This web service provides access to geological, hydrogeological and hydrochemical digital datasets that have been published by Geoscience Australia for the Great Artesian Basin (GAB).

The National Groundwater Systems (NGS) project, is part of the Australian Government’s Exploring for the Future (EFTF) program, led by Geoscience Australia (https://www.eftf.ga.gov.au/national-groundwater-systems), to improve understanding of Australia’s groundwater resources to better support responsible groundwater management and secure groundwater resources into the future. The project is developing new national data coverages .to further delineate groundwater systems and improve data standards and workflows of groundwater assessment. While our conceptual understanding of the hydrogeology of the Great Artesian Basin (GAB, Figure 1) continues to grow, in many parts of the Eromanga, Surat and Carpentaria basins that form the GAB we are still reliant on legacy data and knowledge from the 1970s of variable quality. Additional information provided by recent studies in various parts of the GAB highlights the level of architectural complexity and spatial variability in stratigraphic and hydrostratigraphic units across the basin. We now recognise the need to standardise 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. The recent iteration of revision of GAB geological and hydrogeological surfaces (Vizy & Rollet, 2022) provides a framework to interpret various data sets consistently (e.g., boreholes, airborne electromagnetic, seismic data) and in a 3D domain, to improve the aquifer geometry, and the lateral variation and connectivity in hydrostratigraphic units across the GAB (Rollet et al., 2022). Vizy and Rollet (2022) highlighted some areas with low confidence in the interpretation of the GAB where further data acquisition or interpretation may reduce uncertainty in the mapping. One of these areas was in the Carpentaria Basin, particularly the transition from the offshore to onshore across the Gulf of Carpentaria. This data compilation provides open file SEGY, cultural data and value added seismic interpretation in the form of seismic horizons and grids for two key surfaces, these enable improved correlation to existing studies. This data also aim to provide users an efficient mean to rapidly access core data from numerous sources in a consistent and cleaned format, all in a single package. This dataset provides: 1) Seismic data compilation in a digital format with publically accessible information, including scanned seismic sections converted to SEGY format where digital data was not available; 2) Base Mesozoic and Near Base Cenozoic seismic interpretation in two-way-time; 3) Depth converted regional surfaces for the Base Mesozoic and Near Base Cenozoic unconformities generated using additional constraints such as AEM interpretation and borehole constraints previously compiled in Vizy & Rollet (2022). This new interpretation will be used to refine the GAB geological and hydrogeological surfaces in this region.

<div>This Geoscience Australia Record reports on Interferometric Synthetic Aperture Radar (InSAR) processing over the Great Artesian Basin (GAB) to support an improved understanding of the groundwater system and water balance across the region. InSAR is a geodetic technique that can identify ground surface movement from satellite data at a regional scale and is therefore a valuable and widely used technique for measuring patterns in surface movement over time; including the movement of fluids (i.e. water or gas) beneath the surface.</div><div><br></div><div>This Record is the one of two Geoscience Australia Records that describe ground surface movement monitoring Geoscience Australia have undertaken in the GAB in recent years. Namely;</div><div>1.&nbsp;&nbsp;&nbsp;&nbsp;Ground surface movement in the northern Surat Basin derived from campaign GPS measurements. (Garthwaite et al., 2022).</div><div>2.&nbsp;&nbsp;&nbsp;&nbsp;InSAR processing over the Great Artesian Basin and analysis over the western Eromanga Basin and northern Surat Basin (this Record).</div><div><br></div><div>We have produced ground surface motion data products, which cover about 90% of the GAB for the period of time between January 2016 and August 2020. The data products were created using Sentinel-1 Synthetic Aperture Radar (SAR) data and an InSAR processing workflow designed for large spatial scale processing. The large spatial scale InSAR processing workflow includes using GAMMA software to (i) pre-process SAR images to align the pixels, (ii) generate interferograms and short temporal baseline surface displacement maps and PyRate software to (iii) combine these outputs in an inversion to form pixel-wise time series ground surface displacement data and fit ground surface velocities to the displacement data. The raw SAR data and these subsequent data products of the workflow are partitioned into overlapping frames; the final stage of the large scale processing workflow is to combine the partitioned data into a single map using a mosaicking algorithm. The results of this processing chain demonstrate the feasibility of developing a regional scale ground surface movement reconnaissance tool (i.e. subsidence and uplift). </div><div><br></div><div>We provide a summary of the processing chain and data products and a focused assessment for two case study areas in the western Eromanga Basin (South Australia) and northern Surat Basin (Queensland). Over these case study areas we examine the relationship between the InSAR derived ground surface movement and available groundwater