Stratigraphy (incl. biostratigraphy
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<div>Gas production from the Inner Otway Basin commenced in the early 2000s but the deep-water part of this basin remains an exploration frontier. Ground-truthing of depositional environments (DE) and gross depositional environments (GDE) is an important contribution to play-based exploration in the Otway Basin. This digital dataset consists of core logs and core photographs of approximately 700 m of core from 19 wells across the entire offshore basin. Observations recorded in the logs include lithology, modal grain size, stacking patterns, carbonate mud percentage, bioturbation index, and DE/GDE intervals. Cubitt et al. 2023 describes how core-based DE/GDE interpretations were applied to wireline log signatures with interpretations made from TD to the base Cenozoic in 38 wells across the basin. DE and DE tracks are included in the well composite logs compiled by Nguyen et al (2024).</div>
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<div>The Lake Eyre surface water catchment covers around 1,200,000 km2 of central Australia, about one-sixth of the entire continent. It is one of the largest endorheic river basins in the world and contains iconic arid streams such as the Diamantina, Finke and Georgina rivers, and Cooper Creek. The Lake Eyre region supports diverse native fauna and flora, including nationally significant groundwater-dependent ecosystems such as springs and wetlands which are important cultural sites for Aboriginal Australians.</div><div><br></div><div>Much of the Lake Eyre catchment is underlain by the geological Lake Eyre Basin (LEB). The LEB includes major sedimentary depocentres such as the Tirari and Callabonna sub-basins which have been active sites of deposition throughout the Cenozoic. The stratigraphy of the LEB is dominated by the Eyre, Namba and Etadunna formations, as well as overlying Pliocene to Quaternary sediments.</div><div><br></div><div>The National Groundwater Systems Project, part of Geoscience Australia's Exploring for the Future Program (https://www.eftf.ga.gov.au/), is transforming our understanding of the nation's major aquifer systems. With an initial focus on the Lake Eyre Basin, we have applied an integrated geoscience systems approach to model the basin's regional stratigraphy and geological architecture. This analysis has significantly improved understanding of the extent and thickness of the main stratigraphic units, leading to new insights into the conceptualisation of aquifer systems in the LEB.</div><div><br></div><div>Developing the new understanding of the LEB involved compilation and standardisation of data acquired from thousands of petroleum, minerals and groundwater bores. This enabled consistent stratigraphic analysis of the major geological surfaces across all state and territory boundaries. In places, the new borehole dataset was integrated with biostratigraphic and petrophysical data, as well as airborne electromagnetic (AEM) data acquired through AusAEM (https://www.eftf.ga.gov.au/ausaem). The analysis and integration of diverse geoscience datasets helped to better constrain the key stratigraphic horizons and improved our overall confidence in the geological interpretations.</div><div><br></div><div>The new geological modelling of the LEB has highlighted the diverse sedimentary history of the basin and provided insights into the influence of geological structures on modern groundwater flow systems. Our work has refined the margins of the key depocentres of the Callabonna and Tirari sub-basins, and shown that their sediment sequences are up to 400 m thick. We have also revised maximum thickness estimates for the main units of the Eyre Formation (185 m), Namba Formation (265 m) and Etadunna Formation (180 m).</div><div><br></div><div>The geometry, distribution and thickness of sediments in the LEB is influenced by geological structures. Many structural features at or near surface are related to deeper structures that can be traced into the underlying Eromanga and Cooper basins. The occurrence of neotectonic features, coupled with insights from geomorphological studies, implies that structural deformation continues to influence the evolution of the basin. Structures also affect the hydrogeology of the LEB, particularly by compartmentalising groundwater flow systems in some areas. For example, the shallow groundwater system of the Cooper Creek floodplain is likely segregated from groundwater in the nearby Callabonna Sub-basin due to structural highs in the underlying Eromanga Basin.</div><div> Abstract submitted and presented at the 2023 Australian Earth Science Convention (AESC), Perth WA (https://2023.aegc.com.au/)
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<div>In response to the acquisition of national-scale airborne electromagnetic surveys and the development of a national depth estimates database, a new workflow has been established to interpret airborne electromagnetic conductivity sections. This workflow allows for high quantities of high quality interpretation-specific metadata to be attributed to each interpretation line or point. The conductivity sections are interpreted in 2D space, and are registered in 3D space using code developed at Geoscience Australia. This code also verifies stratigraphic unit information against the national Australian Stratigraphic Units Database, and extracts interpretation geometry and geological data, such as depth estimates compiled in the Estimates of Geological and Geophysical Surfaces database. Interpretations made using this workflow are spatially consistent and contain large amounts of useful stratigraphic unit information. These interpretations are made freely-accessible as 1) text files and 3D objects through an electronic catalogue, 2) as point data through a point database accessible via a data portal, and 3) available for 3D visualisation and interrogation through a 3D data portal. These precompetitive data support the construction of national 3D geological architecture models, including cover and basement surface models, and resource prospectivity models. These models are in turn used to inform academia, industry and governments on decision-making, land use, environmental management, hazard mapping, and resource exploration.</div>
