High-precision radiometric dating using Chemical Abrasion-Isotope Dilution Thermal Ionisation Mass Spectrometry (CA-IDTIMS) has allowed the recalibration of the numerical ages of Permian and Triassic spore-pollen palynozones in Australia. These changes have been significant, with some zonal boundaries in the Permian shifting by as much as six million years, and some in the Triassic by more than twice that. Most of the samples analysed came from eastern Australian coal basins (Sydney, Gunnedah, Bowen, Galilee) where abundant volcanic ash beds occur within the coal-bearing successions. The recalibrations of these widely used palynozones have implications for the dating of geological events outside the basins from where samples were obtained. Our revised dates for the Permian palynozones can now be applied to all Permian basins across Australia, including the Perth, Carnarvon, Canning and Bonaparte basins (along the western and northern continental margins), the Cooper and Galilee basins (in central Australia), and the Bowen, Gunnedah and Sydney basins (in eastern Australia). Revised regional stratigraphic frameworks are presented here for some of these basins. The impact of an improved calibration of biostratigraphic zones to the numerical timescale is broad and far-reaching. For example, the more accurate stratigraphic ages are the more closely burial history modelling will reflect the basin history, thereby providing control on the timing of kerogen maturation, and hydrocarbon expulsion and migration. These improvements can in turn be expected to translate in to improved exploration outcomes. We have initially focused on the Permian and provide preliminary results for the Triassic, but intend to expand recalibrations to include Jurassic, Cretaceous and Paleozoic successions beyond the Permian. Preliminary data indicates that significant changes to these calibrations are also likely.

<p>The Roebuck Basin and adjoining Beagle Sub-basin are underexplored areas on Australia’s North West Shelf and are undergoing renewed exploration interest since the discovery of oil at Phoenix South 1 and gas at Roc 1, 2 in the Bedout Sub-basin. A well folio of 24 offshore wells across the Beagle, Bedout, Rowley and Barcoo sub-basins was completed as part of Geoscience Australia’s assessment of hydrocarbon prospectivity across the region. The study consists of composite well log plots summarising lithology, stratigraphy, GA’s newly acquired biostratigraphic and geochemical data and petrophysical analysis, in conjunction with revised sequence interpretations. <p>The wells included in the well folio package are: <p>Anhalt 1, Barcoo 1 ST2, Bedout 1, Bruce 1, Cossigny 1, De Grey 1A ST1, Delambre 1, Depuch 1, East Mermaid 1B ST1, Hanover South 1, Huntsman 1, Keraudren 1. Lagrange 1, Minilya 1, Nebo 1, Omar 1, Phoenix 1, Phoenix 2, Phoenix South 1 ST1 ST2, Picard 1, Poissonnier 1, Roc 1, Steel Dragon 1 and Wigmore 1

This OGC conformant web service delivers data from Geoscience Australia's Reservoir, Facies and Hydrocarbon Shows (RESFACS) Database. RESFACS is an interpretative reservoir/facies database containing depth-based information regarding permeability, porosity, shows, depositional environment and biostratigraphy of petroleum wells.

This OGC conformant web service delivers data from Geoscience Australia's Reservoir, Facies and Hydrocarbon Shows (RESFACS) Database. RESFACS is an interpretative reservoir/facies database containing depth-based information regarding permeability, porosity, shows, depositional environment and biostratigraphy of petroleum wells.

