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.

Geoscience Australia, in collaboration with Mineral Resources Tasmania, will be carrying out an airborne magnetic and radiometric survey in eastern Tasmania during 2022. The survey is part of the Australian Government’s Exploring for the Future program, which is committed to supporting a strong economy, resilient society and sustainable environment for the benefit of Australians. At its heart, the program is about contributing to a sustainable, long-term future for Australia through an improved understanding of the nation’s mineral, energy and groundwater resource potential. <p>

Geoscience Australia, in collaboration with state governments, will be carrying out airborne electromagnetic (AEM) surveys in eastern South Australia and western NSW and Victoria during 2022. The Australian Government’s Exploring for the Future program, led by Geoscience Australia, is committed to supporting a strong economy, resilient society and sustainable environment for the benefit of Australians. At its heart, the program is about contributing to a sustainable, long-term future for Australia through an improved understanding of the nation’s mineral, energy and groundwater resource potential <p>

As global metal demands are increasing whilst new discoveries are declining, the magnetotelluric (MT) technique has shown promise as an effective technique to aid mineral systems mapping. Several case studies have shown a spatial correlation between mineral deposits and conductors, with some showing that resistivity models derived from MT are capable of mapping mineral systems from the lithosphere to deposit scale. However, until now, the statistical significance of such correlations has not been demonstrated and therefore hindered robust utilization of MT data in mineral potential assessments. Here we quantitatively analyze resistivity models from Australia, the United States of America (USA), South America and China and demonstrate that there is a statistically-significant correlation between upper mantle conductors and porphyry copper deposits, and between mid-crustal conductors and orogenic gold deposits. Volcanic hosted massive sulfide deposits show significant correlation with upper mantle conductors in Australia. Differences in the correlation pattern between these deposit types likely relate to differences in the chemistry, redox state and location of source mineralizing fluids and magmas, and indicate signatures of mineral system processes can be preserved in the crust and mantle lithosphere for hundreds of millions of years. Appeared in Scientific Reports volume 12, Article number: 8190 (2022), 17 May 2022

The Ordovician to Cretaceous Canning Basin of Western Australia is an underexplored prospective onshore petroleum basin with proven petroleum systems currently producing on a small-scale. The Canning Basin has recently become a site of interest for unconventional hydrocarbon exploration, with several formations within deeper basin depocentres being investigated for resources and estimates that suggest it may have the largest shale gas potential in Australia. Modern petroleum resource evaluation generally depends on an understanding of both local and regional stresses, which are a primary control over the formation and propagation of induced fractures. Presently, there are significant gaps in our understanding of these factors within the Canning Basin. This study characterises the regional stress regime of the onshore Canning Basin and presents detailed models of present-day stress within the subsurface. These allow for the identification of significant stress heterogeneities and natural barriers to fracture propagation. Wireline data interpretation reveals a variable present-day state of stress in the Canning Basin. An approximately NE-SW regional present-day maximum horizontal stress orientation is interpreted from observed wellbore failure in image logs, in broad agreement with both the Australian Stress Map and previously published earthquake focal mechanism data. One-dimensional mechanical earth models constructed for intervals from 15 Canning Basin petroleum wells highlight the relationship between lithology and stress. This study describes significant changes in stress within and between lithological units due to the existence of discrete mechanical units, forming numerous inter- and intra- formational stress boundaries likely to act as natural barriers to fracture propagation, particularly within units currently targeted for their unconventional resource potential. Broadly, a strike-slip faulting stress regime is interpreted through the basin, however, when analysed in detail there are three distinct stress zones identified.: 1) a transitional reverse- to strike-slip faulting stress regime in the top ~1 km of the basin, 2) a strike-slip faulting stress regime from ~1 km to ~3.0 km depth, and 3) a transitional strike-slip to normal faulting regime at depths greater than ~3.0 km. This study is a component of the Australian Government’s Exploring for the Future (EFTF) initiative, which is focused on gathering new data and information about the resource potential concealed beneath the surface across northern Australia. Appeared online in the Australian Journal of Earth Sciences 17 Feb 2021

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.

This data release contains accurate positional data for groundwater boreholes in terms of horizontal location as well as elevation of the top of casing protectors. Twenty-four boreholes located in the Nulla and McBride basalt provinces have had DGPS survey results compiled and are presented. Using 95% confidence intervals, the horizontal uncertainties are less than 1.2m and vertical uncertainties less than 0.9m. These results are a substantial improvement, particularly on the uncertainty of elevations, and as such allow water levels need to be compared between bores on a comparable datum, to enable a regional hydrogeological understanding. Quantifying the uncertainties in elevation data adds robustness to the analysis of water levels across the region rather than detracting from it.

The Exploring for the Future Program (EFTF) is a $100.5 million four year, federally funded initiative to better characterise the mineral, energy and groundwater potential of northern Australia. A key focus area of the initiative is the South Nicholson region, situated across the Northern Territory and Queensland border. The South Nicholson region is located between two highly prospective provinces, the greater McArthur Basin in the Northern Territory, the Lawn Hill Platform and the Mount Isa Province in Queensland–Northern Territory, which both have demonstrated hydrocarbon and base metal resources. In contrast, the South Nicholson region is not well understood geologically, is mostly undercover with limited well data, and prior to EFTF contained limited seismic coverage. Re–Os analyses in this study were undertaken to complement seismic data, U–Pb geochronology and geochemistry data to better understand the geological evolution and resource potential of the South Nicholson region. Five organic carbon bearing sedimentary samples from drillholes BMR Ranken 1, NTGS00/1, DDH 83/1 and DDH 83/4 located across the South Nicholson region were analysed for whole rock Re–Os. The aim of the analyses was to better constrain the depositional age of basin units in the region, and to potentially provide insights into the timing of post-depositional processes such as fluid events and hydrocarbon generation and/or migration. Samples belong to the Mesoproterozoic South Nicholson Group, Paleoproterozoic Fickling and McNamara groups, and the Neoproterozoic to Devonian Georgina Basin. Samples were analysed at the University of Alberta, Canada.

Constraints on the morphology of the Moho are essential to establish reliable models of the subsurface and infer the evolution of the Australian crust. Reliable information on crustal thickness variations is important for thermal modelling and structural mapping, for both energy and mineral system studies. Here, we combine information from both passive seismic deployments and full-crustal reflection seismic profiling to produce a new representation of the character of the Moho in northern Australia. Data coverage has been dramatically improved by investments, under the Exploring for the Future program, in new deployments of passive seismic instrumentation and expansion of the network of reflection seismic profiles in the South Nicholson and Barkly regions. Using a new approach to combining results from different classes of seismic analysis, different spatial sampling associated with the various types of data have been taken into account. The resulting Moho surface reveals small-scale features not seen in previous models. New data reveal that some Moho discontinuities are clearly associated with known structures such as the Willowra Suture. Similar ~100 km wavelength undulations are visible in areas under cover that may indicate the presence of unknown major structures. Significant base metal mineral deposits appear to be localised along the edges of thicker crustal block. <b>Citation:</b> Gorbatov, A., Medlin, A., Kennett, B.L.N., Doublier, M.P., Czarnota, K., Fomin, T. and Henson, P., 2020. Moho variations in northern Australia. 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.

Remotely sensed data and updated DEM and radiometric datasets, combined with existing surface material and landform mapping were used to map regolith landform units for the Ti Tree, Western Davenport and Tennant Creek regions of the SSC project. This report describes the methods used and outlines the new mapping.