level data. We also assess how land use types may influence the InSAR derived ground surface motion data by comparing the InSAR data to the “land types” over the region which we classify using a machine learning algorithm with Sentinel-2 optical imagery data. </div><div><br></div><div>From our analysis we observe little ground surface motion over the western Eromanga Basin. The surface movement rate over the entire area is estimated to be mostly within ±10 mm/yr. Groundwater level time series data from well monitoring sites in the area did not appear to have any significant trends either. However, large and broad scale ground surface motion (both uplift and subsidence) was observed in the InSAR processing results over the northern Surat Basin. A 75 km x 150 km scale uplift signal, with rates of up to 20 mm/yr, was located over an area we classified as cultivated land, where InSAR signals are likely to be influenced by near-surface cultivation activities (such as irrigation) rather than subsurface groundwater level changes. Furthermore, two approximately 75km x 75 km areas were identified which had subsidence signals of up to -20 mm/yr. Over the same area, groundwater level time series data show long-term negative trends in the water head level. For a more direct comparison between the InSAR results and the well data, we fitted a first order poroelastic model to transform the InSAR derived ground surface motion rates into modelled pore-pressure decline/groundwater drawdown rates. We compared the model to the groundwater time series data in the Walloon Coal Measures, Surat Basin, and found good agreement, which indicates that the observed subsidence signals could be attributable to pore-pressure decline due to the falling water head level.</div><div><br></div><div>We finally provide some preliminary analysis comparing our InSAR results to the results from an Office of Groundwater Impact Assessment (OGIA) InSAR study and a Geoscience Australia GPS land movement study to assist in validating the Geoscience Australia InSAR results. Overall, the comparisons are encouraging, showing a high correlation against the OGIA InSAR results and GPS results. Further work, is required to further validate our results and reduce uncertainty in our analysis process.</div>

This report presents the results of an assessment of geoscience data and tools applied in the eastern Eromanga Basin to improve the hydrogeological conceptualisations. The assessment is one component of the Australian Government funded project ‘Assessing the Status of Groundwater in the Great Artesian Basin’. The results demonstrate that the application of existing and new geoscientific data and technologies has the potential to further improve our understanding of the Great Artesian Basin (GAB) hydrogeological system thus supporting the responsible management of basin water resources. Hydrogeological synthesis using airborne electromagnetic data, in conjunction with hydro- and chrono-stratigraphic data and well geological information, are effective at mapping the three dimensional distribution of the aquifers and aquitards. The results lead to an improved understanding of groundwater intake bed geometry, potential connectivity between aquifers, possible structural controls on groundwater flow paths, and plausible source of groundwater discharging as springs. In the southern part of the study area, the dominantly shale-rich Evergreen Formation is electrically conductive, but is locally resistive in places due to sand-rich facies. These areas allow hydraulic connectivity between the overlying and underlying Hutton and Precipice sandstone aquifers. Anticlinal folds and juxtaposed strata are observed on AEM traverses along the strike of the aquifer units, and includes the Hutton, Adori and Cadna-owie – Hooray sandstones. Abrupt folding and juxtaposed strata were interpreted as fault zones. Both structural features have the potential of controlling groundwater flow directions or groundwater storage compartmentalisation. The northern limits of Precipice Sandstone and Evergreen Formation are at Blackall and south of Barcaldine towns respectively. This zone also coincides with the southern edge of the east-west trending sub-surface Barcaldine Ridge where the basal Jurassic sequence abut against. On and north of the Barcaldine Ridge, the Cadna-owie – Hooray, Adori and Hutton sandstones are present. Mapping using AEM conductivity sections affirm that the Hutton Sandstone is the major aquifer in the northern part of the study area. The Poolowanna Formation, an age equivalent to the Evergreen Formation and Precipice Sandstone, is laterally extensive towards the northern part of the study area. This formation crops-out west of Lake Buchanan in the Great Dividing Range, but forms sub-crops elsewhere along the groundwater recharge areas. Numerous groundwater springs and spring clusters are present along the east and west of the outcropping sandstone hills in the Great Dividing Range. In the northern parts of the study area, source of groundwater for the springs are mainly derived from the Hutton Sandstone aquifers through either gravity-feed or lateral groundwater flow process. Polygonal faults mainly occur on conductive and fined-grained sedimentary units of the Rolling Downs Group. There is lack of observable evidence from AEM conductivity sections on the presence of polygonal faults to suggest preferential groundwater flows along these potential hydraulic conduits. Further investigation using ground based methods are needed to establish the presence of the faults and their hydraulic properties.

