In 2008-09, under the Offshore Energy Security Program, Geoscience Australia (GA) acquired 800 km of 2D seismic (Southwest Margin seismic survey) along with regional gravity and magnetic data (Southwest Margin Marine Reconnaissance survey) in the southern Carnarvon Basin. Data acquisition targeted the western Bernier Platform, as well as the adjoining poorly explored deepwater (>500m) parts of the margin, where prominent gravity lows indicated likely southern extension of the Exmouth Sub-basin and northern extension of the Houtman Sub-basin. The 2011 Acreage Release areas in the frontier part of the southern Carnarvon Basin are about the same size as the combined Rankin Platform, Barrow and Dampier Sub-basins. Only two wells (Pendock 1A and Herdsman 1) have been drilled in and in close proximity to these Acreage Release areas, providing only limited information on stratigraphy and petroleum systems of the region. The newly acquired seismic and potential field data were used to evaluate structure, stratigraphy and petroleum potential of the area. Analysis of the seismic data resulted in better understanding of tectonic and depositional history, including the role of extensive Early Cretaceous volcanism. Sufficient sediment thickness and a wide-range of possible structural and stratigraphic plays have been identified in the 2011 Acreage Release areas.

In March and April, 2012, Geoscience Australia undertook a seabed characterisation survey, aimed at supporting the assessment of CO2 storage potential of the Vlaming Sub-basin, Western Australia. The survey, undertaken as part of the National CO2 Infrastructure Plan program was targeted to provide an understanding of the link between the deep geological features of the area and the seabed, and connectivity between them as possible evidence for seal integrity. Data was acquired in two sections of the Rottnest Shelf lying above the regional seal - the South Perth Shale - and the underlying potentially CO2-suitable reservoir, the Gage Sandstone. Seabed samples were taken from 43 stations, and included 89 seabed grab samples. A total of 653 km2 of multibeam and backscatter data was obtained. Chirper shallow sub-bottom profile data was acquired concurrently. 6.65 km2 of side-scan sonar imagery was also obtained. The two surveyed areas, (Area 1 and Area 2), are set within a shallow sediment starved shelf setting. Area 2, situated to the southwest of Rottnest Island, is characterised by coralline red algal (rhodolith) beds, with ridges and mounds having significant rhodolith accumulations. The geomorphic expression of structural discontinuities outcropping at the seabed is evident by the presence of linear fault-like structures notable in Area 1, and north-south trending lineaments in Area 2. North-south trending structural lineaments on the outer section of Area 2 have in places, mounds standing 4-5 m above the seafloor in water depths of 80-85 m. Although there are apparent spatial correlations between seabed geomorphology and the structural geology of the basin, the precise relationship between ridges and mounds that are overlain by rhodolith accumulations, fluid seepage, and Vlaming Sub-basin geology is uncertain, and requires further work to elucidate any links.

Processed Stacked and Migrated SEG-Y seismic data and section images for the Georgina - Arunta Deep Crustal Seismic Survey. This survey was primarily funded through the Onshore Energy Security Program and was acquired in collaboration the Northern Territory Geological Survey. The objectives of the survey were to image the Georgina and Amadeus basins to enhance the knowledge of their petroleum prospectivity, and to investigate the uranium potential of the Arunta Inlier. Raw data for this survey are available on request from clientservices@ga.gov.au

The Bremer Sub-basin, which forms part of the Bight Basin off the southern coast of Western Australia, is a deep-water (100-4000 m water depth) frontier area for petroleum exploration. No wells have been drilled to test the sub-basin's petroleum potential, with company exploration limited to a regional seismic survey by Esso Australia Ltd in 1974. Early studies identified the Bremer Subbasin as a series of Middle Jurassic-Early Cretaceous half graben, which contain potentially prospective structures for trapping hydrocarbons. However, a lack of sub-surface geological data, along with the deep-water setting, discouraged exploration of this area for over 30 years. In 2003, the Bremer Sub-basin was identified as a key frontier area in Geoscience Australia's New Oil Program where new exploration opportunities might occur. Subsequently, Geoscience Australia's Bremer Sub-basin Study commenced in 2004 with an aim to determine if the sub-basin formed under suitable geological conditions to generate and trap large volumes of hydrocarbons.

The Bight Basin Sampling and Seepage Survey (SS01/2007), was undertaken in February-March 2007 as the final data acquisition activity of the Commonwealth Government's New Petroleum Program (2003-2007). The survey was designed to address two key petroleum systems issues in the Bight Basin. In order to assist in our understanding of the distribution of source rocks in the basin, the survey aimed to sample the distal facies of potential source intervals of Albian-Santonian age at locations on the seaward edges of the Ceduna and Eyre Terraces. Secondly, the survey aimed to investigate the presence of active petroleum systems by sampling and obtaining geophysical data at potential natural hydrocarbon seepage sites across the Ceduna Sub-basin. Nine areas of interest were identified for surveying in the eastern Bight Basin, including areas where the targeted Albian-Santonian section outcrops on the seafloor, and areas where there was seismic and other geophysical and remotely sensed evidence of possible hydrocarbon seepage. The survey, took place from 24 February-17 March 2007 using the Marine National Facility vessel R/V Southern Surveyor. The survey successfully sampled all nine targeted areas and collected 37 dredge hauls, 69 gravity cores and 15 grab samples, as well as 4600 km of swath data, and 2400 km of sub-bottom profile data. The Bight Basin Sampling and Seepage Survey was very successful in addressing the most critical of its objectives, recovering samples from the exposed up-dip northwestern edge of the Ceduna Sub-basin that provide the first evidence for a world-class marine Cretaceous source rock in the Bight Basin.

