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  • It is generally accepted that the near surface search space for mineral deposits in Australia and elsewhere in the world has been well explored and the frontier of exploration lies beneath post-mineralisation cover. The Exploring for the Future program aims to unlock this new search space in northern Australia and parts of southern Australia by reducing the technical risk of mineral exploration through the provision of innovative pre-competitive data and information. The first step to de-risk undercover exploration is to simply define the depth to prospective rocks as cover-thickness places first order constraints on the economic search space. With this aim in mind we present a preliminary model of the depth to pre-Neoproterozoic rocks between Tennant Creek and Mt Isa, an area of focused integrated studies of the Exploring for the Future program. This work aims to compliment recent and ongoing mineral potential assessments in this region, which suggest covered pre-Neoproterozoic rocks are prospective for iron oxide-copper-gold and sediment hosted base metal mineral deposits. Our model utilises a dasets of over eight four thousand point estimates of the depth to pre- Neoproterozoic strata from boreholes, reflection seismic profile interpretations and depth to magnetic top estimates mostly sourced from the new Estimates of Geological and Geophysical Surfaces database supplemented by the distribution of pre-Neoproterozoic strata outcrops. These constraints were objectively queried based on their reliability, subsampled at 0.05 degrees and gridded using an adjustable tension continuous curvature-surfacing algorithm. The result shows Palaeozoic cover-thickness generally increases away from outcrops with a notable exception east of Tennant Creek where cover-thickness is typically less than 250 m thick. Fortuitously, this region of shallow cover termed the East Tennant Ridge corresponds with a region recently assess to have potential to host iron oxide-copper-gold mineralisation.

  • This Record documents the efforts of the Geological Survey of Victoria (GSV) and Geoscience Australia (GA) in compiling a geochronology (age) compilation for Victoria, describing both the dataset itself and the process by which it is incorporated into the continental-scale Isotopic Atlas of Australia. The Isotopic Atlas draws together age and isotopic data from across the country and provides visualisations and tools to enable non-experts to extract maximum value from these datasets. Data is added to the Isotopic Atlas in a staged approach with priorities determined by GA- and partner-driven focus regions and research questions. This dataset, which was primarily compiled by GSV and has been supplemented with data compiled by GA during the 2013–2017 Stavely Project, is a foundation for the second phase of the Exploring for the Future initiative over 2020–2024, particularly the Darling-Curnamona-Delamerian Project.

  • As Australia and the world transition to net zero emissions, hydrogen will continue to grow in importance as a clean energy source, with underground hydrogen storage (UHS) expected to be a key component of this new industry. Salt (halite) caverns are a preferred storage option for hydrogen, given their scale, stability and the high injection and withdrawal rates they can support. The use of salt caverns for storing gas is an established industry in North America and Europe but not in Australia, where exploration for suitable storage locations is in the initial frontier stages. Australia’s known major halite deposits occur in Neoproterozoic and Paleozoic sequences and are predominantly located in western and central Australia. This analysis has identified potential in eastern Australia in addition to the proven thick halite in the Adavale Basin, Queensland. Building on Geoscience Australia’s previous salt studies in the Canning, Polda and Adavale basins, this study expands the portfolio of areas prospective for halite in onshore and offshore basins using both direct and indirect evidence. The study correlates paleogeography and paleoclimate reconstructions with evidence of salt in wells, and in geophysical and geochemical data. Salt cavern design for UHS, the solution mining process, and the preferred salt deposits are also discussed. The results will provide pre-competitive information through a comprehensive inventory of areas that may be prospective for UHS. Published in The APPEA Journal 63 285-304 https://doi.org/10.1071/AJ22153

  • This report presents a summary of the groundwater hydrochemistry data release from the Western Davenport project conducted as part of Exploring for the Future (EFTF). This data release records the groundwater sample collection methods and hydrochemistry and isotope data from monitoring bores in the Western Davenport project area, Northern Territory (NT). The Western Davenport project is a collaborative study between Geoscience Australia and the NT Government. Hydrochemistry and isotope data were collected from existing and newly drilled bores in the Western Davenport area.