The Triassic is an important interval for Australian petroleum exploration, with Middle to Upper Triassic Mungaroo Formation reservoirs in the Northern Carnarvon Basin, and recent Lower Triassic discoveries in the Roebuck Basin. The chronostratigraphic understanding of Triassic petroleum systems is underpinned by biostratigraphic dating using palynological zonations. The numerical ages of these zones are usually assigned through inference and interpolation, often via tenuous correlations to the international geologic timescale using scattered marine biota, (primarily foraminifera, and rare ammonites, conodonts and/or dinoflagellates). In contrast, we tie Australian biozones to the timescale through Chemical Abrasion-Isotope Dilution Thermal Ionisation Mass Spectrometry (CA-IDTIMS) dating of interbedded volcanic tuffs. Such ashfalls are reasonably common in Australian basins, and can provide high-precision CA-IDTIMS ages if they contain magmatic zircons. We recently recalibrated Australian middle and late Permian palynozones using this approach and preliminary results suggest that Triassic biozone ages are likewise in need of considerable revision We have targeted Triassic tuffs across Queensland, (Tarong beds, Brisbane Tuff, Moolayember Formation, Rewan Group), New South Wales (Garie Formation, Coal Cliff Sandstone, Milligan Road Formation), and Tasmania (upper Triassic coal measures) to provide numerical ages for palynozones. Additional dates in New Zealand (Murihiku Supergroup) and Timor-Leste (Wailuli Formation) will allow international correlation of dinocyst and spore-pollen zones. Numerical constraints for Triassic biozone boundaries facilitate correlation of Australian biozones with the international geologic timescale. This can impact burial history models used in petroleum exploration anywhere these biozones are used, often far beyond the basins from which the samples were collected.

Geoscience Australia is leading a regional evaluation of potential mineral, energy and groundwater resources through the Exploring for the Future (EFTF) program. This stratigraphic assessment is part of the Onshore Basin Inventories project, and was undertaken to understand Devonian-aged depositional systems and stratigraphy in Queensland’s Adavale Basin. Such data are fundamental for any exploration activities. Maximising the use of existing well data can lead to valuable insights into the regional prospectivity of sedimentary basins. Data from 53 Adavale Basin wells have been used to evaluate subsurface stratigraphy, depositional environments and hydrocarbon shows across the basin. Stratigraphic data from 26 representative wells, where the well intersected at least three Devonian stratigraphic units, are used to generate chronostratigraphic time-space charts and two-dimensional well correlations within, and between, different (northern, north central, central, west central, east central and southern) parts of the basin. The primary objectives of the study are: • stratigraphic gap analysis to identify geological uncertainties and data deficiencies in the areas of interest, • integrate the well data with Geoscience Australia’s databases (i.e., Australian Stratigraphic Units, Time Scale, Geochronology, STRATDAT, RESFACS),the Geological Survey of Queensland’s Datasets and publicly available (published and unpublished) research data and information, • determine the lithostratigraphic unit tops, log and lithology characterisations, depositional facies, boundary criteria, spatial and temporal distribution and regional correlations, • integrate key biostratigraphic zones and markers with geochronological absolute age dates to generate a chronostratigraphic Time-Space Diagram of the basin. This work improves the understanding of the chronostratigraphic relationships across the Adavale Basin. The age of the sedimentary successions of the basin have been refined using geochronology, biostratigraphy and lithostratigraphic correlation. The chronostratigraphic and biozonation chart of the Adavale Basin has been updated and the stratigraphic, biostratigraphic and hydrocarbon shows datasets will be available for viewing and download via the Geoscience Australia Portal (https://portal.ga.gov.au/restore/15808dee-efcd-428e-ba5b-59b0106a83e3).

Geoscience Australia’s biostratigraphic database (STRADAT) provides information about the biozonation of sedimentary rocks that were intersected by offshore petroleum wells. The basic unit of biostratigraphy is the biozone, a geological unit formally defined on the basis of the fossil groups contained within. Widely used taxa include trilobites, brachiopods, conodonts, dinoflagellate cysts, foraminifera, graptolites, spores and pollen, as well as nanofossils. Such units are typically defined by either the first appearance (range base) and apparent extinctions (range top/last appearance), or abundance of fossil index species. These fossil indices should ideally be relatively abundant, short-lived taxa that are easy to recognise and as geographically widespread as possible. Zonal schemes based on several different fossil groups can be used in parallel, and the zones can be calibrated to the absolute geological timescale (i.e., Geologic Time Scale 2004, 2012, 2020). Biozones allow the identification of spacial—temporal relationships and the distribution of lithostratigraphic units within and across sedimentary basins. They facilitate the understanding of subsurface geology and identification of source, reservoir and seal rocks, key elements of petroleum systems. These biostratigraphic data originate from well completion reports and destructive analyses reports that are submitted by the petroleum industry under the Offshore Petroleum and Greenhouse Gas Storage Act (OPGGSA) 2006 and previous Petroleum (submerged Lands) Act (PSLA) 1967. These data are also sourced from biostratigraphic studies by Geoscience Australia and its predecessor organisations, the Australian Geological Survey Organisation (AGSO) and the Bureau of Mineral Resources (BMR), as well as from state and territory geological organisations. Other open file data from publications, including university theses, are also captured. The database structure has evolved over time and will keep changing as different types of geological timescales data become available and the delivery platform changes. Data was initially delivered through the Petroleum Wells web page, http://dbforms.ga.gov.au/www/npm.well.search, which is in the process of being decommissioned. The biostratigraphic data will be available for viewing and download via the Geoscience Australia Portal Core, https://portal.ga.gov.au/.

