<p>The Mesoproterozoic Roper Group of the McArthur Basin has excellent petroleum potential, but its poorly constrained post-depositional history has hampered resource exploration and management. The Derim Derim Dolerite occupies an important position in the regional event chronology, having intruded the Roper Group prior to deformation associated with the ‘Post-Roper Inversion’ event. It was assigned a magmatic crystallisation age of 1324 ± 4 Ma (uncertainties are 95% confidence unless otherwise indicated) in 1997, based on unpublished Sensitive High Resolution Ion Micro Probe (SHRIMP) U-Pb analyses of dolerite-hosted baddeleyite from sample 97106010, collected from the Derim Derim Dolerite type locality in outcrop within the northwestern McArthur Basin. Herein, we refine these data via Isotope Dilution-Thermal Ionisation Mass Spectrometry (ID-TIMS) analysis of baddeleyites plucked from the SHRIMP grain-mounts, which yielded a precise mean 207Pb/206Pb date of 1327.5 ± 0.6 Ma. This date is significantly older than a baddeleyite U-Pb ID-TIMS date of 1313.8 ± 1.3 Ma recently obtained from dolerite ALT-05, sampled in Pacific Oil and Gas Ltd drillhole Altree 2, near the northern margin of the Beetaloo Sub-basin, and 200 km south of 97106010. This pair of results indicates that Derim Derim Dolerite magmatism spanned at least 10-15 Ma. Previously documented geochemical variation in Mesoproterozoic mafic rocks across the Northern Territory (such as the 1325 ± 36 Ma (2σ) Galiwinku Dolerite in the northern McArthur Basin, 1316 ± 40 Ma phonolites intruding the eastern Pine Creek Orogen, and 1295 ± 14 Ma gabbro in the Tomkinson Province) may reflect episodic pulses of magmatism hitherto obscured by the low precision of the available isotopic dates. <p><b>Citation:</b> Bodorkos, S., Yang, B., Collins, A.S., Crowley, J., Denyszyn, S.W., Claoue-Long, J.C., Anderson, J.R. and Magee, C., 2020 Precise U–Pb baddeleyite dating of the Derim Derim Dolerite: evidence for episodic mafic magmatism in the greater McArthur Basin. 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.

For more than half a century, seismic tomography has been used to map the volumetric structure of Earth’s interior, but only recent advances in computation have enabled the application of this technique at scale. Estimates of surface waves that travel between two seismic stations can be reconstructed from a stack of cross-correlations of continuous data recorded by seismometers. Here, we use data from the Exploring for the Future program AusArray deployment to extract this ambient noise signal of Rayleigh waves and use it to image mid- to upper-crustal structure between Tennant Creek and Mount Isa. Our aim was to establish a repeatable, semi-automatic workflow that can be extended to the entire Australian continent and beyond. Shear wave velocity models at 4, 6, 8 and 10 s periods are presented. A strong low-velocity anomaly (2.5 km/s) at a period of 4 s (~2–4 km depth) delineates the outline of the newly discovered, and prospective for hydrocarbons, Carrara Sub-basin. A near-vertical high-velocity anomaly (3.5 km/s) north of Mount Isa extends from the near surface down to ~12 km and merges with northeast-trending anomalies. These elongate features are likely to reflect compositional variations within the mid-crust associated with major structures inferred to be associated with base metal deposits. These outcomes demonstrate the utility of the ambient noise tomography method of imaging first-order features, which feed into resource potential assessments. <b>Citation: </b>Hejrani, B., Hassan, R., Gorbatov, A., Sambridge, M. Hawkins, R., Valentine, A., Czarnota, K. and Zhao, J., 2020. Ambient noise tomography of Australia: application to AusArray deployment. 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. <b>See eCat record <a href="https://dx.doi.org/10.26186/148676">#148676</a> for the updated version of the model package.</b>

Metamorphic rocks provide a semi-continuous record of the thermal and barometric history of the crust, which is particularly useful in constraining paleo-crustal architectures, tectonic models and thereby mineral exploration. Given this importance, regional metamorphic studies in Australia have flourished during the past 30 years. However, the national metamorphic map of Australia has not been updated in more than 37 years. Here, we provide a snapshot of a national synthesis of all available quantitative metamorphic data, metamorphic chronology and metamorphic map patterns, integrated with stratigraphic, magmatic and kinematic datasets. Forty-eight orogenic cycles have been identified, spanning from the Paleoarchean to the Miocene, and most of permissible pressure (P) and temperature (T) space, indicating a wide variety of tectonic settings. This compilation provides a basis for establishing best-estimate working models for the metamorphic evolution of all orogenic systems, provinces and terranes. These insights are important in advancing the understanding of mineral systems in Australia.. <b>Citation:</b> Goscombe, B., Czarnota, K. Blewett, R.S. Skirrow, R.G. Everard, J.L. and Lawson, C., 2020. Metamorphic evolution of 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.