  • The Western Davenport region has been identified as an area of interest for future agricultural development. However, realisation of this potential depends on access to a reliable supply of groundwater, underpinned by rigorous geological and groundwater information. A three-dimensional stratigraphic model has been created for the Western Davenport area of the Southern Stuart Corridor project under the Exploring for the Future program. Our interpretation integrates airborne electromagnetic data with historical drillhole and outcrop data to improve geological and hydrogeological understanding. Results show that stratigraphies of the Wiso and Georgina basins are equivalent and laterally continuous in this area. This enables a more complete hydrostratigraphy to be defined and underpins improved hydrogeological conceptualisation. New hydrochemical data support the conceptual model that the aquifers of the Wiso and Georgina basins are interconnected at a regional scale. The initial assessment of water quality indicates that groundwater may support further agricultural development. Analysis of new water chemistry data has improved understanding of groundwater processes and potential areas of recharge. This work will inform management decisions to enhance the economic and social opportunities in the Western Davenport area, while protecting the environmental and cultural value of water resources. <b>Citation:</b> Northey, J.E., Clark, A.D., Smith, M.L. and Hostetler, S., 2020. Delineation of geology and groundwater resources in a frontier region: Western Davenport, Northern Territory. 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.

  • The Adavale Basin, home to the Boree Salt, is a potential option for underground hydrogen storage (UHS) due to its close proximity to industrial infrastructure, existing pipelines and significant renewable energy sources. This study builds upon a previously constructed 3D geological model to examine the feasibility of developing salt caverns for UHS. The study integrates well data and regional geology, as well as analyses on mineralogy, geochemistry and petrophysical and geomechanical properties of the Boree Salt. Results highlight that the Boree Salt is predominantly halite (96.5%), with a net salt thickness of ~540 m encountered in Bury 1, and has excellent seal properties. Furthermore, the formation overburden pressure gradient implies favourable conditions for storing hydrogen in the Boree Salt. To illustrate the feasibility of UHS, a conceptual design of a cylindrical salt cavern at depth intervals of 1600 – 1950 m is presented. A single 60 m diameter cavern could provide up to 203 GWh (or ~ 6000 tonnes) of hydrogen energy storage. Further investigation to improve our understanding on the Boree Salt extent is recommended.

  • This Galilee Basin dataset contains descriptive attribute information for the areas bounded by the relevant spatial groundwater feature in the associated Hydrogeology Index map. Descriptive topics are grouped into the following themes: Location and administration; Demographics; Physical geography; Surface water; Geology; Hydrogeology; Groundwater; Groundwater management and use; Environment; Land use and industry types; and Scientific stimulus. This Galilee Basin dataset contains descriptive attribute information for the areas bounded by the relevant spatial groundwater feature in the associated Hydrogeology Index map. Descriptive topics are grouped into the following themes: Location and administration; Demographics; Physical geography; Surface water; Geology; Hydrogeology; Groundwater; Groundwater management and use; Environment; Land use and industry types; and Scientific stimulus. The Galilee Basin is a large intracratonic sedimentary basin in central Queensland. The basin contains a variably thick sequence of Late Carboniferous to Middle Triassic clastic sedimentary rocks dominated by laterally extensive sandstone, mudstone and coal. These rocks were mostly deposited in non-marine environments (rivers, swamps and lakes), although there is minor evidence for marginal marine settings such as deltas and estuaries. Sedimentation did not occur continuously across the approximately 90 million year history of basin development, and intervals of episodic compression, uplift and erosion were marked by distinct depositional breaks. Over much of the surface area of the Galilee Basin the main aquifers targeted for groundwater extraction occur in the younger rocks and sediments that overlie the deeper sequence of the Galilee Basin. The primary aquifers that supply groundwater in this region are those of the Eromanga Basin, as well as more localised deposits of Cenozoic alluvium. However, in the central-east and north-east of the Galilee Basin, the Carboniferous to Triassic rocks occur at or close to surface and several aquifer units supply significant volumes of groundwater to support pastoral and town water supplies, as well as being the water source for several spring complexes. The three main groundwater systems identified in the Galilee Basin occur in the 1. Clematis Group aquifer, 2. partial aquifer of the upper Permian coal measures (including the Betts Creek beds and Colinlea Sandstone), and 3. aquifers of the basal Joe Joe Group. The main hydrogeological units that confine regional groundwater flow in the Galilee Basin are (from upper- to lower-most) the Moolayember Formation, Rewan Formation, Jochmus Formation and Jericho Formation. However, some bores may tap local groundwater resources within these regional aquitards in areas where they outcrop or occur close to surface. Such areas of localised partial aquifer potential may be due in part to enhanced groundwater storage due to weathering and fracturing.

