Development of a 3D continental chronostratigraphic framework for energy, minerals and groundwater integrated assessments

Introduction

Integrated and multidisciplinary geoscience is essential for the global transition to net zero and sustainability, enabling efficient resource assessment and management. Depth-based 3D geoscience data assists in discovering energy and mineral resources, understanding groundwater systems and identifying CO₂ and hydrogen storage sites. A unified continent-wide chronostratigraphic framework ensures consistent geological mapping across Australia’s diverse and interconnected onshore and offshore resources.

Geoscience Australia has advanced 3D mapping of sedimentary basins and aquifers using a regional chronostratigraphic framework (Fig. 1), supporting sustainable resource management and environmental impact assessments. This aligns with the Australian Government’s former Exploring for the Future (EFTF) program and the current Resourcing Australia’s Prosperity Initiative, a 35-year AU$3.4 billion investment in precompetitive geoscience to drive exploration, discoveries and responsible resource management.

Fig. 1.

Three-dimensional chronostratigraphic model of Australia. Surfaces: (a) DEM, (b) Base Cenozoic, (c) Base Mesozoic, (d) Base Devonian, (e) Base Ordovician, (f) Base Cambrian, (g) Base Neoproterozoic, (h) Base Paleoproterozoic. Isochores: (i) Cenozoic, (j) Mesozoic, (k) Ordovician–Silurian, (l) Cambrian, (m) Paleozoic, (n) Neoproterozoic, (o) Pre-Neoproterozoic, (p) Proterozoic. Gray indicates extent of unknown thickness. (q) Example of modelled cross-sections displayed over the Basement (Base Paleoproterozoic) surface. (r) Individual cross-section A–A′.

Using sequence stratigraphy principles, this approach integrates diverse frameworks into detailed 3D geological models, enhancing understanding of sedimentary basin-hosted minerals, energy, and groundwater systems across the continent. Adhering to the Findable, Accessible, Interoperable and Reusable data principles, it leverages tools like the Estimates of Geological and Geophysical Surfaces (EGGS) database and cover models (Bonnardot et al. 2024) to support resource exploration and environmental management.

Continental chronostratigraphic framework and hydrogeological surfaces

Australia’s sedimentary basins, ranging from Proterozoic to Cenozoic in age, host diverse minerals, energy and groundwater resources shaped by geological history. Their architecture and sediment fill influence groundwater flow and aquifer distribution, requiring consistent geological and hydrogeological mapping framework. A chronostratigraphic approach provides this consistency, enabling depositional sequence mapping and aquifer-aquitard delineation.

Initially applied to the Late Triassic–Cretaceous Great Artesian Basin (GAB) and the overlying Cenozoic Kati Thanda-Lake Eyre Basin (LEB), this methodology standardised time-equivalent geological unit correlations and hydrostratigraphic classifications across the Eromanga, Surat, and Carpentaria basins. Using the latest Geological Time Scale (Gradstein et al. 2020) and geochronological data (Rollet et al. 2022, 2024b; Hannaford and Rollet 2023), it aligns with hydrostratigraphic models from Queensland and South Australia, improving aquifer mapping and revealing previously unrecognised aquifers connections (Rollet et al. 2022, 2024a; Vizy and Rollet 2023). This approach adopts Santos’ hierarchical scheme (Mackie 2015) for Mesozoic and Cenozoic successions in central Australia and facilitates standardisation in wireline log interpretation, lithological variability assessments and aquifer-aquitard boundary revisions across the GAB (Rollet et al. 2022; Norton and Rollet 2023; Vizy and Rollet 2023; Vizy and Rollet 2024a).

Extended nationwide, this framework (Rollet et al. 2024a) now includes Jurassic–Cretaceous and Cenozoic basins in eastern Australia (Vizy and Rollet 2023), as well as older Paleozoic and Proterozoic basins, like Pedirka, Amadeus, Georgina, Officer, South Nicholson, southern McArthur (Rollet et al. 2024b; Vizy and Rollet 2024b) and Canning basins (Fig. 2). It refines nationwide stratigraphic and hydrostratigraphic correlations and classifications, improving 3D geological models, understanding of groundwater connectivity, resource assessments, supporting groundwater management and enabling comprehensive geoscientific analysis and informed decision-making.

Fig. 2.