The Exploring for the Future program Virtual Roadshow was held on 7 July and 14-17 July 2020. The Minerals session of the roadshow was held on 14 July 2020 and consisted of the following presentations: Introduction - Richard Blewett Preamble - Karol Kzarnota Surface & Basins or Cover - Marie-Aude Bonnardot Crust - Kathryn Waltenberg Mantle - Marcus Haynes Zinc on the edge: New insights into sediment-hosted base metals mineral system - David Huston Scale reduction targeting for Iron-Oxide-Copper-Gold in Tennant Creek and Mt Isa - Anthony Schofield and Andrew Clark Economic Fairways and Wrap-up - Karol Czarnota

The Houtman Sub-basin geophysical modelling study is an integrated geological and geophysical interpretation of the GA-349 seismic survey. The key aims for the study were to improve the understanding of the crustal architecture of the Houtman Sub-basin and the distribution and thickness of magmatic rocks. The Houtman Sub-basin is a largely unexplored offshore depocentre in the northern Perth Basin on the western margin of Australia. It formed during two separate rifting episodes (Early- to Mid-Permian, Early Jurassic to Early Cretaceous) and may contain up to 19 km of sediment. The northern Houtman Sub-basin contains extensive breakup-related sill and dyke complexes, related to both the adjacent volcanic province of the Wallaby Plateau and the Wallaby Zenith Transform Margin (WZTM). New 2D seismic reflection data obtained in 2014/15 (GA-349) is being used to re-assess the petroleum prospectivity of this frontier basin to underpin the possible future release of exploration acreage. A full understanding of petroleum prospectivity requires a clear picture of sediment thickness, the nature of basement, and the distribution of magmatic rocks, all of which influence the maturation of hydrocarbons and ultimately prospectivity. Geoscience Australia seismic survey (GA-310) and marine sampling survey (GA-2476) conducted in 2008 and 2009 acquired a total of about 26,000 km of new gravity and magnetic data. This new gravity and magnetic data has been integrated and levelled with existing data, both offshore and onshore, to produce unified gravity and magnetic datasets for use in constraining regional tectonics, basin structure and petroleum prospectivity. The purpose of this study is to use potential field modelling to: a) validate seismic interpretation of crustal structure (in depth), including Moho depth and depth to top crystalline basement; b) model density variations within the sedimentary section; c) model density and magnetic susceptibility variations within basement with an interpretation of basement composition (if possible) and; d) investigate the depth, extent and thickness of intrabasinal magmatic rocks identified on seismic data.

<div><strong>Output Type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short Abstract: </strong>The continental crust directly hosts or underlies almost all mineral resources on which society depends. Despite its obvious importance its structure is poorly characterised. In particular, its density is surprisingly poorly constrained because it is difficult to directly image from the surface. Here we collate a global database of crustal thickness and velocity constraints. In combination with a compilation of published laboratory experimental constraints on seismic velocity at a range of pressures, we develop a scheme with which to convert seismic velocities into density as a function of pressure and temperature. We apply this approach to the Australian crystalline basement. We find that the Australian crust is highly heterogeneous, ranging in bulk density from 2.7—3.0 g cm-3. Finally, we explore the utility of our database for testing hypotheses about the location and endowment of mineral resources using porphyry copper deposits as an example. Our results provide an improved framework with which to explore the subsidence and thermal evolution of sedimentary basins, as well as probing relationships between deposit types and crustal architecture.</div><div><br></div><div><strong>Citation: </strong>Stephenson, S.N., Hoggard, M.J., Haynes, M.W., Czarnota, K. & Hejrani, B., 2024. Constraints on continental crustal thickness and density structure. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://doi.org/10.26186/149336</div>

