A review of mineral exploration trends, activities and discoveries in Australia in 2021.

Drilling in the Geoscience Australia Exploring for the Future East Tennant project was conducted as part of the MinEx CRC National Drilling Initiative. Ten stratigraphic boreholes were drilled for scientific purposes in the region around the Barkly Roadhouse in the Northern Territory. Where possible, the boreholes were comprehensively wireline logged to obtain petrophysical data on the cover and basement rocks to help improve knowledge and geophysical models of the region. Formation density data obtained by wireline logging were validated using laboratory-based bulk density data obtained by Archimedes method on diamond drill core samples at Geoscience Australia. Results of the validation show that wireline-logged formation density data and Archimedes wet bulk density data are in good general agreement in the first five boreholes drilled (NDIBK01, NDIBK02, NDIBK03, NDIBK04 and NDIBK05). Difficult drilling and some lost drilling equipment meant that boreholes NDIBK06, NDIBK07 and NDIBK09 could not be cased properly, or could not be re-entered, and thus formation density wireline logs could not be obtained in these holes. Boreholes NDIBK08 and NDIBK10 were wireline logged, however formation density results from these last two holes were problematic. Wireline formation density results for borehole NDIBK08 are shown to be too high due to miscalibration of the wireline formation density tool, and results from borehole NDIBK10 cannot be robustly assessed because of a lack of sufficient Archimedes bulk density data needed to provide statistical relevance and validate the wireline formation density data.

This Record presents 40Ar/39Ar chronologic results acquired in support of collaborative regional geoscientific investigations and mapping programs conducted by Geoscience Australia (GA) and the Northern Territory Geological Survey (NTGS). Argon isotopic data and interpretations from hornblende, muscovite, and biotite from seven samples collected from the Aileron Province in ALCOOTA , HUCKITTA, HALE RIVER, and ILLOGWA CREEK in the Northern Territory are presented herein. The results complement pre-existing geochronological constraints from U–Pb zircon and monazite analyses of the same or related samples, and provide new constraints on the thermal and deformation history of the Aileron Province. Three samples (2003082017, 2003082021, 2003083040) were taken from ALCOOTA in the northeastern portion of the Aileron Province. Biotite in sample 2003082017 from the ca 1.81 Ga Crooked Hole Granite records cooling below 320–280°C at 441 ± 5 Ma. Biotite in sample 2003082021 from the ca 1.73 Ga Jamaica Granite records cooling below 320–280°C at or after 414 ± 2 Ma. Muscovite in sample 2003083040 from the Delny Metamorphics, which were deposited after ca 1.82 Ga and preserve evidence for metamorphism at ca 1.72 Ga and 1.69 Ga, records cooling below 430–390°C at 399 ± 2 Ma. The fabrics preserved in the samples from the Crooked Hole Granite and Delny Metamorphics are interpreted to have formed due to dynamic metamorphism related to movement on the Waite River Shear Zone, an extension of the Delny Shear Zone, during the Palaeoproterozoic. Portions of the northeastern Aileron Province are unconformably overlain by the Neoproterozoic–Cambrian Georgina Basin, indicating these samples were likely at or near the surface by the Neoproterozoic. Together, these data indicate that rocks of the Aileron Province in ALCOOTA were subjected to heating above ~400°C during the Palaeozoic. Two samples (2003087859K, 2003087862F) of exoskarn from an indeterminate unit were taken from drillhole MDDH4 in the Molyhil tungsten–molybdenum deposit in central HUCKITTA. The rocks hosting the Molyhil tungsten–molybdenum deposit are interpreted as ca 1.79 Ga Deep Bore Metamorphics and ca 1.80 Ga Yam Gneiss. They experienced long-lived metamorphism during the Palaeoproterozoic, with supersolidus metamorphism observed until at least ca 1.72 Ga. Hornblende from sample 2003087859K indicates cooling below 520–480°C by 1702 ± 5 Ma and may closely approximate timing of skarn-related mineralisation at the Molyhil deposit; hornblende from sample 2003087862F records a phase of fluid flow at the Molyhil deposit at 1660 ± 4 Ma. The Salthole Gneiss has a granitic protolith that was emplaced at ca 1.79 Ga, and experienced alteration at ca 1.77 Ga. Muscovite from sample 2010080001 of Salthole Gneiss from the Illogwa Shear Zone in ILLOGWA CREEK records cooling of the sample below ~430–390°C at 327 ± 2 Ma. This may reflect the timing of movement of, or fluid flux along, the Illogwa Shear Zone. An unnamed quartzite in the Casey Inlier in HALE RIVER has a zircon U–Pb maximum depositional age of ca 1.24 Ga. Muscovite from sample HA05IRS071 of this unnamed quartzite yields an age of 1072 ± 8 Ma, which likely approximates, or closely post-dates, the timing of deformation in this sample; it provides the first direct evidence for a Mesoproterozoic episode of deformation in this part of the Aileron Province.

