentric reference frame. Data from repeated precise levelling connections between the tide gauge and a series of coastal and inland benchmarks, including a Continuous GPS (CGPS) benchmark, is used to determine the stability of tide gauges at 12 locations in the South Pacific. The method for determining this is based on a constant velocity model which minimises the net movement amongst a set of datum benchmarks surveyed since the installation of the tide gauges. Tide gauges were found to be sinking, relative to the CGPS benchmark, in Pohnpei (FSM), Samoa, Vanuatu, Tonga, Nauru, Tuvalu, Fiji and Cook Is; listed in order of the sinking rate, with a maximum of -1.01 - 0.63 mm/yr at Pohnpei (FSM) and a minimum of -0.03 - 0.81mm/yr at Cook Is. The tide gauge was rising, relative to the CGPS benchmark, in Solomon Is, Manus Is (PNG), Kiribati and Marshall Is, with a maximum of 3.12 - 0.49mm/yr in Solomon Is and a minimum of 0.01 - 0.91mm/yr in Marshall Is. However, these estimates are unreliable for the Solomon Is and Marshall Is, which have recently established CGPS benchmarks and have been surveyed less than 3 times. In Tonga and Cook Is, the tide gauge was found to be disturbed or affected by survey errors whereas the Vanuatu results were affected by earthquakes. It was also found that the constant velocity model did not fit the observations at the tide gauges in Tonga, Cook Is, Fiji, Marshall Is and Vanuatu, which had large variations in their velocities. This is an indicator of the high frequency (short period) motion of the tide gauge structure, which cannot be measured by the levelling method since these have a higher frequency than the time interval between levelling surveys.

Discusses reasons to use the Australian Stratigraphic Units Database (ASUD), and new features of the web query page and reports

Cyclone Tracy is the only tropical cyclone to have devastated a major Australian population centre. Following the disaster (December 1974), the Australian Government implemented significantly improved building standards aimed at reducing the impact of a similar event in future. Geoscience Australia has developed models of severe wind risk for the Australian continent which utilise impact modelling, where we separately assess hazard, exposure and vulnerability in order to evaluate impact/damage. As often occurs in extreme natural disasters, meteorological instrumentation failed prior to the maximum wind gusts being recorded, so the spatial extent of the peak wind gusts were inferred from models constrained by estimates of the observed maximum peak wind gust. For this study, we utilise the wind vulnerability relationships determined in recent years for similar circa 1974 structures, and our knowledge of the type and specific location of structures at the time, to make the link between hazard and impact/damage. This spatial damage estimation (site specific values) is compared with the observed 1974 post-event survey damage in an effort to validate the model. As a result of Cyclone Tracy and the subsequent evacuation of 75% of the population, much more attention was given to building codes and other social aspects of disaster planning (i.e. tree planting). The likelihood of another severe cyclone impacting Darwin is real and on past experience likely within the next few decades. The study utilises both the exposure and vulnerability for 1974 and present-day residential building inventories, to evaluate the resulting effectiveness of the improved building codes. This provides a comparative impact assessment of the scenario were Cyclone Tracy to occur in the current cyclone season and evaluates the reduced vulnerability of the present building stock (compared to 1974). The study also assesses the effect that improved building standards have had on the Darwin community.

The world's first continental-scale Advanced Spaceborne Thermal Emissions and Reflectance Radiometer (ASTER) mosaic, and related mineral group maps for Australia, are being released at the 34th International Geological Congress. These products have 30 m pixel resolution across the continent and can be used to identify, map and characterise near-surface materials that are spatially and chemically associated with various types of ore deposits. For example, the ASTER maps show that the 200 km length of colluvial fans shedding eastward from the Northern Flinders Ranges comprise different mineralogical characteristics, presumably reflecting their provenance. Furthermore, the most eastward margins of these fans show patterns interpreted as being related to differences in the chemistry of the groundwaters migrating into the Lake Frome drainage system. Key ASTER products include the Opaque Index map which highlights reduced environments and, consequently, redox relationships; and the AlOH Group Composition map which indicates areas that are dominated by neutral-alkaline illitic/ smectitic soils in contrast to those comprising kaolinitic soils which form in more neutral-acid conditions. These mineral maps thus have the potential to assist exploration for uranium (mapping oxidised groundwater) and geothermal energy (tracing viable U-bearing source rocks/fluids and the associated active plumbing network).

Seismic interval velocities derived from stacking velocities can provide some clues to determination of rock lithology. This concept has been applied to understand the divergent dipping reflector (DDR) and seaward dipping reflector (SDR) packages over the Wallaby Plateau and Wallaby Saddle that were imaged on the 2008/2009 seismic survey GA310 contracted by Geoscience Australia. Root mean square velocities (Vrms) used to calculate interval velocities (Vint) were derived from long cable data. Vrms were picked on traces after pre-stack time migration, and the 4th order normal move-out (NMO) correction was implemented. Therefore, distortions to interval velocities due to insufficient curvature of NMO curve at short offsets, structural dip and ray bending due to stratification are assumed to be largely suppressed. Consequently Vrms velocities are assumed to approximate average velocities.

