Extended abstract to accompany oral conference presentation. Full version of the short abstract (GEOCAT 70799).

Geodynamic modelling of selected aspects of the Bowen, Gunnedah, Surat and Eromanga basins constrains the mechanisms that were operating during their formation. For the Bowen and Gunnedah basins, a quantitative analysis of the early Late Permian to Middle Triassic foreland loading phase examined the relative roles of static loading versus dynamic loading associated with the convergent plate margin. Subsidence in the initial foreland phase in the early Late Permian is consistent with platform tilting due to corner flow in the mantle associated with west-directed subduction. Later in the Late Permian, platform tilting probably continued to be the dominant cause of subsidence, but increasing amounts of subsidence due to foreland loading occurred as the thrust front in the New England Orogen migrated westward. In the latest Permian and Early Triassic, static flexural loading due to foreland loads is dominant and may be the sole cause for basin subsidence. For the Surat and Eromanga basins, the tectonic subsidence across an east-west transect is modelled to assess the contribution of dynamically-induced platform tilting, due to viscous mantle corner flow, in basin subsidence. The modelling suggests that subsidence was again controlled by dynamic platform tilting, which provides a mechanism for both the nearfield and farfield effects. Uplift of the Eastern Highlands in the mid-Cretaceous may also be related to viscous corner flow driven by west-directed subduction beneath eastern Australia, with the uplift being due to rebound of the lithosphere after the cessation of subduction.

New 2D seismic data acquired in the Mentelle Basin by Geoscience Australia in 2008-09 has been used for a seismic facies study of the post-rift succession. The Mentelle Basin is a large deep to ultra deep-water, frontier basin located on Australia's southwestern margin about 200 km southwest of Perth. The study focused on the post-rift sequences deposited following the breakup between Australia and Greater India. Stratigraphic wells DSDP 258 and DSDP 264 provide age and lithological constraints on the upper portion of the post-rift succession down to mid-Albian strata. The depositional environment and lithology of the older sequences are based on analysis of the seismic facies, stratal geometries and comparisons to the age equivalent units in the south Perth Basin. Fourteen seismic facies were identified based on reflection continuity, amplitude and frequency, internal reflection configuration and external geometries. They range from high continuity, high amplitude, parallel sheet facies to low continuity, low amplitude, parallel, subparallel and chaotic sheet, wedge and basin-fill facies. Channel and channel-fill features are common in several facies as well as a mounded facies (probably contourite) and its associated ponded turbidite fill. A progradational sigmoidal to oblique wedge facies occurs at several stratigraphic levels in the section. A chaotic mound facies, probably comprising debrite deposits, has a localised distribution. Seismic facies analysis of the post-rift sequences in the Mentelle Basin has contributed to a better understanding of the depositional history and sedimentation processes in the region, as well as provided additional constraints on regional and local tectonic events.

The seismic stacking velocity data in the Great Australian Bight are a useful dataset for calculating depths and sediment thicknesses. This work presents time-depth relationships computed from an unfiltered stacking velocity database and compares these with depths from sonobuoy P-wave velocities and exploration well sonic logs. The comparison suggests that a total sediment thickness over-estimate for the Ceduna Sub-basin of about 15% can be expected from the depths derived from stacking velocities. On the other hand, for sediment thickness calculations down to ~4 s two-way travel time below sea floor, stacking velocity data give comparable depths to those obtained from the wells' sonic logs. A piece-wise formula is offered which scales the time-depth function for the Ceduna Sub-basin in order to compensate for the depth overestimate inherent in using stacking velocities to calculate total sediment thickness. Megasequence boundary depths are calculated for the Ceduna Terrace to further illustrate data quality.

No abstract available

Identification of major hydrocarbon provinces from existing world assessments for hydrocarbon potential can be used to identify those sedimentary basins at a global level that will be highly prospective for CO2 storage. Most sedimentary basins which are minor petroleum provinces and many non-petroliferous sedimentary basins will also be prospective for CO2 storage. Accurate storage potential estimates will require that each basin be assessed individually, but many of the prospective basins may have ranges from high to low prospectivity. The degree to which geological storage of CO2 will be implemented in the future will depend on the geographical and technical relationships between emission sites and storage locations, and the economic drivers that affect the implementation for each source to sink match. CO2 storage potential is a naturally occurring resource, and like any other natural resource there will be a need to provide regional access to the better sites if the full potential of the technology is to be realized. Whilst some regions of the world have a paucity of opportunities in their immediate geographic confines, others are well endowed. Some areas whilst having good storage potential in their local region may be challenged by the enormous volume of CO2 emissions that are locally generated. Hubs which centralize the collection and transport of CO2 in a region could encourage the building of longer and larger pipelines to larger and technically more viable storage sites and so reduce costs due to economies of scale.