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<div>The interpretation of AusAEM airborne electromagnetic (AEM) survey conductivity sections in the Canning Basin region delineates the geo-electrical features that correspond to major chronostratigraphic boundaries, and captures detailed stratigraphic information associated with these boundaries. This interpretation forms part of an assessment of the underground hydrogen storage potential of salt features in the Canning Basin region based on integration and interpretation of AEM and other geological and geophysical datasets. A main aim of this work was to interpret the AEM to develop a regional understanding of the near-surface stratigraphy and structural geology. This regional geological framework was complimented by the identification and assessment of possible near-surface salt-related structures, as underground salt bodies have been identified as potential underground hydrogen storage sites. This study interpreted over 20,000 line kilometres of 20 km nominally line-spaced AusAEM conductivity sections, covering an area approximately 450,000 km2 to a depth of approximately 500 m in northwest Western Australia. These conductivity sections were integrated and interpreted with other geological and geophysical datasets, such as boreholes, potential fields, surface and basement geology maps, and seismic interpretations. This interpretation produced approximately 110,000 depth estimate points or 4,000 3D line segments, each attributed with high-quality geometric, stratigraphic, and ancillary data. The depth estimate points are formatted for Geoscience Australia’s Estimates of Geological and Geophysical Surfaces database, the national repository for formatted depth estimate points. Despite these interpretations being collected to support exploration of salt features for hydrogen storage, they are also intended for use in a wide range of other disciplines, such as mineral, energy and groundwater resource exploration, environmental management, subsurface mapping, tectonic evolution studies, and cover thickness, prospectivity, and economic modelling. Therefore, these interpretations will benefit government, industry and academia interested in the geology of the Canning Basin region.</div>
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<div>A prerequisite to understanding the evolution and resource potential of a basin is to establish a reliable stratigraphic framework that enables the correlation of rock units across multiple depocentres. Establishing a stratigraphic model for the Adavale Basin is challenging due to its structurally complexity, lack of well penetration and its lateral changes in facies. Biostratigraphy appears broad-scale, and despite providing chronostratigraphic control for the Lower Devonian Gumbardo Formation when combined with U/Pb zircon geochronology, the rest of the Devonian succession is hampered by a lack of microfossil assemblages and their poor preservation. The aim of this study is to establish an independent chemostratigraphic correlation across the Adavale Basin using whole rock inorganic geochemistry. Within this study, a total of 1489 cuttings samples from 10 study wells were analysed by Inductively Coupled Plasma – Optical Emission Spectrometry and Inductively Coupled Plasma – Mass Spectrometry for whole rock geochemistry, in order to establish an independent chemostratigraphic zonation scheme. Based on key elemental ratios selected to reflect changes in feldspars, clay minerals and provenance, the Devonian-aged stratigraphy is characterised into four chemostratigraphic mega-sequences that encompass the Gumbardo Formation (Mega-sequence 1); the Eastwood Formation, the Log Creek Formation and the Lissoy Sandstone (Mega-sequence 2); the Bury Limestone and the Boree Salt formations (Mega-sequence 3); and the Etonvale and the Buckabie formations (Mega-sequence 4). These mega-sequences have been further subdivided into a series of chemostratigraphic sequences that can be correlated across the study wells, establishing a regional correlation framework. </div> This Paper was submitted/presented to the 2023 Australian Petroleum Production & Exploration Association (APPEA) Conference 15-18 May, (https://www.appea.com.au/appea-event/appea-conference-and-exhibition-2023/). <b>Journal Citation:</b> Riley David, Pearce Tim, Davidson Morven, Sirantoine Eva, Lewis Chris, Wainman Carmine (2023) Application of elemental chemostratigraphy to refine the stratigraphy of the Adavale Basin, Queensland. <i>The APPEA Journal</i><b> 63</b>, 207-219. https://doi.org/10.1071/AJ22108
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<div>The Australian Government's Trusted Environmental and Geological Information (TEGI) program is a collaboration between Geoscience Australia and the CSIRO that aims to provide access to baseline geological and environmental data and information for strategically important geological basins. The initial geological focus is on the north Bowen, Galilee, Cooper, Adavale, and their overlying basins. This paper presents seven stratigraphic frameworks from these basin regions that underpin groundwater, environmental and resource assessments, identify intervals of resource potential, and can assist in management of associated risks to groundwater resources and other environmental assets. The construction of stratigraphic frameworks for this program builds upon existing lithostratigraphic schemes to capture the current state of knowledge. The frameworks incorporate play divisions for resource and hydrogeological assessments. A total of 33 play intervals are defined for the north Bowen, Galilee, Cooper, Adavale, and their overlying basins, using chronostratigraphic principles. Where possible, unconformities and flooding surfaces are used to define the lower and upper limits of plays. Data availability and temporal resolution are considered in capturing significant changes in gross depositional environments. The results from this work enable the consistent assessment of shared play intervals between basins, and also highlight uncertainties in the age and correlation of lithostratigraphic units, notably in the Galilee and north Bowen Basins.</div> This presentation was given at the 2023 Australasian Exploration Geoscience Conference (AEGC) 13-18 March, Brisbane (https://2023.aegc.com.au/)
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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).