The Australian Government, through the National Water Infrastructure Development Fund, commissioned Geoscience Australia to undertake a 3-year project ‘Assessing the Status of Groundwater in the Great Artesian Basin’. The overall aim of the project was to analyse existing and new geoscientific data acquired by the project to improve understanding of the hydrogeological system and water balance in the GAB. In conjunction, the project assessed satellite based technologies for monitoring groundwater storage and level change. This talk will discuss some of the key results of the project. These include: an updated hydrogeological framework for the GAB, mapping aquifer and aquitard properties, geometry and extent; revised groundwater recharge rate estimates in the eastern GAB groundwater intake beds; new groundwater system conceptual models of groundwater recharge processes and groundwater flow; an assessment of the Gravity Recovery and Climate Experiment (GRACE) satellite derived groundwater storage change estimates for the GAB; and Interferometric Synthetic Aperture Radar (InSAR) satellite data, for detecting changes in groundwater levels.

<div>Understanding groundwater flow dynamics within the Great Artesian Basin (GAB) is critical for responsible management of groundwater from an environmental, economic and cultural perspective. Numerical groundwater flow modelling involves generating a simplified representation of a groundwater system and using Darcy’s Law to simulate groundwater flow rates and the distribution of hydraulic heads throughout the system. This is a pilot study aimed at developing a workflow for groundwater flow modelling of the Great Artesian Basin using Bayesian methods. In this report, we present our initial results from building and running a steady-state groundwater flow model of the entire GAB. We demonstrate a Bayesian inference framework to generate an ensemble of groundwater flow models allowing an assessment of the uncertainty of model parameters and flow velocities.&nbsp;</div><div>Several models have been built to simulate groundwater flow across various areas and layers of the GAB. Most of these models aimed to predict the likely impacts on the groundwater system of some future scenario, generally climate change or groundwater extraction relating to mining activities. While these models are well-suited to their purpose, their focus on particular regions or aquifers makes them unsuitable for investigating large-scale groundwater flow throughout the GAB. In contrast, the model built as part of this study captures the entire GAB and aims to simulate large-scale flow. Although not in scope for this pilot study, the questions a model at this scale is capable of addressing include characterising 3D flow within hydrogeological layers, computing groundwater flux between aquifers and between sub-basins, inferring hydraulic properties and identifying poor quality data. As this model is steady-state and uses hydraulic head data from before the year 2000, it provides a baseline estimate of groundwater flow without considering recent anthropogenic forcing or transient system stresses.&nbsp;</div><div>The GAB is represented as a 14 hydrogeological layer model including basement, Permo-Carboniferous basins, Mesozoic sedimentary aquifers and aquitards and Cenozoic layers. This includes updated hydrogeological surfaces from the GAB project. The input data consisted of 8,065 hydraulic head measurements and 6,151 estimates of recharge rate while the model parameters were a single hydraulic conductivity value for each of the 14 layers. The modelling domain was discretised using 10 x 10 km cells in the horizontal plane and the mesh was deformed vertically to fit between the topography and the basement surface, with the resulting mesh having a vertical discretisation of no coarser than 50 metres. The top boundary condition was a constant head boundary that was a smoothed version of topography. The sides and bottom of the model have no flux boundary conditions and a buffer zone around the GAB was included to minimise boundary effects.&nbsp;&nbsp;</div><div>In total 2500 groundwater flow simulations were run using a Bayesian inversion framework. The inversion sampled various combinations of input parameters to find models with a relatively low misfit, which was calculated by squaring the difference between the observed and simulated values of hydraulic head and recharge. Rather than searching for a global minima, the Metropolis Hastings Markov Chain Monte Carlo sampling algorithm was used to explore a range of possible models and estimate the posterior distribution of each layer’s hydraulic conductivity.&nbsp;</div><div>The model performed adequately and the model parameters were generally consistent with the prior probability distributions based on previous modelling studies. However, the posterior distribution of model parameters were very broad indicating the model was not particularly informative in its current form.&nbsp;&nbsp;</div><div>Groundwater flow velocity vectors from the maximum likelihood model were used to investigate groundwater trends within the Cadna-owie-Hooray aquifer. Uncertainty of model predictions were investigated by calculating the groundwater flow velocity variance across the ensemble. This study demonstrates that it is technically feasible to use Bayesian inference to probabilistically mode groundwater flow across the entire GAB. However, for this approach to yield useful results, more work is required to understand the impacts of simplifying assumptions about layer properties, the quality of the input data and model structure on the resulting flow model.&nbsp;</div><div><br></div>

