The Layered Geology of Australia web map service is a seamless national coverage of Australia’s surface and subsurface geology. Geology concealed under younger cover units are mapped by effectively removing the overlying stratigraphy (Liu et al., 2015). This dataset is a layered product and comprises five chronostratigraphic time slices: Cenozoic, Mesozoic, Paleozoic, Neoproterozoic, and Pre-Neoproterozoic. As an example, the Mesozoic time slice (or layer) shows Mesozoic age geology that would be present if all Cenozoic units were removed. The Pre-Neoproterozoic time slice shows what would be visible if all Neoproterozoic, Paleozoic, Mesozoic, and Cenozoic units were removed. The Cenozoic time slice layer for the national dataset was extracted from Raymond et al., 2012. Surface Geology of Australia, 1:1 000 000 scale, 2012 edition. Geoscience Australia, Canberra.

The Officer Basin spanning South Australia and Western Australia is the focus of a regional stratigraphic study being undertaken as part of the Exploring for the Future (EFTF) program, an Australian Government initiative dedicated to increasing investment in resource exploration in Australia. Despite numerous demonstrated oil and gas shows, the Officer Basin remains a frontier basin for energy exploration with significant uncertainties due to data availability. Under the EFTF Officer-Musgrave Project, Geoscience Australia acquired new geomechanical rock property data from forty core samples in five legacy stratigraphic and petroleum exploration wells that intersected Paleozoic and Neoproterozoic aged intervals. These samples were subjected to unconfined compressive rock strength tests, Brazilian tensile strength tests and laboratory ultrasonic measurements. Petrophysical properties were also characterised via X-ray computerised tomography scanning, grain density and porosity-permeability analysis. Accurate characterisation of static geomechanical rock properties through laboratory testing is essential. In the modern exploration environment, these datasets are a precompetitive resource that can simplify investment decisions in prospective frontier regions such as the Officer Basin. Appeared in The APPEA Journal 62 S385-S391, 13 May 2022

The Solid Geology of the North Australian Craton web service delivers a seamless chronostratigraphic solid geology dataset of the North Australian Craton that covers north of Western Australia, Northern Territory and north-west Queensland. The data maps stratigraphic units concealed under cover by effectively removing the overlying cover (Liu et al., 2015). This dataset comprises five chronostratigraphic time slices, namely: Cenozoic, Mesozoic, Paleozoic, Neoproterozoic, and Pre-Neoproterozoic.

The Paleozoic alkaline and related igneous rocks of Australia web map service depicts the spatial representation of the alkaline and related rocks of Paleozoic age.

Building on newly acquired airborne electromagnetic and seismic reflection data during the Exploring for the Future (EFTF) program, Geoscience Australia (GA) generated a cover model across the Northern Territory and Queensland, in the Tennant Creek – Mount Isa (TISA) area (Figure 1; between 13.5 and 24.5⁰ S of latitude and 131.5 and 145⁰ E of longitude) (Bonnardot et al., 2020). The cover model provides depth estimates to chronostratigraphic layers, including: Base Cenozoic, Base Mesozoic, Base Paleozoic and Base Neoproterozoic. The depth estimates are based on the interpretation, compilation and integration of borehole, solid geology, reflection seismic, and airborne electromagnetic data, as well as depth to magnetic source estimates. These depth estimates in metres below the surface (relative to the Australian Height Datum) are consistently stored as points in the Estimates of Geophysical and Geological Surfaces (EGGS) database (Matthews et al., 2020). The data points compiled in this data package were extracted from the EGGS database. Preferred depth estimates were selected to ensure regional data consistency and aid the gridding. Two sets of cover depth surfaces (Bonnardot et al., 2020) were generated using different approaches to map megasequence boundaries associated with the Era unconformities: 1) Standard interpolation using a minimum-curvature gridding algorithm that provides minimum misfit where data points exist, and 2) Machine learning approach (Uncover-ML, Wilford et al., 2020) that allows to learn about relationships between datasets and therefore can provide better depth estimates in areas of sparse data points distribution and assess uncertainties. This data package includes the depth estimates data points compiled and used for gridding each surface, for the Base Cenozoic, Base Mesozoic, Base Paleozoic and Base Neoproterozoic (Figure 1). To provide indicative trends between the depth data points, regional interpolated depth surface grids are also provided for the Base Cenozoic, Base Mesozoic, Base Paleozoic and Base Neoproterozoic. The grids were generated with a standard interpolation algorithm, i.e. minimum-curvature interpolation method. Refined gridding method will be necessary to take into account uncertainties between the various datasets and variable distances between the points. These surfaces provide a framework to assess the depth and possible spatial extent of resources, including basin-hosted mineral resources, basement-hosted mineral resources, hydrocarbons and groundwater, as well as an input to economic models of the viability of potential resource development.