Barnicarndy 1 is a stratigraphic well drilled in the southern part of the Canning Basin’s Barnicarndy Graben under Geoscience Australia’s Exploring for the Future program in collaboration with the Geological Survey of Western Australia to provide stratigraphic data for this poorly understood tectonic component. The well intersects a thin Cenozoic section, Permian–Carboniferous fluvial clastics and glacial diamictites and a thick pre-Carboniferous succession (855–2585 mRT) unconformably overlying Neoproterozoic metasedimentary rocks. Three informal siliciclastic intervals were defined based on core lithology, well logs, chemical and mineral compositions: the Upper Sandstone (855–1348.1 mRT), Middle Interval (1348.1–2443.4 mRT) and Lower Sandstone (2443.4–2585 mRT). The Middle Interval was further divided into six internal zones. Both conventional methods and artificial neural network technology were applied to well logs to interpret petrophysical and elastic properties, total organic carbon (TOC) content, pyrolysis products from the cracking of organic matter (S2) and mineral compositions. Average sandstone porosity and reservoir permeability are 17.9% and 464.5 mD in the Upper Sandstone and 6.75% and 10 mD in the Lower Sandstone. The Middle Interval claystone has an average porosity and permeability of 4.17% and 0.006 mD, and average TOC content and S2 value of 0.17 wt% and 0.047 mg HC/g rock, with maximum values of 0.66 wt% and 0.46 mg HC/g rock, respectively. Correlations of mineral compositions and petrophysical, geomechanical and organic geochemical properties of the Middle Interval have been conducted and demonstrate that these sediments are organically lean and lie within the oil and gas window. Published in The APPEA Journal 2021 <b>Citation:</b> Wang Liuqi, Edwards Dianne S., Bailey Adam, Carr Lidena K., Boreham Chris J., Grosjean Emmanuelle, Normore Leon, Anderson Jade, Jarrett Amber J. M., MacFarlane Susannah, Southby Chris, Carson Chris, Khider Kamal, Henson Paul, Haines Peter, Walker Mike (2021) Petrophysical and geochemical interpretations of well logs from the pre-Carboniferous succession in Barnicarndy 1, Canning Basin, Western Australia. <i>The APPEA Journal</i><b> 61</b>, 253-270. https://doi.org/10.1071/AJ20038

This Central Australian Fractured Rock Province 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 Mesoproterozoic Musgrave Province is a significant geological feature in Central Australia, covering around 130,000 square kilometres across the tri-border region of Northern Territory, South Australia, and eastern Western Australia. It is characterized by east-west trending, metamorphosed igneous rocks, including granites, intrusions, and volcanics. The province experienced various deformation events, including the Mount West Orogeny and Musgravian Orogeny, resulting in the emplacement of granites and high-grade metamorphism. The Ngaanyatjarra Rift (1090 to 1040 Ma) is a failed intracontinental rift that formed due to magmatism-induced extension. The associated Giles Event was characterised by mafic to ultra-mafic intrusions (Giles Suite), bimodal volcanism and rift sedimentation (Bentley Supergroup), granitic intrusions and dyke emplacement. The Giles Event was followed by the emplacement of dolerite dykes including the Kullal Dyke Suite and the Amata Dolerite, approximately 1000 Ma and 825 Ma. The Peterman Orogeny played a crucial role in shaping the geological architecture of the Musgrave Province, forming the distinctive east-to-west-directed ranges.

This Maryborough-Nambour 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 Maryborough Basin is a half-graben intracratonic sag basin mainly filled with Early Cretaceous rocks, overlain by up to 100 m of Cenozoic sediments. It adjoins the older Nambour Basin to the south, comprising Triassic to Jurassic rocks. The boundary between the basins has shifted due to changes in sedimentary unit classifications, with the Cretaceous units now restricted to the Maryborough Basin and Jurassic and older units assigned to the Nambour Basin. Both basins are bounded to the west and unconformably overlies older Permian and Triassic rocks in the Gympie Province and Wandilla Province of the New England Orogen. In the south of the Nambour Basin, it partly overlaps with the Triassic Ipswich Basin. The Nambour Basin in the south is primarily composed of the Nambour Formation, with interbedded conglomerate, sandstone, siltstone, shale, and minor coal. Overlying this is the Landsborough Sandstone, a unit with continental, fluviatile sediments and a thickness of up to 450 m. In the north, the Duckinwilla Group contains the Myrtle Creek Sandstone and the Tiaro Coal Measures, which were formerly considered part of the Maryborough Basin but are now associated with the northern Nambour Basin. In contrast, the Maryborough Basin consists of three main Cretaceous units and an upper Cenozoic unit. The Grahams Creek Formation is the deepest, featuring terrestrial volcanic rocks, volcaniclastic sedimentary rocks, and minor pyroclastic rocks. The overlying Maryborough Formation was deposited in a continental environment with subsequent marine incursion and includes mudstone, siltstone, minor sandstone, limestone, conglomerate, and tuff. The upper Cretaceous unit is the Burrum Coal Measures, comprising interbedded sedimentary rocks deposited in fluvial to deltaic environments. The uppermost unit, the Eocene to Miocene Elliott Formation, includes sandstone, siltstone, conglomerate, and shale deposited in fluvial to deltaic environments. Cenozoic sediments overlying the Elliott Formation consist of Quaternary alluvium, coastal deposits, and sand islands like Fraser Island, influenced by eustatic sea level variations. Volcanic deposits and freshwater sediments also occur in some areas. Adjacent basins, such as the Clarence-Moreton Basin and Capricorn Basin, have stratigraphic correlations with the Maryborough Basin. The Oxley Basin lies to the south, overlying the Ipswich Basin. In summary, the Maryborough Basin and the older Nambour Basin exhibit distinct geological characteristics, with varying rock formations, ages, and sedimentary features, contributing to the diverse landscape of the region.