  • Borehole induction conductivity (IC) and gamma logging are geophysical techniques that provide bulk electrical conductivity and natural gamma trends of geological formations. The measured unit of IC is millisiemens per metre, whereas natural gamma is either counts per second or American Petroleum Index (API). The data were acquired as part of the Exploring for the Future program at field sites within the East Kimberley area in Western Australia, and the northern and southern Stuart Corridor projects in the Northern Territory. Data may be downloaded as Log ASCII Standard (LAS) format files or viewed through the Geoscience Australia Portal, or accessed via Geoscience Australia’s WMS and WFS web services.

  • Mafic igneous rocks are thought to be an important source of metals for the ca. 1640–1595 Ma sediment-hosted base metal deposits in the Paleo- to Mesoproterozoic Mount Isa – McArthur Basin system of northern Australia. Such rocks are widespread—the voluminous rift-related mafic magmatism at ca. 1790–1775 Ma and ca. 1730–1710 Ma—and show local evidence for intense hydrothermal alteration and metal leaching. To better constrain the nature, degree, and regional and temporal extent of alteration and metal leaching in these rocks, we have undertaken regional sampling of mafic igneous units from available drillcore, for geochemistry, stable isotopes and petrological examination. Sampling focused on magmatism of both ages in the southeastern MacArthur Basin, complementing the extensive pre-existing data for the Mount Isa region. Alteration in the mafic igneous rocks of the southeastern McArthur Basin ranges from mildly to strongly chloritic in the older units to strongly potassic (K-feldspar–chlorite–hematite) in the younger units. The latter alteration is ubiquitous, well developed and characterised by strong K2O enrichment and extreme depletion in CaO and Na2O. Geochemical data show that this intense and pervasive potassic alteration extends to similar-aged mafic rocks in the western Mount Isa region. Metal leaching is present in both alteration types, with strong Cu and Pb depletion in the most chlorite-altered rocks, and Zn and Cu depletion in the potassic alteration. Our oxygen isotope data for these mafic rocks (of both ages) in the southeastern McArthur Basin show a limited range of values (δ18O of 6–10‰) that are negatively correlated with K2O content. Our values are significantly lighter than published data for similar igneous rocks to the west, and indicate either a temperature zonation (ca. 250 °C in the east versus ca. 100 °C in the west; preferred) and/or different fluids. Results from our geochemical forward modelling indicate the requirement for exogenous K2O to produce the observed potassic alteration. The most likely source of this K was saline brines, consistent with the interpreted lacustrine and/or evaporitic environments for much of the McArthur Basin. Timing of alteration is uncertain, and the alteration may have included diagenetic low-temperature local K-rich brines and younger higher-temperature deep basinal brines. The temporal and geographically restricted nature of the potassic alteration, however, suggests restriction of K-rich, bittern evaporitic brine production in the younger and inboard parts of the Mount Isa – McArthur Basin system. Our results provide insights that directly relate to the genesis and exploration of basin-hosted Zn-Pb and Cu-Co mineral systems. They confirm that mafic igneous rocks in the region have lost significant amounts of both Zn and Cu, many times more than required for known deposits. The study also shows that metal leaching was accompanied by magnetite-destructive alteration. Hence, identifying zones of metal leaching may be possible using inversions of geophysical data, which may assist in targeting exploration. <b>Citation:</b> Champion, D.C., Huston, D.L., Bastrakov, E., Siegel, C., Thorne, J., Gibson, G.M. and Hauser, J., 2020. Alteration of mafic igneous rocks of the southern McArthur Basin: comparison with the Mount Isa region and implications for basin-hosted base metal deposits. 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.

  • To test existing geological interpretations and the regional stratigraphic relationships of the Carrara Sub-basin with adjacent resource-rich provinces, the deep stratigraphic drill hole NDI Carrara 1 was located on the western flanks of the Carrara Sub-basin, on the seismic line 17GA-SN1. The recovery of high quality near-continuous core from the Carrara Sub-basin, in concert with the spectrum of baseline analytical work being conducted by Geoscience Australia through the EFTF program, as well as other work by government and university researchers is greatly improving our understanding of this new basin. While recently published geochemistry baseline datasets have provided valuable insight into the Carrara Sub-basin, the age of the sedimentary rocks intersected by NDI Carrara 1 and their chronostratigraphic relationships with adjacent resource rich regions has remained an outstanding question. In this contribution, we present new sensitive high-resolution ion microprobe (SHRIMP) geochronology results from NDI Carrara 1 and establish regional stratigraphic correlations to better understand the energy and base-metal resource potential of this exciting frontier basin in northern Australia.