The Jurassic-Cretaceous Bight Basin is situated along the western and central parts of the southern Australian continental margin. The largely offshore basin extends from the southern tip of Western Australia in the west, to just south of Kangaroo Island in the east, where it adjoins the Otway Basin. The thickest depocentre in the basin is the Ceduna Sub-basin, which contains a sedimentary section in excess of 15 km thick. The deepwater Recherche Sub-basin adjoins the Ceduna Sub-basin and extends west along the southern margin as far as the Leeuwin Fracture Zone. Perched half-graben systems of the Denmark, Bremer and Eyre sub-basins lie to the north of the Recherche Sub-basin. The Duntroon Sub-basin adjoins the Ceduna Sub-basin to the east, and consists of a series of oblique extensional depocentres. The Bight Basin evolved through repeated episodes of extension and thermal subsidence leading up to, and following, the commencement of sea-floor spreading between Australia and Antarctica. The basin was initiated during a period of Middle-Late Jurassic to Early Cretaceous upper crustal extension. A northwest-southeast to north-south extension direction, superimposed on east-west and northwest-southeast-oriented basement structures, resulted in oblique to strongly oblique extension and the formation of en echelon half graben in the Denmark, Bremer, Eyre, inner Recherche, eastern Ceduna and Duntroon sub-basins. The areal extent of the early extensional structures beneath the thick Ceduna Sub-basin cannot be determined at present. The anomalously thick nature of the Ceduna Sub-basin may indicate, however, that Jurassic-Early Cretaceous rifts are present at depth. Post-rift thermal subsidence was followed by a phase of accelerated subsidence, which commenced in the Late Albian and continued until continental break-up in the Late Santonian-Early Campanian. During this phase of enhanced subsidence, the dominant structural feature was a system of gravity-driven, detached extensional and contractional structures, which developed in the Ceduna Sub-basin during the Cenomanian as a result of deltaic progradation. Evidence for upper crustal extension during this basin phase is limited to Turonian-Santonian extensional faulting, and the reactivation and propagation of Cenomanian growth faults. The commencement of sea-floor spreading at ~83 Ma was followed by a further period of thermal subsidence and establishment of a passive margin

The Australian Southern Margin SEEBASE® Compilation represents many years of work by SRK in southern Australia in the petroleum, mineral and coal sectors. During this time SRK has undertaken numerous projects in southern Australia with both the private and government sectors. These projects have resulted in the development of a model of the geological evolution of southern Australia from Archean to Recent that is summarised in this GIS and report. The model is consistent with a wide range of datasets including airborne and satellite remote sensing, seismic, well and outcrop observations. The basins of Australia's Southern margin formed by the repeated reactivation of long-lived basement structures. By understanding the genesis and geometry of the old basement structures, we have produced a model for the evolution of the Southern Margin basins that explains their structural framework and architecture. This SEEBASE model and structural interpretation can now be used as the basis for a new understanding of the sequence stratigraphy and petroleum systems of the margin.

The Early Permian to Middle Triassic Bowen and Gunnedah basins in eastern Australia developed in response to a series of interplate and intraplate tectonic events located to the east of the basin system. The initial event was extensional and stretched the continental crust to form part of the major Early Permian East Australian Rift System that stretched at least from far north Queensland to southern New South Wales. The most commercially important of the rift-related features are a series of half graben that form the Denison Trough, now the site of several producing gas fields. The eastern part of the rift system commenced at about 305 Ma and was volcanic dominated. In contrast, the half graben in, and to the west of, the Bowen Basin were non-volcanic, and appear to have initiated at about 285 Ma. These half graben are essentially north-south in length with an extension direction of approximately east-northeast. Mechanical extension appears to have ceased at about 280 Ma, when subsidence became driven by thermal relaxation. The extension occurred in a backarc setting, in response to far field stresses that propagated from the west-dipping subduction system at the convergent plate margin of East Gondwana that was located to the east of the East Australian Rift System.

The Onshore Energy Security Program, funded by the Australian Government, Geoscience Australia has acquired deep seismic reflection data across several frontier sedimentary basins to stimulate interest in petroleum exploration in onshore Australia. Detailed interpretation of deep seismic reflection profiles from four onshore basins, focusing on overall basin geometry and internal sequence stratigraphy will be presented here, with the aim of assessing the petroleum potential of the basins. At the Southern end of the exposed part of the Mt Isa Province, northwest Queensland, a deep seismic line (06GA-M6) crosses the Burke River Structural Zone of the Georgina Basin. The basin here is >50 km wide, with a half graben geometry, and bound in the west by a rift border fault. The Millungera Basin in northwest Queensland is completely covered by the thin Eromanga basin and was unknown prior to being detected on two seismic lines (06GA-M4 and 06GA-M5) acquired in 2006. Following this, seismic line 07GA-IG1 imaged a 65 km wide section of the basin. The geometry of internal stratigraphic sequences and post-depositional thrust margin indicate that the original succession was much thicker than preserved today. The Yathong Trough in the southeast part of the Darling Basin in NSW has been imaged in seismic line 08GA-RS2 and interpreted in detail using sequence stratigraphic principles, with several sequences being mapped. The upper part of this basin contains Devonian sediments, with potential source rocks at depth.

The Bight Basin contains a thick, prospective Jurassic-Cretaceous sedimentary section. Recent work by both Geoscience Australia and the petroleum exploration industry has increased our understanding of the structural and stratigraphic development, and the range of opportunities available in this frontier basin. The presence of thick deltaic units and indications of active petroleum systems further enhance its prospectivity. Although the basin is being tested by new drilling it remains one of the least explored passive margins in the world, and will require much more exploration to fully assess its potential.