Under the Federal Governments’ Exploring for the Future (EFTF) program, Geoscience Australia (GA) recently acquired the Barkly and South Nicholson deep-crustal seismic reflection surveys (L212 and L210, respectively) in partnership with the Northern Territory Geological Survey (NTGS) and Geological Survey of Queensland (GSQ). The Barkly survey was completed in late 2019 as a collaboration between GA’s EFTF program and NTGS’s Resourcing the Territory initiative. Acquisition started at the Queensland-Northern Territory border near the town of Camooweal. It is comprised of five lines; 19GA-B1 (434.6 km), 19GA-B2 (45.9 km), 19GA-B3 (66.9 km), 19GA-B4 (225.8 km), and 19GA-B5 (39.4 km) (Southby et al., 2021), and was acquired via vibroseis using a nodal geophone system (Fomin et al., 2020), and links into the South Nicholson survey acquired in 2017. In 2019, the Camooweal deep-crustal seismic reflection survey (GSQ Open Data Portal 95590) was acquired by the GSQ as part of the Queensland Government's Strategic Resources Exploration Program (SREP), and was centred on the northwest Queensland town of Camooweal with the total length of acquisition spread over three lines; 19Q-C1 (65.8 km), 19Q-C2 (173.6 km) and 19Q-C3 (60.9 km). The Camooweal survey was acquired via vibroseis using a nodal geophone system and links to the South Nicholson and Barkly surveys (Edwards, 2020). These seismic surveys have improved our understanding of the basins, basement structures and structural evolution of the region. They tie the underexplored region with the more explored and highly prospective McArthur and Mount Isa Province, in which there are now new areas identified for future exploration. The known, mappable extent of the South Nicholson Basin has been increased significantly and a new, potentially Proterozoic age, depocentre, the Carrara Sub-basin, located in the south east of South Nicholson region, has been discovered (Henson et al., 2018; Carr et al., 2019; Carson et al., 2020; MacFarlane et al., 2020). The Carrara Sub-basin is interpreted to include strata equivalent in age to the Isa Superbasin, South Nicholson Group, and the Georgina Basin (Carr et al., 2020) and current work on the NDI Carrara 1 drill hole will further constrain the stratigraphy and geology of the South Nicholson region; providing well control to the extensive network of new deep-crustal seismic acquired in this highly prospective frontier province. The aim of this study is to show the extent of the Carrara Sub-basin sedimentary packages by mapping the lateral extent of sedimentary sequences using seismic data interpretation. This Abstract was submitted/presented to the 2022 Central Australian Basins Symposium IV (CABS) 29-30 August (https://agentur.eventsair.com/cabsiv/)

Geoscience Australia’s Exploring for the Future (EFTF) program provides precompetitive information 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 leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia’s transition to a low emissions economy, strong resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government. The deep stratigraphic drill hole, NDI Carrara 1 (~1751 m), was completed in December 2020 as part of the MinEx CRC National Drilling Initiative (NDI) in collaboration with Geoscience Australia and the Northern Territory Geological Survey. It is the first test of the Carrara Sub-basin, a depocentre newly discovered in the South Nicholson region based on interpretation from seismic surveys (L210 in 2017 and L212 in 2019) recently acquired as part of the Exploring for the Future program. The drill hole intersected approximately 1100 m of Proterozoic sedimentary rocks uncomformably overlain by 630 m of Cambrian Georgina Basin carbonates. This contractor report (FIT - Schlumberger) presents hydrocarbon and aqueous fluid inclusion petrology and data (micro-thermometry, salinities etc.) on four hydrocarbon-bearing calcite veins sampled from NDI Carrara 1 between 762.56-763.60 m depth, (under contract to, and fully funded by, Geoscience Australia as part of the Exploring for the Future program).

The importance of critical minerals and the need to expand and diversify critical mineral supply chains has been endorsed by the Federal governments of Australia, Canada, and the United States. The geoscience organizations of Geoscience Australia, the Geological Survey of Canada and the U.S. Geological Survey have created the Critical Minerals Mapping Initiative to build a diversified critical minerals industry in Australia, Canada, and the United States by developing a better understanding of known critical mineral resources, determining geologic controls on critical mineral distribution for deposits currently producing byproducts, identifying new sources of supply through critical mineral potential mapping and quantitative mineral assessments, and promoting critical mineral discovery in all three countries.

The Geoscience Australia Structural Measurements Database contains field measurements of geological structure features such as bedding, foliation, lineation, faults and folds from field sites, measured sections, and boreholes. The database is delivered as a layer in Geoscience Australia's "Geological Field Sites, Samples and Observations" web service.