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  • The Rayner Complex of East Antarctica is exposed between 45??80?E in the Enderby Land through Princes Elizabeth Land sector of East Antarctica. It is known to correlate with parts of present day India and to have been deformed and metamorphosed at high grades in the earliest Neoproterozoic (990-900 Ma). The age and origin of the protolith rocks of the Rayner Complex however remains largely unknown, as does the tectonic setting in which these rocks formed. New age data collected from the northern Prince Charles Mountains (eastern Rayner Complex), demonstrate that the pre-orogenic rocks from this region consist of: (1) volcanogenic and terrigenous sediments deposited between 1400 Ma and 1020 Ma in a magmatically active basin characterised by limited input from cratonic sources and, (2) probable syn-sedimentary granitoids dated to 1150 Ma. Our data confirm the continuity of the Rayner Complex into Prydz Bay, a region that preserves a remarkably similar geologic history but which is often differentiated from the Rayner Complex on the basis of a higher grade early Cambrian (~520 Ma) overprint. On the basis of our data we further conclude that the Rayner Complex protoliths likely in formed in a back-arc system that existed along the margin of the pre-Gondwana Indian craton. Anticlockwise P-T paths and high-T, low-P metamorphism associated with the inversion of the Rayner back-arc (990-900 Ma) suggest this event resulted from the accretion of a number of independent microplates, rather than continent-continent collision.

  • My First Record

  • The Australian Government formally releases new offshore exploration areas at the annual APPEA conference. In 2012, twenty-seven areas in nine offshore basins are being released for work program bidding. Closing dates for bid submissions are either six or twelve months after the release date, i.e. 8 November 2012 and 9 May 2013, depending on the exploration status in these areas and on data availability. As was the case in 2011, this year's Release again covers a total offshore area of about 200,000 km2. The Release Areas are located in Commonwealth waters offshore Northern Territory, Western Australia, South Australia, Victoria and Tasmania (Figure 1). Areas on the North West Shelf feature prominently again and include underexplored shallow water areas in the Arafura and Money Shoal basins and rank frontier deep water areas in the outer Browse and Roebuck basins as well as on the outer Exmouth Plateau. Following the recent uptake of exploration permits in the Bight Basin (Ceduna and Duntroon sub-basins) Australia's southern margin is well represented in the 2012 Acreage Release. Three new blocks in the Ceduna Sub-basin, four blocks in the Otway Basin, one large block in the Sorell Basin and two blocks in the eastern Gippsland Basin are on offer. Multiple industry nominations for this Acreage Release were received, confirming the healthy status of exploration activity in Australia. The Australian government continues to support these activities by providing free access to a wealth of geological and geophysical data.

  • The southwest margin is a complex and relatively poorly studied part of Australia's offshore continental region and includes the Southern Carnarvon, Perth and Mentelle basins, as well as the Naturaliste and Wallaby plateaus. A series of seismic profiles are interpreted, in conjunction with potential field data, to reassess the nature of the continent-ocean boundary (COB) across the region. Results highlight how the structural architecture of the margin varies significantly along strike according to the following criteria: a) the relative orientation of the margin with respect to the initial extension direction, b) the nature and extent of break-up related magmatism and c) the nature and width of the continent-ocean transition zone. Margin segmentation is directly linked to the location of major oceanic fracture zones as well as to the location and geometry of the major Palaeozoic to Mesozoic basins. Furthermore, the correlation between margin segmentation and structural trends of underlying Proterozoic Pinjarra Orogen suggests some basement control on margin evolution. The revised COB interpretation is combined with recent Indian Ocean plate reconstructions incorporating potential field data from the abyssal plains of west Australia and east Antarctica, including the Early Cretaceous southwest Australian margin. Comparisons between this model and recent basin scale sequence stratigraphic studies across the region provide new insights into Mesozoic basin evolution, including the relative timing of break-up within each basin. In addition, the model illustrates the possible impacts of Valanginian to Aptian transform margin development on the tectonic and thermal evolution of the northern Perth Basin depocentres.

  • In ecology, a common form of statistical analysis relates a biological variable to variables that delineate the physical environment, typically by fitting a regression model or one of its extensions. Unfortunately, the biological data and the physical data are frequently obtained from eparate sources of data. In such cases there is no guarantee that the biological and physical data are co-located and the regression model cannot be used. A common and pragmatic solution is to predict the physical variables at the locations of the biological variables and then to use the predictions as if they were observations.We show that this procedure can cause potentially misleading inferences and we use generalized linear models as an example. We propose a Berkson error model which overcomes the limitations. The differences between using predicted covariates and the Berkson error model are illustrated by using data from the marine environment, and a simulation study based on these data.

  • The Cadastral dataset is the spatial representation of property boundaries and descriptions in the Barcaldine, Charters Towers, Flinders, Longreach and Winton local government areas. It is a fundamental reference layer for spatial information systems in Queensland. This is a complete extract from the Digital Cadastral Database (DCDB). Updates to this cadastre in 2012 will be released on the following dates: January 15 and 29 - February 12 and 26 - March 11 and 25 - April 8 and 22 - May 6 and 20 - June 3 and 17 - July 1, 15 and 29 August 12 and 26 - September 9 and 23 - October 7 and 21 - November 4 and 18 - December 2, 16 and 30. In 2013 the 1st release date will be January 13.

  • After CO2 is injected into the saline aquifer, the formation water inside the porous media becomes more acidic. This will significantly affect the original chemical equilibrium underground, and induce or speed up various processes of dissolution and precipitation depending on the reservoir pressure, temperature and salinity of formation water. The Early Cretaceous Gage Sandstone has been identified as a potential reservoir unit suitable for large-scale CO2 storage in the offshore southern Perth Basin. This study assesses the contribution of mineralisation trapping to CO2 storage capacity of the Gage Sandstone through a comprehensive geochemical modelling.

  • The digital elevation model (DEM) grid covers the whole of the Cocos (Keeling) Islands. It was provided by AAM in 1km by 1km tiles which were then joined together using ESRI ArcMap. Each grid cell (1m x 1m) contains the height, in metres, of the ground surface derived from the 2011 LiDAR aerial survey data.

  • Note: A more recent version of this product is available. This dataset contains the high voltage electricity transmission lines that make up the electricity transmission network in Australia. For government use only. Access through negotiation with Geoscience Australia

  • 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.