This report presents a stratigraphic review of some key boreholes across the Jurassic-Cretaceous Eromanga, Surat and Carpentaria basins that form the groundwater Great Artesian Basin (GAB), as well as across the overlying Cenozoic Lake Eyre Basin (LEB), completed during the National Groundwater Systems (NGS) Project. The NGS Project is part of Exploring for the Future (EFTF)—an eight year, $225 million Australian Government funded geoscience data and information acquisition program focused on better understanding the potential mineral, energy and groundwater resources across Australia. The study presented here builds on previous work (Norton & Rollet, 2022a) undertaken as part of the ‘Assessing the Status of Groundwater in the Great Artesian Basin’ Project, commissioned by the Australian Government through the National Water Infrastructure Fund – Expansion. Although not intended to be a major re-interpretation of existing data, this stratigraphy review updates stratigraphic picks where necessary to obtain a consistent interpretation across the study area, based on the refined geological and hydrostratigraphical framework developed through this project. Problems and inconsistencies in the input data or current interpretations have been highlighted to suggest where further studies or investigations may be useful. This study includes Phase 2 of the National Groundwater Systems Project, which was undertaken by Catherine Jane Norton in collaboration with Geoscience Australia; and compiled, processed and correlated a variety of borehole log data to review the stratigraphy and improve the understanding of distribution and characteristics of Jurassic and Cretaceous sediments across the Eromanga and Surat basins and overlying LEB. To complement the previous 322 key boreholes compiled in Phase 1 (Norton & Rollet, 2022) additional stratigraphic correlations have been made between geological units of similar age (constrained using palynological data) from 706 key boreholes along 35 regional transects across the GAB and from 406 key boreholes along 20 regional transects across the central LEB. Also included in this study is Phase 3 in-fill work of four additional transects, extending the study further south in New South Wales, to tie in to the Cenozoic of the Murray Basin. This later phase 3 of the project also included a review and quality control of approximately 2,572 central LEB boreholes, and the addition of 278 boreholes in the GAB in southern Queensland and New South Wales. Phase 3 also expanded on the results used for mapping regional sand/shale ratios that began in the previous phase (Evans et al., 2020; Norton & Rollet, 2022a). Normalised Gamma Ray (GR) calculations have now been made for 1,778 LEB boreholes and 676 GAB boreholes spanning the entire sequence from the surface, through the Cenozoic and down to the base Jurassic unconformity. The previous phase, mentioned above, concentrated on either just the LEB or the GAB intervals from Cadna-owie Formation to base Jurassic. An additional 17 transects in the LEB and 27 transects in the GAB were created to visualise the lithological variation. The distribution of generalised sand/shale ratios are used to estimate the thickness of sand and shale in different formations, with implications for formation porosity and the hydraulic properties of aquifers and aquitards. This study fills data gaps identified in the previous study (Norton & Rollet, 2022) and refines the regional distribution of lithological heterogeneity in each hydrogeological unit, contributing to an improved understanding of connectivity within and between aquifers. The datasets compiled and examined in this study are in Appendix A. Attempts were made to standardise lithostratigraphic units, which are currently described using varying nomenclature, to produce a single chronostratigraphic chart across the entirety of the GAB and LEB basins. The main stratigraphic correlation infill in the GAB and LEB regions focused on: • The transition between the Eromanga and Surat basins in New South Wales and the tie-in to existing transects in Queensland and South Australia, • The Eromanga Basin in South Australia and Queensland and the tie-in to Phase 1 transects, • The central Eromanga Basin and Frome Embayment areas, extending the GAB units to the overlying Lake Eyre Basin stratigraphy to better assess potential connectivity between these basins, • The transition between the Lake Eyre and Murray Basins in the Upper Darling Floodplain (UDF) area in New South Wales and the tie-in to Phase 1 transects in New South Wales. This report and associated data package provide a data compilation on 706 and 278 key boreholes in the Surat and Eromanga basins respectively, to assist in updating the geological framework for the GAB and LEB. Recommendations are provided for further studies to continue refining the understanding of the stratigraphy in the Great Artesian and Lake Eyre basins.