Marine physical and geochemical data can be valuable in predicting the potential distributions and assemblages of marine species, acting as surrogate measures of biodiversity. The results of surrogacy analysis can also be useful for identifying ecological processes that link physical environmental attributes to the distribution of seabed biota. This paper reports the results of a surrogacy study in Jervis Bay, a shallow-water, sandy marine embayment in south-eastern Australia. A wide range of high-resolution co-located physical and biological data were employed, including multibeam bathymetry and backscatter data and their derivatives, parameters that describe seabed sediment and water column physical characteristics, seabed exposure, and infauna species. The study applied three decision tree models and a robust model selection process. The results show that the model performance for three diversity indices and seven out of eight infauna species range from acceptable to good. Important surrogates for infauna diversity and species distributions within the mapped area are broad-scale habitat type, seabed exposure, sediment nutrient status, and seabed rugosity and heterogeneity. The results demonstrate that abiotic environmental parameters of a sandy embayment can be used to effectively predict infauna species distributions and biodiversity patterns. International Journal of Geographical Information Science

An igneous zircon reference material (OG1) was characterised for U-Pb isotopes by ID-TIMS, and utilised to evaluate SIMS (SHRIMP) instrumental mass fractionation (IMF) of radiogenic Pb isotopes (207Pb*/206Pb*). The TIMS 207Pb*/206Pb* reference value for OG1 was 0.29907 ± 0.00011 (95% confidence limit), 3465.4 ± 0.6 Ma. The high 207Pb* (~ 30 -g g-1), negligible common Pb, and isotopic homogeneity permitted precise (± 1-2) 207Pb*/206Pb* measurements within the analytical sessions. External reproducibility of mean 207Pb*/206Pb* ratios between sessions was demonstrated for one instrument, yielding a mean IMF of +0.87 ± 0.49. The mean 207Pb*/206Pb* ratios between instruments were dispersed beyond uncertainties, with session IMF values from +3.6 ± 1.7- to -2.4 ± 1.3, and a grand mean IMF value (twenty-six sessions) of +0.70 ± 0.52, indicating a tendency towards elevated 207Pb*/206Pb*. The specific causes of variability in IMF are unclear, but generally reflect subtle differences in analytical conditions. The common practice in SIMS of assuming that IMF for Pb+ is insignificant could result in systematic age biases and underestimated uncertainties, of critical importance for precise correlation of Precambrian events. Nevertheless, a zircon RM such as OG1 can be readily incorporated into routine dating to improve 207Pb*/206Pb* accuracy and external reproducibility.

The northern Australian continental shelf is the focus for an expanding offshore energy industry and is also recognised for its high-value marine biodiversity in regional marine management plans. To reduce uncertainty and risk in the future development and management of the region, Geoscience Australia has an ongoing program to provide integrated marine environmental information to support both activities. The program includes collation of existing marine data and acquisition of new high resolution datasets. In 2009 and 2010, marine surveys in eastern Joseph Bonaparte Gulf were completed to characterise the seabed in representative areas, assess potential for geohazards and identify unique or sensitive benthic habitats. Data acquired included multibeam sonar bathymetry (~1900 km2), shallow (<120 m) sub-bottom profiles, sediment grabs and shallow (2-5 m) cores, towed video and epibenthic sleds. Geomorphic features mapped range from expansive soft-sediment plains, to isolated carbonate banks that rise tens of metres and incised valleys up to 200 m deep. Each feature is characterised by a distinctive biota, ranging from coral and sponge gardens on banks to diverse infaunal communities across plains. Geohazards include potential for localised slumping in valleys and escape of subsurface fluid/gas from plains and valley floors. To facilitate uptake of this information, results are integrated as generalised graphical models representing key spatial patterns of shelf ecosystems. This work has led to further work in targeted areas of the Gulf as part of a new four-year Australian Government program to inform geological and environmental assessments of offshore basins for CO2 storage.

Severe wind damage accounts for about 40 percent of the total building damage observed in Australia during the 20th century. Climate change has the potential to significantly affect severe wind hazard and the resulting level of loss. W report on a nationally consistent assessment of severe wind hazard across the Australian continent, and also severe wind risk to residential houses (quantified in terms of annualised loss). A computational framework has been developed to quantify both the wind hazard and risk due to severe winds, based on innovative modeling techniques and application of the National Exposure Information System (NEXIS). A combination of tropical cyclone, synoptic and thunderstorm wind hazard estimates is used to provide a revised estimate of the severe wind hazard across Australia. The hazard modeling utilises both 'current climate' information and also simulations forced by IPCC SRES climate change scenarios (employed to estimate how the wind hazard may be influenced by climate change). Our analysis has identified regions where the design wind speed depicted in the Australian/New Zealand Wind Loading Standard (AS/NZS 1170.2, 2010) is lower than 'new' hazard analysis. In considering future climate scenarios, four case study regions are used to illustrate when the wind loading standard may be inadequate, and where retrofitting is indicated as a viable adaptation option at either the present or at a specified future time. The comparison of current and projected future risk, currently only considers direct costs (structural damage to houses) associated with severe wind hazard. A broader assessment methodology is discussed.