This service provides Estimates of Geological and Geophysical Surfaces (EGGS). The data comes from cover thickness models based on magnetic, airborne electromagnetic and borehole measurements of the depth of stratigraphic and chronostratigraphic surfaces and boundaries.

<p>The Paleozoic Canning Basin is a large (~720 000 km2) frontier province with several proven petroleum systems. Recent oil production from the Ungani field on the southern edge of the Fitzroy Trough has boosted the small-scale production of crude oil and gas discovered in the 1980s on the Lennard Shelf and flanking terraces (e.g. Blina, Boundary, Lloyd, Sundown, West Kora, West Terrace). Determining the paleo-depositional environments within the epicontinental seaway is essential to characterise source rock formation and distribution, and hence assist future exploration strategies.</p> <p>This study of diagnostic biomarker hydrocarbons derived from the coloured carotenoid pigments of photosynthetic organisms (including plants, algae, cyanobacteria and photosynthetic bacteria) was designed to extend the geochemistry of the Ordovician-, Middle to Late Devonian- and Early Carboniferous-sourced oils of the basin published by Edwards et al. (2013) and Spaak et al. (2017, 2018), and implemented by GeoMark Research. The focus was to clarify the paleo-depositional environment of their marine source rocks and the extent of water stratification, and to expand upon the diversity of the contributing organic matter. The oils on the Lennard Shelf and those on the southern side of the Fitzroy Trough (e.g. Ungani and Dodonea 1) preserve a diverse range of biomarkers, including both saturated and aromatic C40 carotenoid-derived compounds (Figure 1) due to minimal secondary alteration. All analysed oils contain the saturated biomarker beta-carotane, derived from algae and cyanobacteria that flourish in sunlit oxygenated water. In addition, the oils also contain aromatic carotenoids produced by photosynthetic green sulphur bacteria, which inhabit the photic zone of euxinic water columns (e.g. Summons & Powell, 1986; French et al., 2015). Paleorenieratane is the dominant C40 aromatic carotenoid in the Ordovician (Dodonea 1, Pictor) and Late Devonian-sourced oils (Blina 1, 2, 4 and Janpam North 1; Figure 1). Oils on the Lennard Shelf generated by Lower Carboniferous source rocks have variable distributions of carotenoids with isorenieratane either in similar concentration to paleorenieratane (Point Torment 1, Sundown 2), absent (West Kora 1) or, in the case of Terrace 1, in lower abundance relative to paleorenieratane. Paleorenieratane, isorenieratane and renieratane are absent in oils from Wattle 1 ST1 and Mirbelia 1. Chlorobactane, also derived from green sulphur bacteria, is present in many of the analysed oils (and is the dominant peak in Point Torment 1), whereas okenane (derived from purple sulphur bacteria) was not detected. The exception is the Late Ordovician (Sandbian) Cudalgarra 1 oil that contains a low concentration of okenane, and in which isorenieratane predominates over paleorenieratane. The aromatic carotenoid distribution in oil from Ungani 2 is similar to those from both Terrace 1 and Blina (Figure 1).</p> <p>The association of these saturated and aromatic carotenoids in Paleozoic Canning Basin oils provides evidence for long-term restricted circulation and the development of shallow chemoclines in an epicontinental seaway centred along the Fitzroy Trough and Gregory Sub-basin in which oxygenated surface water frequently overlaid deeper, anoxic, sulphidic (euxinic) water also within the photic zone.</p> <p>REFERENCES Edwards, D.S., Boreham, C.J., Chen, J., Grosjean, E., Mory, A.J., Sohn, J., Zumberge, J.E., 2013. Stable carbon and hydrogen isotopic compositions of Paleozoic marine crude oils from the Canning Basin: comparison with other west Australian crude oils. In: Keep, M., Moss, S. (Editors), The Sedimentary Basins of Western Australia IV, Perth, WA. Edwards, P., Streitberg, E., 2013. Have we deciphered the Canning? Discovery of the Ungani oil field. In: Keep, M., Moss, S. (Editors), The Sedimentary Basins of Western Australia IV, Perth, WA. French, K.L., Rocher, D., Zumberge, J.E., Summons, R.E., 2015. Assessing the distribution of sedimentary C40 carotenoids through time. Geobiology 13, 139–151, 10.1111/gbi.12126. Spaak, G., Edwards, D.S., Allen, H.J., Grotheer, H., Summons, R.E., Coolen, M.J.L., Grice, K., 2018. Extent and persistence of photic zone euxinia in Middle–Late Devonian seas – insights from the Canning Basin and implications for petroleum source rock formation. Marine and Petroleum Geology, 93, 33–56. Spaak, G., Edwards, D.S., Foster, C.B., Pagès, A., Summons, R.E., Sherwood, N., Grice, K., 2017. Environmental conditions and microbial community structure during the Great Ordovician Biodiversification Event; a multi-disciplinary study from the Canning Basin, Western Australia. Global and Planetary Change, 159, 93–112. Summons, R.E., Powell, T.G., 1986. Chlorobiaceae in Palaeozoic seas revealed by biological markers, isotopes and geology. Nature 319, 763–765.</p>

The Paleozoic alkaline and related igneous rocks of Australia web map service depicts the spatial representation of the alkaline and related rocks of Paleozoic age.

