As part of its program to define the extents of the Australian Legal Continental Shelf on the Kerguelen Plateau AGSO acquired over 5500 km of new seismic data including the first regional datasets over Elan Bank and in the Labuan Basin. This report presents results of a geological framework study carried out to underpin the Australias Law of the Sea claim on the Kerguelen Plateau. It provides an up to-date analysis of the stratigraphy, structure, geological evolution and petroleum prospectivity of the Kerguelen Plateau region taking into account recent ODP drilling, geological sampling, seismic reflection and refraction data, as well as potential field data.

In 2010 and 2011, the Australian Government released exploration acreage in the Perth, Mentelle and Southern Carnarvon basins off the southwest margin of Australia. This release was underpinned by two new marine geophysical surveys (GA-310 and GA-2476) that were conducted by Geoscience Australia in late 2008 and early 2009 as part of the Australian Government's Offshore Energy Security Program. These surveys acquired a range of pre-competitive geological and geophysical data that included seismic reflection, gravity, magnetic and swath bathymetry measurements, as well as seafloor dredge samples. The new surveys provided a total of about 26 000 line km of new gravity and magnetic data that add to existing data from around 150 previous marine surveys conducted off the southwest margin since 1960. This Record describes the integration and levelling of the new gravity and magnetic data with existing data, both offshore and onshore, to produce a unified gravity and magnetic dataset for use in constraining regional tectonics, basin structure and petroleum prospectivity. Levelling is a key step in processing ship-borne gravity and magnetic data. This process minimises the mistie errors at ship-track cross-overs that arise from factors such as positioning errors, instrument drift and lack of diurnal corrections to magnetic data. Without accounting for these cross-over errors, gridded data can be rendered un-interpretable by artefacts and distortions at line cross-overs.

AUSCAN (Australian Canyons), a major research expedition that investigated Australia's southern margin from southern Tasmania in the east to off Cape Leeuwin in the west, successfully completed its mission in March 2003. The investigation included multibeam swath-mapping, geophysical profiling, geological and biological sampling, as well as oceanographic measurements. The data were collected to support marine environmental planning and management, to help model the structural and sedimentological evolution of the margin, and to assist understanding the climatic, oceanographic and environmental changes that affected the region during the late Quaternary. Important objectives were to map in detail and study the geomorphology and origins of the gigantic, but poorly known, canyon systems that exist beyond the continental shelf. The spectacular Murray Canyons south of Kangaroo Island, with their complex and extensive channel systems and 2-km high cliffs, were a special focus of the investigation. The information collected and resulting research will assist implementation of Australia's Oceans Policy and Australia's Marine Science and Technology Plan, and in particular, the development of the South-east Regional Marine Plan by the National Oceans Office. The new data, integrated with the pre-existing seabed data sets, provide the basis for environmental management strategies and plans, and also provide framework information to support future biological and physical scientific field studies and research. AUSCAN was completed as two cruise legs totalling 3 weeks using the 120-m R/V Marion Dufresne of the French Polar Institute (IPEV). The survey used a range of geophysical, sampling and oceanographic equipment carried on the ship, but vital to the AUSCAN program were the ship's Thales Sea Falcon 11 multibeam sonar swath-mapper and its giant piston corer, `Calypso?. The multibeam system produces high-resolution bathymetric and backscatter images of the sea floor at 15 knots across a swath up to 20 km wide in deep water, while `Calypso' is capable of recovering deepsea sediment cores up to 60 m long. The cruise was based on excellent international scientific cooperation, and included scientists from Australia, France, Germany, other European countries, and the USA. IPEV was the main French organisation involved, while Australian institutions included Geoscience Australia (GA), the Australian National University, SARDI (South Australian Research & Development Institute) and the National Oceans Office (NOO). CSIRO Marine Research (Hobart) also provided input during the planning phase. NOO provided much of the Australian funding and support because of AUSCAN's direct and important relevance to current regional marine planning and environmental management initiatives, including development of National Bioregionalisation and the South-east Regional Marine Plan. GA managed the project for NOO. The AUSCAN program was designed to build on earlier major swath-mapping surveys involving French-Australian cooperation (GA and IPEV/IFREMER), such as TASMANTE off west Tasmania and on the South Tasman Rise, MARGAU off southwest Western Australia, and AUSTREA-1 off southeast and southern Australia. AUSCAN swath-mapped 70,000 km of seabed (about the size of Tasmania), filling many of the existing data gaps along the southern margin and now allowing detailed maps and images of almost the entire continental slope from Western Australia to Tasmania to be produced for the first time. AUSCAN also acquired 3.5 kHz sub-bottom profiler, gravity, magnetics and oceanographic data along 9,000 km of survey line.

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This report is one of a series of environmental summaries of frontier basins, which are scheduled for acreage release during the timeframe of the 'Energy Security Initiative' (2007-2011). The aim of these reports is to synthesise the available environmental information to adequately equip the exploration industry to anticipate as many as possible of the environment-related issues that may impact on exploration and potential future production activities. The environmental information for the Vlaming Sub-basin and Mentelle Basin has been compiled and presented in a manner consistent with the Geographic Information System (GIS) provided with this report. The GIS includes the results of an analysis to obtain representative seascapes. Seascapes are the principal environmental output and in recent years assisted Department of Environment, Water, Heritage and the Arts with the design and implementation of a National Representative System of Marine Protected Areas for Australia (Section 1.1). The following section summarises the geological history of the Vlaming Sub-basin and Mentelle Basin and provides a tectonic and depositional context for the geophysical data and geomorphology of the sub-basin, which are discussed in Sections 3 and 4, respectively. The surface sediment properties are described in Section 5. These sections provide all of the information necessary to characterise benthic habitats. Section 6 discusses the oceanographic processes operating in the sub-basin, which influence both the benthic and pelagic ecology described in Section 7. Section 8 synthesises the information contained in the first seven sections into a seascape map of the Vlaming Sub-basin and Mentelle Basin.

The magma-poor southern Australian rifted margin formed as a result of a long history of lithospheric extension that commenced in the Middle Jurassic. Breakup with Antarctica was diachronous, commencing in the west at ~83 Ma and concluding in the east at ~34 Ma. Initial NW-SE ultra-slow to slow seafloor spreading (83-45 Ma), followed by N-S fast spreading (45 Ma-present), resulted in a broad threefold segmentation of the margin: a long E-W oriented divergent margin segment (Bight-western Otway basins); a NW-SE trending transitional segment (central Otway-Sorell basins); and a N-S oriented transform margin (southern Sorell-South Tasman Rise). Segmentation appears to have been strongly controlled by the pre-existing basement structure. The divergent and western transitional margin segments are characterised by a broad region of lithospheric thinning and thick extensional basin development. In this region, a well-developed ocean-continent transition zone includes basement highs interpreted as exhumed sub-continental lithospheric mantle. Mapping of stratigraphic sequences provides insights into the processes that took place at the evolving margin, including the timing of mantle exhumation, and the diachronous nature of crustal thinning and breakup. The orientation and segmentation of the western and transitional margin segments suggests that initial spreading is likely to have been accommodated by short, extension-parallel transform segments. In the easternmost part of transitional zone, lithospheric thinning is not as marked and the continent-ocean boundary is interpreted to comprise both rift and long transform elements. Here, roughly N-S oriented extension resulted in the development of strongly transtensional basins.