Tropical Cyclone (TC) Tracy impacted Darwin early on Christmas Day, 1974. The magnitude of damage was such that Tracy remains deeply ingrained in the Australian psyche. Several factors contributed to the widespread damage, including the intensity of the cyclone and construction materials employed in Darwin at the time. Since 1974, the population of Darwin has grown rapidly, from 46,000 in 1974 to nearly 115,000 in 2006. If TC Tracy were to strike Darwin in 2008, the impacts could be catastrophic. We perform a validation of Geoscience Australia's Tropical Cyclone Risk Model (TCRM) to assess the impacts TC Tracy would have on the 1974 landscape of Darwin, and compare the impacts to those determined from a post-impact survey. We then apply TCRM to the present-day landscape of Darwin to determine the damage incurred if a cyclone identical to TC Tracy impacted the city in 2008. In validating TCRM against the 1974 impact, we find an underestimate of the damage at 36% of replacement cost (RC), compared the survey estimate of 50-60% RC. Some of this deficit can be accounted for through the effects of large debris. Qualitatively, TCRM can spatially replicate the damage inflicted on Darwin by the small cyclone. The northern suburbs suffer the greatest damage, in line with the historical observations. For the 2008 scenario, TCRM indicates a nearly 90% reduction in the overall loss (% RC) over the Darwin region. Once again, the spatial nature of the damage is captured well, with the greatest damage incurred close to the eye of the cyclone. Areas that have been developed since 1974 such as Palmerston suffer very little damage due to the small extent of the severe winds. The northern suburbs, rebuilt in the years following TC Tracy, are much more resilient, largely due to the influence of very high building standards put in place between 1975 and 1980.

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).

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.

The Early Cretaceous Gage Sandstone and South Perth Shale formations are a prospective reservoir-seal pair in the Vlaming Sub-basin. Plays include post-breakup pinch-outs in the Gage Sandstone with the South Perth Shale forming top seal. The Gage reservoir has porosities of 18-25% and permeabilities of 1-1340 mD. It was deposited in palaeotopographic lows of the Valanginian breakup unconformity and is the lowstand component of the thick deltaic South Perth (SP) Supersequence. To characterise the reservoir-seal pair, a detailed sequence stratigraphic analysis was conducted by integrating 2D seismic interpretation, well log analysis and new biostratigraphic data. Palaeogeographic reconstructions for the SP Supersequence were derived from mapping higher-order prograding packages and establishing changes in sea level and sediment supply. Higher resolution Gage reservoir reconstructions were based on seismic facies mapping. The Gage reservoir forms part of a sand-rich submarine fan system similar to model proposed by Richards et al (1998). It ranges from canyon confined inner fan deposits to middle fan deposits on a basin plain. Directions of sediment supply are complex, with major sediment contributions from a northern and southern canyon adjacent to the Badaminna Fault Zone. The characteristics of the SP Supersequence differ markedly between the northern and southern parts of the sub-basin due to variations in palaeotopography and sediment supply. Palaeogeographic reconstructions reveal a series of regressions and transgressions leading to infilling of the palaeo-depression. Palaeogeographic reconstructions for the SP Supersequence portray a complex early post-rift depositional history in the central Vlaming Sub-basin. The developed approach is applicable for detailed studies of other sedimentary basins. APPEA

An extensive AEM survey recently commissioned by Geoscience Australia involved the use of two separate SkyTEM helicopter airborne electromagnetic (AEM) systems collecting data simultaneously. In order to ensure data consistency between the two systems, we follow the Danish example (conceived by the hydrogeophysics group from Aarhus University) of using a hover test site to calibrate the AEM data to a known reference. Since 2001, Denmark has employed a national test site for all electromagnetic (EM) instruments that are used there, including the SkyTEM system. The Lyngby test-site is recognised as a well-understood site with a well-described layered-earth structure of 5 layers. The accepted electrical structure model of the site acts as the reference model, and all instruments are brought to it in order to produce consistent results from all EM systems. Using a ground-based time-domain electromagnetic (TEM) system which has been calibrated at the Lyngby test site, we take EM measurements at a site selected here in Australia. With sufficient information of the instrument, we produce a layered-earth model that becomes the reference model for the two AEM systems used in the survey. We then bring the SkyTEM systems to the hover site and take soundings at multiple altitudes. From the hover test data and the ground based model, we calculate an optimal time shift and amplitude scale factor to ensure that both systems are able reproduce the accepted reference model. Conductivity sections produced with and without calibration factors show noticeably different profiles.

Three seismic lines (10GA-CP1, 10GA-CP2 and 10GA-CP3), which cross north to south across the Capricorn Orogen of Western Australia, have recently been collected by Geoscience Australia, ANSIR and the Geological Survey of Western Australia. The interpretation of these seismic lines is aimed at providing insight into the geologic structure of the Capricorn Orogen and to explore the relationship between the Pilbara and Yilgarn cratons. To aid in further interpretation and to add value to the seismic data an analysis of the available potential field data (gravity and magnetics) has also been undertaken. A range of geophysical data analysis techniques have been applied and include: multi-scale edge detection (worms), forward modelling and 3D inversion. By applying all three analysis techniques to the potential-field data major trends, contrasting properties and regional blocks relating to the subsurface geology have been determined, in turn, allowing for a detailed comparison with the seismic interpretation. Note that all results referred to in this abstract are preliminary and subject to change.

This document describes a format of the PRISM (Panchromatic Remote sensing Instrument for Stereo Mapping ) products generated by the ALOS data processing subsystem.

This document describes a format of the AVNIR-2 (Advanced Bisible Near-Infrared Radiometer) products generaged by the ALOS Data Processing Subsystem.