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<div>This dataset presents results of a first iteration of a 3D geological model across the Georgina Basin, Beetaloo Sub-basin of the greater McArthur Basin and South Nicholson Basin (Figure 1), completed as part of Geoscience Australia’s Exploring for the Future Program National Groundwater Systems (NGS) Project. These basins are located in a poorly exposed area between the prospective Mt Isa Province in western Queensland, the Warramunga Province in the Northern Territory, and the southern McArthur Basin to the north. These surrounding regions host major base metal or gold deposits, contain units prospective for energy resources, and hold significant groundwater resources. The Georgina Basin has the greatest potential for groundwater.</div><div> </div><div>Geoscience Australia’s Exploring for the Future program provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia’s transition to net zero emissions, strong, sustainable resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government. More information is available at http://www.ga.gov.au/eftf and https://www.eftf.ga.gov.au/national-groundwater-systems.</div><div> </div><div>This model builds on the work undertaken in regional projects across energy, minerals and groundwater aspects in a collection of data and interpretation completed from the first and second phases of the EFTF program. The geological and geophysical knowledge gathered for energy and minerals projects is used to refine understanding of groundwater systems in the region.</div><div> </div><div>In this study, we integrated interpretation of a subset of new regional-scale data, which include ~1,900 km of deep seismic reflection data and 60,000 line kilometres of AusAEM1 airborne electromagnetic survey, supplemented with stratigraphic interpretation from new drill holes undertaken as part of the National Drilling Initiative and review of legacy borehole information (Figure 2). A consistent chronostratigraphic framework (Figure 3) is used to collate the information in a 3D model allowing visualisation of stacked Cenozoic Karumba Basin, Mesozoic Carpentaria Basin, Neoproterozoic to Paleozoic Georgina Basin, Mesoproterozoic Roper Superbasin (including South Nicholson Basin and Beetaloo Sub-basin of the southern McArthur Basin), Paleoproterozoic Isa, Calvert and Leichhardt superbasins (including the pre-Mesoproterozoic stratigraphy of the southern McArthur Basin) and their potential connectivity. The 3D geological model (Figure 4) is used to inform the basin architecture that underpins groundwater conceptual models in the region, constrain aquifer attribution and groundwater flow divides. This interpretation refines a semi-continental geological framework, as input to national coverage databases and informs decision-making for exploration, groundwater resource management and resource impact assessments.</div><div><br></div><div>This metadata document is associated with a data package including:</div><div>· Nine surfaces (Table 1): 1-Digital elevation Model (Whiteway, 2009), 2-Base Cenozoic, 3-Base Mesozoic, 4-Base Neoproterozoic, 5-Base Roper Superbasin, 6-Base Isa Superbasin, 7-Base Calvert Superbasin, 8-Base Leichhardt Superbasin and 9-Basement.</div><div>· Eight isochores (Table 4): 1-Cenozoic sediments (Karumba Basin), 2-Mesozoic sediments (Carpentaria and Eromanga basins), 3-Paleozoic and Neoproterozoic sediments (Georgina Basin), 4-Mesoproterozoic sediments (Roper Superbasin including South Nicholson Basin and Beetaloo Sub-basin), 5-Paleoproterozoic Isa Superbasin, 6-Paleoproterozoic Calvert Superbasin, 7-Paleoproterozoic Leichhardt Superbasin and 8-Undifferentiated Paleoproterozoic above basement.</div><div>· Five confidence maps (Table 5) on the following stratigraphic surfaces: 1-Base Cenozoic sediments, 2-Base Mesozoic, 3-Base Neoproterozoic, 4-Base Roper Superbasin and 5-Combination of Base Isa Superbasin/Base Calvert Superbasin/Base Leichhardt Superbasin/Basement.</div><div>· Three section examples (Figure 4) with associated locations.</div><div>Two videos showing section profiles through the model in E-W and N-S orientation.</div>