<div><strong>Output Type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short Abstract: </strong>Australia's Great Artesian Basin (GAB) is a vital groundwater system extending across parts of Queensland, New South Wales, South Australia, and the Northern Territory, crucial for community water supplies, economic development, indigenous cultural values and groundwater dependent ecosystems. Managing GAB groundwater poses challenges due to the complex structure of the sedimentary basin, requiring a better understanding of aquifers, aquitards, and hydraulic connections at a whole GAB scale. Additionally, inconsistencies in nomenclature and subdivisions across the basin further complicate the definition and description of these strata. This study employs an integrated basin analysis workflow using new and existing data to create a 3D geological model tied to a consistent chronostratigraphic framework and State and Territory hydrostratigraphic classifications. The model refines the characteristics of 18 hydrogeological units, offering insights into aquifer boundaries and connectivity. This comprehensive approach enhances the 'whole-of-Basin' subsurface geological understanding, benefiting groundwater management, resource assessments, uncertainty risk assessment and environmental impact assessments across multiple jurisdictions and the broader resource sector (e.g., Carbone Capture and Storage and hydrogen).</div><div><br></div><div><strong>Citation: </strong>Rollet, N., Vizy, J., Norton, C.J., Hannaford, C., McPherson, A., Symington, N., Evans, T., Bradshaw, B., Szczepaniak, M., Bui Xuan Hy, A., Schoning, G. &amp; Keppel, M., 2024. Great Artesian Basin 3D chronostratigraphic model: providing new insights into hydrogeological variability and connectivity. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts. Geoscience Australia, Canberra, https://doi.org/10.26186/149235</div>

<div>This document provides metadata for the gross depositional environment (GDE) interpretations that have been generated in support of the energy resource assessments under the Australia’s Future Energy Resources (AFER) project.&nbsp;&nbsp;</div><div>The AFER projects is part of Geoscience Australia’s Exploring for the Future (EFTF) Program—an eight year, $225 million Australian Government funded geoscience data and precompetitive information acquisition program 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 will help support a strong economy, resilient society and sustainable environment for the benefit of all Australians. The EFTF program is supporting Australia’s transition to a low emissions economy, industry and agriculture sectors, as well as economic opportunities and social benefits for Australia’s regional and remote communities. Further details are available at http://www.ga.gov.au/eftf.&nbsp;</div><div>The GDE data sets provide high level classifications of interpreted environments where sediments were deposited within each defined play interval in the Pedirka, Simpson and Western Eromanga basins. Twelve gross depositional environments have been interpreted and mapped in the study (Table 1). A total of 14 play intervals have been defined for the Pedirka, Simpson and Western Eromanga basins by Bradshaw et al. (2022, in press), which represent the main chronostratigraphic units separated by unconformities or flooding surfaces generated during major tectonic or global sea level events (Figure 1). These play intervals define regionally significant reservoirs for hydrocarbon accumulations or CO2 geological storage intervals, and often also include an associated intraformational or regional seal.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</div><div>GDE interpretations are a key data set for play-based resources assessments in helping to constrain reservoir presence. The GDE maps also provide zero edges showing the interpreted maximum extent of each play interval, which is essential information for play-based resource assessments, and for constructing accurate depth and thickness grids.&nbsp;&nbsp;</div><div>GDE interpretations for the AFER Project are based on integrated interpretations of well log and seismic data, together with any supporting palynological data. Some play intervals also have surface exposures within the study area which can provide additional published paleo-environmental data. The Pedirka, Simpson and Western Eromanga basins are underexplored and contain a relatively sparse interpreted data set of 42 wells and 233 seismic lines (Figure 2). Well and outcrop data provide the primary controls on paleo-environment interpretations, while seismic interpretations constrain the interpreted zero edges for each play interval. The sparse nature of seismic and well data in the study area means there is some uncertainty in the extents of the mapped GDE’s.