<b>This data package is superseded by a second iteration presenting updates on 3D geological and hydrogeological surfaces across eastern Australia that can be accessed through </b><a href="https://dx.doi.org/10.26186/148552">https://dx.doi.org/10.26186/148552</a> The Australian Government, through the National Water Infrastructure Fund – Expansion, commissioned Geoscience Australia to undertake the project ‘Assessing the Status of Groundwater in the Great Artesian Basin’ (GAB). The project commenced in July 2019 and will finish in June 2022, with an aim to develop and evaluate new tools and techniques to assess the status of GAB groundwater systems in support of responsible management of basin water resources. While our hydrogeological conceptual understanding of the GAB continues to grow, in many places we are still reliant on legacy data and knowledge from the 1970s. Additional information provided by recent studies in various parts of the GAB highlights the level of complexity and spatial variability in hydrostratigraphic units across the basin. We now recognise the need to link these regional studies to map such geological complexity in a consistent, basin-wide hydrostratigraphic framework that can support effective long-term management of GAB water resources. Geological unit markers have been compiled and geological surfaces associated with lithostratigraphic units have been correlated across the GAB to update and refine the associated hydrogeological surfaces. Recent studies in the Surat Basin in Queensland and the Eromanga Basin in South Australia are integrated with investigations from other regions within the GAB. These bodies of work present an opportunity to link regional studies and develop a revised, internally consistent geological framework to map geological complexity across the GAB. Legacy borehole data from various sources, seismic and airborne electromagnetic (AEM) data were compiled, then combined and analysed in a common 3D domain. Correlation of interpreted geological units and stratigraphic markers from these various data sets are classified using a consistent nomenclature. This nomenclature uses geological unit subdivisions applied in the Surat Cumulative Management Area (OGIA (Office of Groundwater Impact Assessment), 2019) to correlate time equivalent regional hydrogeological units. Herein we provide an update of the surface extents and thicknesses for key hydrogeological units, reconciling geology across borders and providing the basis for a consistent hydrogeological framework at a basin-wide scale. The new surfaces can be used for facilitating an integrated basin systems assessment to improve our understanding of potential impacts from exploitation of sub-surface resources (e.g., extractive industries, agriculture and injection of large volumes of CO2 into the sub-surface) in the GAB and providing a basis for more robust water balance estimates. This report is associated with a data package including (Appendix A – Supplementary material): • Nineteen geological and hydrogeological surfaces from the Base Permo-Carboniferous, Top Permian, Base Jurassic, Base Cenozoic to the surface (Table 2.1), • Twenty-one geological and hydrogeological unit thickness maps from the top crystalline basement to the surface (Figure 3.7 to Figure 3.27), • The formation picks and constraining data points (i.e., from boreholes, seismic, AEM and outcrops) compiled and used for gridding each surface (Table 3.8).

To meet the increasing demand for natural resources globally, industry faces the challenge of exploring new frontier areas that lie deeper undercover. Here, we present an approach to, and initial results of, modelling the depth of four key chronostratigraphic packages that obscure or host mineral, energy and groundwater resources. Our models are underpinned by the compilation and integration of ~200 000 estimates of the depth of these interfaces. Estimates are derived from interpretations of newly acquired airborne electromagnetic and seismic reflection data, along with boreholes, surface and solid geology, and depth to magnetic source investigations. Our curated estimates are stored in a consistent subsurface data repository. We use interpolation and machine learning algorithms to predict the distribution of these four packages away from the control points. Specifically, we focus on modelling the distribution of the base of Cenozoic-, Mesozoic-, Paleozoic- and Neoproterozoic-age stratigraphic units across an area of ~1.5 million km2 spanning the Queensland and Northern Territory border. Our repeatable and updatable approach to mapping these surfaces, together with the underlying datasets and resulting models, provides a semi-national geometric framework for resource assessment and exploration. <b>Citation:</b> Bonnardot, M.-A., Wilford, J., Rollet, N., Moushall, B., Czarnota, K., Wong, S.C.T. and Nicoll, M.G., 2020. Mapping the cover in northern Australia: towards a unified national 3D geological model. In: Czarnota, K., Roach, I., Abbott, S., Haynes, M., Kositcin, N., Ray, A. and Slatter, E. (eds.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, 1–4.