The rifted margins of eastern and southern Australia formed during multiple periods of extension associated with the fragmentation and dispersal of Gondwana in the Late Jurassic to Early Eocene (Veevers & Ettreim 1988; Veevers et al. 1991). The sedimentary basins of the Southern Rift System (Stagg et al. 1990) extend from Broken Ridge in the west, to the South Tasman Rise (STR) in the east. Collectively, these depocentres cover an area in excess of 1 million square kilometres (excluding the STR), with the thickest sediments (up to 15 km) occurring in the Ceduna Sub-basin of the Bight Basin. Early phases of the extension during the late Middle Jurassic to Early Cretaceous resulted in the formation of a series of west-northwesterly trending continental rift basins along the southern margin of Australia and a series of north-northwest trending transtensional basins along the western margin of Tasmania. The amount of upper crustal extension varied between basins of the rift system. This phase of upper crustal extension preceded eventual breakup between the Australian and Antarctic plates off the Bight Basin in the latest Santonian to earliest Campanian (Sayers et al. 2001). The nature of source rocks within the rift basins reflects the eastward propagation of the rift system through time, with largely terrestrial systems dominating in the early rift stages, followed by marine inundation from the Aptian onwards (west of the Otway Basin). In the Otway Basin, the first marine influence is recorded during the early Turonian, while in the Sorell and Bass basins marine conditions prevailed from ?Maastrichtian and middle Eocene time, respectively. Terrestrial progradational systems in the Late Cretaceous are important in the maturation of potential source rocks in the Bight and Otway basins, while Neogene carbonate-dominated systems are important in the Sorell, Bass and Gippsland basins. Outside of the Gippsland Basin where exploration has reached a mature status, the southern margin basins remain frontier to moderately exploration areas, with an overall drilling density (excluding the Gippsland Basin) of approximately 1 well per 6,000 square kilometres. Key Words: Australian Southern Margin, Southern Rift System, petroleum systems References SAYERS, J., SYMONDS, P.A., DIREEN, N.G. and BERNARDEL, G., 2001. Nature of the continent-ocean transition on the non-volcanic rifted margin of the central Great Australian Bight. In, Wilson, R.C.L., Whitmarsh, R.B., Taylor, B., and Froitzheim, N., (Eds), Non-Volcanic Rifting of Continental Margins; A Comparison of Evidence from Land and Sea. Geological Society, London, Special Publications, 187, 51?77. STAGG, H.M.J., COCKSHELL, C.D., WILLCOX, J.B., HILL, A., NEEDHAM, D.J.L., THOMAS, B., O?BRIEN, G.W. and HOUGH, P., 1990. Basins of the Great Australian Bight region, geology and petroleum potential. Bureau of Mineral Resources, Australia, Continental Margins Program Folio 5. VEEVERS, J.J. and ETTREIM, S.L., 1988. Reconstruction of Australia and Antarctica at breakup (95 ? 5 Ma) from magnetic and seismic data at the continental margin. Australian Journal of Earth Sciences, 35, 355?362. VEEVERS, J.J., POWELL, C.MCA. and ROOTS, S.R., 1991. Review of seafloor spreading around Australia, I. Synthesis of the patterns of spreading. Australian Journal of Earth Sciences, 38, 373?389. WILLCOX, J.B. and STAGG, H.M.J., 1990. Australia?s southern margin, a product of oblique extension. Tectonophysics, 173, 269?281.

Measurements of water turbidity, currents, seafloor sediment samples and geophysical data document the sedimentary processes and the Late Quaternary sedimentary history of a continental shelf valley system on the East Antarctic continental margin.

Promotional flyer describing the GA programme in national unconventional hydrocarbon prospectivity and resource assessment commenced in 2011 by the Onshore (Unconventional) Hydrocarbons Section, Basin Resources Group, Energy Division.

The seismic stacking velocity data in the Great Australian Bight are a useful dataset for calculating depths and sediment thicknesses. This work compares these data with P-wave velocities from sonobuoys and sonic logs from wells, and on this basis a depth over-estimate of at least 15% can be expected from the depths derived from stacking velocities. Megasequence boundary depths are calculated for the Ceduna Terrace to further illustrate data quality. The database makes avaliable the unfiltered stacking velocities using conventional and horizon-consistent formats.