Drillhole correlation transects (Norton and Rollet 2023): (a) location map across Australia, (b) example of cross-section plot from this study across the GAB with lithological variability in aquifers below the Wallumbilla Formation regional aquitard, calculated using the sand/shale ratio and flattened on the Top Cadna–owie–Bungil Formation horizon to show unit correlation and connectivity, and (c) updated hydrostratigraphic classification incorporating variability, with subdivisions based on Surat Basin and Eromanga Basin.

Compilation, collation and integration of data for consistent Australia-wide 3D mapping

Australia’s continental chronostratigraphic framework, developed in collaboration with states and territories, standardises geological and hydrogeological mapping by integrating diverse datasets, including drillholes, airborne electromagnetic (AEM) and seismic data (Fig. 3). This integration produces consistent 3D geological models and stratigraphic surfaces aligned to the Australian Height Datum, enhancing interpretations of basin architecture and resource potential.

Fig. 3.

Data sources used in this study with relative confidence values assigned between low to high: (a) drillhole formation picks compiled and reviewed for this current study and previously shared by QLD-OGIA and SA-DEW (dark green; high confidence) as well as from State and Territory petroleum wells and studies (light green; medium–high confidence) and water bores (orange; medium confidence); (b) AEM interpretation (low–medium confidence). (c) Seismic interpretation (low–medium confidence); (d) extracts from seismic and modelled surfaces (low confidence).

The Australian Borehole Stratigraphic Units Compilation (ABSUC; Vizy and Rollet 2024a) consolidates drillhole data from petroleum, mineral, water and stratigraphic sources. It refines over 1.1 million formation picks from 171,396 drillholes into 1.01 million high-confidence records, standardising stratigraphic units with the Australian Stratigraphic Units Database. ABSUC complements national frameworks and databases, such as the Bureau of Meteorology’s National Aquifer Framework, and Geoscience Australia’s drillhole database (BOREHOLE), improving the understanding of 3D basin architecture, aquifer geometry, and lithological variations.

An initial Australia-wide 3D geological model (Vizy et al. 2025) integrates interpretation of 1900 km of deep seismic reflection data, 130,000 line km of AEM conductivity sections and stratigraphic information from new drillholes undertaken as part of the National Drilling Initiative and review of legacy drillholes. Using a bottom-up approach, the model defines chronostratigraphic packages and aquifer-aquitard boundaries at 1000 m resolution, linking onshore and offshore sedimentary units across eight chronostratigraphic surfaces, from the Paleoproterozoic to the present (Fig. 1): (1) Top Basement (Base Paleoproterozoic), (2) Top Mesoproterozoic (Base Neoproterozoic), (3) Top Neoproterozoic (Base Paleozoic), (4) Top Cambrian (Base Ordovician), (5) Top Silurian (Base Devonian), (6) Top Permian (Base Mesozoic), (7) Top Cretaceous (Base Cenozoic) and (8) Digital Elevation Model (DEM) (Ground surface). These surfaces are used to populate the Geoscience Australia’s EGGS database, supporting resource assessments, groundwater studies and CO₂–hydrogen storage targets. Associated thickness maps (isochores) reveal key resource layers distribution and depth across major basins (Vizy et al. 2025).

Key basins, including the GAB, LEB, Pedirka, Galilee, Cooper, Canning, Georgina, Amadeus and Officer basins, are subdivided into additional packages to further delineate hydrostratigraphic groupings. The extended GAB model includes 18 surfaces across eastern Australia, enhancing nationwide sedimentary basin understanding. These models refine groundwater frameworks, identify data gaps and guide future acquisitions to improve confidence, ensuring consistent resource mapping and sustainable resource management.

Applications of 3D models

The integration of 3D geological models into a consistent national framework enables diverse geological and water resource applications. A range of investigations using the data and models are cited in Rollet et al. (2024a), including:

These models enhance resource assessments, storage evaluations and groundwater management, supporting Australia’s sustainable development.

Conclusion and recommendations

Geoscience Australia, through the former EFTF program and current Resourcing Australia’s Prosperity Initiative, is advancing the state of subsurface geological knowledge to support sustainable resource development and groundwater system understanding across Australia. By integrating geoscientific data into 3D geological models within a chronostratigraphic framework, consistent interpretations support research, resource planning, infrastructure, and environmental monitoring.

Key priorities include:

Regular updates to 3D models are crucial for resource assessments, environmental sustainability and informed policies.