Crustal architecture places first-order controls on the distribution of mineral and energy resources. However, despite its importance, it is poorly constrained over much of northern Australia. Here, we present a full crustal interpretation of deep seismic reflection profile 18GA-KB1 that extends over 872 km from the Eo- to Mesoarchean Pilbara Craton to the Paleoproterozoic Aileron Province, transecting a range of stratigraphic and tectonic basement units, some of which are completely concealed by younger rocks. The seismic profile provides the first coherent image through this relatively poorly understood part of Australian geology and yields major new insights about the crustal architecture, geometry and definition of the different geological and seismic provinces and their boundaries. Key findings include the following: (1) The Pilbara Craton shows a three-component horizontal crustal layering, where the granite– greenstone East Pilbara Terrane is largely confined to the upper crust. (2) The Pilbara Craton has an extensive reworked margin, the Warrawagine Seismic Province, that thins towards the east, and underlies the western and central Rudall Province. (3) At the largest scale, the Rudall Province shows an approximately funnel-shaped geometry, with limited differences in seismic character between the various terranes. (4) The western Kidson Sub-basin is underlain by rocks of the Neoproterozoic Yeneena Basin and Rudall Province. (5) The central and eastern part of the Kidson Sub-basin rests on the coherent, relatively poorly structured Punmu Seismic Province, which is truncated by the steep, crustal-scale Lasseter Shear Zone, that marks the boundary to the Aileron Province to the east. <b>Citation:</b> Doublier, M.P., Johnson, S.P., Gessner, K., Howard, H., Chopping, R., Smithies, R.H., Martin, D.McB.,Kelsey, D.E., Haines, P.w., Hickman, A., Czarnota, K., Southby, C., Champion, D.C., Huston, D.L., Calvert, A.J., Kohanpour, F., Moro, P., Costelloe, R., Fomin, T. and Kennett, B.L.N., 2020. Basement architecture from the Pilbara Craton to the Aileron Province: new insights from deep seismic reflection line 18GA-KB1. 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.

Water, energy and mineral resources are vital for Australia’s economic prosperity and sustainable development. However, continued supply of these resources cannot be taken for granted. It is widely accepted that the frontier of exploration now lies beneath the Earth’s surface, making characterisation of the subsurface a unifying challenge. Between 2016 and 2020, the $100.5 million Exploring for the Future program focused on addressing this challenge across northern Australia in order to better define resource potential and boost investment. The program applied a multiscale systems approach to resource assessment based on characterisation of the Australian plate from the surface down to its base, underpinned by methodological advances. The unprecedented scale and diversity of new data collected have resulted in many world-first achievements and breakthrough insights through integrated systems science. Through this multi-agency effort, new continental-scale datasets are emerging to further enhance Australia’s world-leading coverage. The program has identified prospective regions for a wide range of resources and pioneered approaches to exploration undercover that can be applied elsewhere. The outcomes so far include extensive tenement uptake for minerals and energy exploration in covered terranes, and development of informed land-management policy. Here, we summarise the key scientific achievements of the program by reviewing the main themes and interrelationships of 62 contributions, which together constitute the Exploring for the Future: extended abstracts volume. <b>Citation:</b> Czarnota, K., Roach, I.C., Abbott, S.T., Haynes, M.W., Kositcin, N., Ray, A. and Slatter, E., 2020. Exploring for the Future: advancing the search for groundwater, energy and mineral resources. 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.

Geological maps are one of the most important datasets used in resource exploration and management. Despite increasing demand for subsurface resources such as minerals, groundwater and energy, maps of the inferred subsurface geology of Australia and other continents have been limited to small regions or jurisdictions. Here, we present the first seamless semi-continental chronostratigraphic solid geology dataset of the North Australian Craton. This dataset comprises five time slices of stratigraphic units: Cenozoic, Mesozoic, Paleozoic, Neoproterozoic and pre-Neoproterozoic. Interpretation of covered units is based on available data: surface geology and solid geology maps, magnetic intensity and gravity images, drilling logs, reflection seismic profiles and airborne electromagnetic soundings. In total, 2008 units have been mapped, all linked to the Australian Stratigraphic Units Database. So far, these maps have led to a refinement of sedimentary basin and tectonic province outlines, lessened the risks of mineral exploration through Australia’s extensive superficial cover, disclosed geological units known to host resources elsewhere, and highlighted undercover regions with poor geological constraints. <b>Citation:</b> Stewart, A.J., Liu, S.F., Bonnardot, M.-A., Highet, L.M., Woods, M., Brown, C., Czarnota, K. and Connors, K., 2020. Seamless chronostratigraphic solid geology of the North Australian Craton. 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.

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.