Australia has some of the best documented Permian basins in Gondwana, but much of the succession is nonmarine. Calibration of the local palynostratigraphic scheme (Price, 1997) to the global timescale was indirect and very difficult, having traditionally relied on correlations from relatively sparse, high-latitude, marine strata, within which ammonoids and conodonts are rare, fusulinids are unknown, and much of the other fauna (brachiopods, bivalves) is endemic. Tie points are rare and often tenuous (Mantle et al., 2010): one example is the record of a single specimen of the ammonoid Cyclolobus persulcatus from the Cherrabun Member of the Hardman Formation, in the Canning Basin, Western Australia (Foster and Archbold, 2001), dated as ¿post-Guadalupian¿ by Glenister et al. (1990) and ¿Capitanian¿Dzhulfian¿ by Leonova (1998). In eastern Australia, the Permian succession is replete with felsic ash beds, many of which contain zircons. Ash beds are rare in Western Australia, but some have been found in the Canning Basin. Sampling of ash beds has been coupled with sampling of adjacent clastics for palynomorphs, mostly from drillcore and coalmines in the Sydney, Gunnedah, Bowen and Galilee basins in eastern Australia, and drillcore in the Canning Basin in Western Australia. The zircons have been subjected to the Chemical Abrasion-Isotope Dilution Thermal Ionisation Mass Spectrometry (CA-IDTIMS) technique for U-Pb dating (Mattinson, 2005). The resultant radioisotopic dates, with associated palynostratigraphic determinations, permit the direct calibration of the Price (1997) scheme to the numerical timescale. Some of the data has been cited previously (Smith & Mantle, 2013; Nicoll et al., 2015, 2016; Metcalfe et al., 2015; Phillips et al., 2016). A more detailed synthesis of the Guadalupian and Lopingian will be published soon (Laurie et al., in press) and a study of the Cisuralian is in progress. The results of Laurie et al. (in press) indicate that the palynozones in the Guadalupian and Lopingian of Australia are significantly younger than currently calibrated (Figure 1). The recalibrations indicate: 1. the top of the Praecolpatites sinuosus (APP3.2) Zone lies in the early Roadian; 2. the top of the Microbaculispora villosa (APP3.3) Zone lies in the middle Roadian; 3. the top of the Dulhuntyispora granulata (APP4.1) Zone lies in the Wordian; 4. the top of the Didecitriletes ericianus (APP4.2) Zone lies in the first half of the Wuchiapingian; 5. the entire Dulhuntyispora dulhuntyi (APP4.3) Zone lies within the Wuchiapingian; and 6. the top of the Dulhuntyispora parvithola (APP5) Zone lies at or near the Permian¿Triassic boundary. These new calibrations involve some major changes, the most significant being the base of the Dulhuntyispora parvithola (APP5) Zone, which is about 6 million years younger than previously calibrated. A preliminary assessment of the Cisuralian, in eastern Australia, suggests that the Pseudoreticulatispora pseudoreticulata (APP2.1) Zone and the Microbaculispora trisina (APP2.2) Zone (APP2.2) are both of greater duration than previously thought. Contrastingly, the Pseudoreticulatispora confluens (APP1.2.2) Zone is older and of shorter duration than previously suggested (Mantle et al., 2010). However, at this stage this interpretation is based on relatively few dated ash beds (Figure 1). Preliminary data indicates that similar miscorrelations are also a feature of the current Mesozoic palynomorph zonation, and future work will attempt to remedy this.