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<div>New SHRIMP U-Pb detrital zircon geochronology on Mesoproterozoic and Paleoproterozoic siliciclastic rocks from the South Nicholson region, in concert with recently acquired complementary regional geophysical datasets, has enabled comprehensive revision of the regional Proterozoic tectono-stratigraphy. The identification of analogous detrital zircon spectra between units deposited in half-graben hanging walls of major ENE-WSW trending extensional faults, the Benmara, Bauhinia, and Maloney-Mitchiebo faults, offers compelling evidence for regional tectono-stratigraphic correlation. Units sampled from the hanging walls of these faults are characterised by immature proximal lithofacies and host a small yet persistent population of <em>ca</em> 1640–1650 Ma aged zircon and lack Mesoproterozoic detritus, consistent with deposition coincident with extension during the River Extension event at <em>ca</em> 1640 Ma, an event previously identified from the Lawn Hill Platform in western Queensland. This finding suggests the hanging wall sequences are chrono-stratigraphically equivalent to the highly prospective sedimentary rocks of the Isa Superbasin, host to world-class sediment-hosted base metal deposits across western Queensland and north-eastern Northern Territory. Subsequent inversion of the extensional faults, resulted in development of south-verging thrusts, and exhumation of late Paleoproterozoic hanging wall siliciclastic rocks through overlying Mesoproterozoic South Nicholson Group rocks as fault propagated roll-over anticlines. These geochronology data and interpretations necessitate revision of the stratigraphy and the renaming of a number of stratigraphic units in the South Nicholson region. Accordingly, the distribution of the highly prospective late Paleoproterozoic units of the McArthur Basin, Lawn Hill Platform and Mount Isa Province is greatly expanded across the South Nicholson region. These findings imply that the previously underexplored South Nicholson region is a highly prospective greenfield for energy and mineral resources.</div> <b>Citation:</b> C. J. Carson, N. Kositcin, J. R. Anderson & P. A. Henson (2023) A revised Proterozoic tectono-stratigraphy of the South Nicholson region, Northern Territory, Australia—insights from SHRIMP U–Pb detrital zircon geochronology, <i>Australian Journal of Earth Sciences,</i> DOI: 10.1080/08120099.2023.2264355
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<div>The Sherbrook Supersequence (Campanian–Maastrichtian) is the youngest of four Cretaceous supersequences in the Otway Basin and was deposited during a phase of crustal extension. Supersequence thickness is typically less than 1000 ms TWT across the inboard platform. Beyond the platform edge up to 2 800 ms TWT of Sherbrook sediments were deposited in the deep-water Morum and Nelson sub-basins. Analysis of wireline-logs and cores from wells yielded fluvial, deltaic, coastal shelf gross depositional environments (GDEs). As the number of regionally mappable seismic facies is much less than the number of well-based GDEs, the integration of well-based environmental interpretations with seismic facies resulted in three main regional GDE (RGDE); Fluvial Plain, Coastal/Delta Plain, and Shelf. The Fluvial Plain and Coastal/Deltaic RGDEs are almost entirely restricted to the inboard platform areas of the basin. The mud-prone Shelf RGDE is widespread across the deep-water part of the basin where it forms the depocentres of the Morum and Nelson sub-basins. The Shelf RGDE is well imaged on the Otway 2020 2D seismic data that was acquired over the deep-water Otway Basin. In the Morum Sub-basin, the Shelf RGDE is strongly influenced by growth on extensional faults. In contrast, the Shelf RGDE in the Nelson Sub-bsin is a relatively unstructured progradational complex. The presence of mass-transport and incision complexes are consistent with active tectonism during Sherbrook deposition. Reservoir rocks in the deep-water basin are best developed in the Coastal/Deltaic RGDE where it encroaches into the Morum Sub-basin, and where the Austral 3 petroleum system was potentially active within the Sherbrook Supersequence. </div> This presentation was given at the 2023 Australasian Exploration Geoscience Conference (AEGC) 13-18 March, Brisbane (https://2023.aegc.com.au/)