&nbsp;&nbsp;</div><div>The data package includes the following datasets:&nbsp;&nbsp;</div><div>Play interval tops for each of the 42 wells interpreted – provided as an ‘xlsx’ file.&nbsp;</div><div>A point file (AFER_Wells_GDE) capturing the GDE interpretation for each of the 14 play intervals in each of the 42 wells – provided as both a shapefile and within the AFER_GDE_Maps geodatabase.&nbsp;</div><div>Gross depositional environment maps for each of the 14 play intervals (note that separate GDE maps have been generated for the Namur Sandstone and Murta Formation within the Namur-Murta play interval, and for the Adori Sandstone and Westbourne Formation within the Adori-Westbourne play interval) – provided as both shapefiles and within the AFER_GDE_Maps geodatabase.&nbsp;</div><div>&nbsp;</div><div>These GDE data sets are being used to support the AFER Project’s play-based energy resource assessments in the Western Eromanga, Pedirka and Simpson basins.&nbsp;</div><div><br></div>

This report presents palynological data compiled and analysed as part of Geoscience Australia’s ‘Assessing the Status of Groundwater in the Great Artesian Basin’ project, commissioned by the Australian Government through the National Water Infrastructure Fund – Expansion. Diverse historic nomenclature within the Great Artesian Basin (GAB) Jurassic‒Cretaceous succession in different parts of the GAB makes it difficult to map consistently GAB resources across borders, at a basin-wide scale, in order to provide a geological and hydrogeological framework to underpin effective long-term management of GAB water resources. The study undertaken by MGPalaeo, in collaboration with Geoscience Australia, examined 706 wells across the GAB and compiled 407 wells, having Jurassic‒Cretaceous succession, with reviewed palynology data (down to total depth). This initial palynology data review allowed identification of new data samples from 20 wells (within the 407 wells) in Queensland and South Australia to fill data and knowledge gaps within the Jurassic‒Cretaceous GAB succession. This study resulted in: 1) a summary compilation of existing palynology data on 407 wells selected to create a regional framework between the Surat, eastern Eromanga and western Eromanga basins, to help regional correlations across the GAB, 2) a review of several different palynology zonation schemes and adaptation to a single consistent scheme, applying the scheme of Price (1997) for the spore pollen zonation and Partridge (2006) for the marine zonation, 3) updated stratigraphic charts across the Surat, Eromanga and Carpentaria basins, 4) identification of data and knowledge gaps, and 5) sampling of new palynology data to help fill some data and knowledge gaps identified in 13 key wells in the Surat Basin and 10 key wells in the Eromanga Basin. In the Surat Basin the new sampling program has targeted units within: the Evergreen Formation, Hutton Sandstone, Springbok Sandstone, Gubberamunda Sandstone, Orallo Formation, Mooga Sandstone, Bungil Formation. In the Eromanga Basin the sampling program targeted units within: the Poolowanna Formation, Hutton Sandstone, Adori Sandstone, Algebuckina Sandstone, Namur Sandstone and Hooray Sandstone. The study undertaken by MGPalaeo, in collaboration with Geoscience Australia, provides updated biostratigraphic information compiled in a standardised chronostratigraphic framework across the Surat, Eromanga and Carpentaria basins that mostly comprise the GAB. This work allows comparison of various geological, lithological, hydrogeological schemes. It provides links between various lithostratigraphic units, with different nomenclature, across jurisdictions. It also links these units to some key regional chronostratigraphic markers that can be used to generate consistent surfaces that correlate to aquifer and aquitard boundaries. The compilation of legacy and newly sampled and analysed palynology data allows refinement of a regional chronostratigraphic framework that can be used to map a common Mesozoic play interval scheme across all the resource types, for basin-scale assessments of groundwater, hydrocarbons, carbon capture and storage, and mineral potential. From this correlation of time equivalent geological units deposited in different environments, it is then possible to map internal lithological variations in stratigraphic facies within sequences that influence hydraulic properties and connectivity within and between aquifers across the GAB. The updated geometry and variability mapping within and between aquifers will help refine the conceptual hydrogeological model, to assess how aquifers and aquitards are connected within the GAB. The revised conceptual hydrogeological model can facilitate an improved understanding of potential impacts from exploitation of sub-surface resources in the basin, providing a basis for more robust water balance estimates.