The NDI Carrara 1 sedimentology, microstructural analysis and sequence stratigraphy program was a joint undertaking between Geoscience Australia (GA) and CSIRO (Perth) as part of the Exploring for the Future program to examine the sedimentology, sequence stratigraphy and paleogeography of the Carrara Sub-basin. The program was based on recovered core from the National Drilling Initiative (NDI) deep stratigraphic drill hole, NDI Carrara 1. NDI Carrara 1 is the first drill hole to intersect the Proterozoic rocks of the Carrara Sub-Basin, a large depocentre discovered during seismic acquisition conducted during the first phase of the EFTF program in 2017. NDI Carrara 1 is located on the western flanks of the Carrara Sub-basin, reaching a total depth of 1751 m, intersecting ca. 630 m of Cambrian Georgina Basin overlying ca. 1100 m of Proterozoic carbonates, black shales and siliciclastics. This final report, and associated appendices, compiles the findings of three milestone deliverables. The first component of the report addresses the sedimentology of the Proterozoic section of NDI Carrara 1 with an accompanying Appendix (core log, from HyLogger data). The second component is a detailed microstructural analysis based on selected thin sections in intervals of interest. The final component completed a 1D sequence stratigraphic assessment, enabling regional stratigraphic correlations to be established and an interpretive paleogeographic map generated for the Proterozoic sequences of interest across the region .

Exploring for the future presentation- The structure and stratigraphy of the South Nicholson region – implications for resource prospectivity; Insight from the EFTF geochronology and deep reflection seismic programs

Zircon and xenotime U–Pb SHRIMP geochronology was conducted on samples from the South Nicholson Basin, and western Mount Isa Orogen. These samples were collected from outcrop and core from the Northern Territory and Queensland. The age data indicate the South Nicholson Basin was deposited after ca 1483 Ma but deposition most likely had ceased by ca 1266 Ma; the latter age likely represents post-diagenetic fluid flow in the area, based on U–Pb xenotime data. Geochronology presented here provides the first direct age data confirming the South Nicholson Group is broadly contemporaneous with the Roper Group of the McArthur Basin, which has identified facies with high hydrocarbon prospectivity. In addition, geochronology on the Paleoproterozoic McNamara Group provides new age constraints that have implications for the regional stratigraphy. The data obtained in this geochronological study allow for a comprehensive revision of the existing stratigraphic framework, new correlations and enhances commodity prospectivity in central northern Australia.

This petroleum systems summary report provides a compilation of the current understanding of petroleum systems for the South Nicholson Basin and Isa Superbasin region. The contents of this report are also available via the Geoscience Australia Portal at https://portal.ga.gov.au/, called The Petroleum Systems Summary Assessment Tool (Edwards et al., 2020). Three summaries have been developed as part of the Exploring for the Future (EFTF) program (Czarnota et al., 2020); the McArthur Basin, the Canning Basin, and a combined summary of the South Nicholson Basin and Isa Superbasin region. The petroleum systems summary reports aim to facilitate exploration by summarizing key datasets related to conventional and unconventional hydrocarbon exploration, enabling a quick, high-level assessment the hydrocarbon prospectivity of the region.

The Mesoproterozoic South Nicholson Basin sits between, and overlies, the Paleoproterozoic Mount Isa Province to the east and the southern McArthur Basin to the northwest. The McArthur Basin and Mount Isa Province are well studied and highly prospective for both mineral and energy resources. In contrast, rocks in the South Nicholson region (incorporating the Mount Isa Province, the Lawn Hill Platform and the South Nicholson Basin, and geographically straddling the Northern Territory and Queensland border) are mostly undercover, little studied and consequently relatively poorly understood. A comprehensive U-Pb sensitive high-resolution ion microprobe (SHRIMP) zircon and xenotime geochronology program was undertaken to better understand the stratigraphy of the South Nicholson region and its relationship to the adjacent, more overtly prospective Mount Isa Province and McArthur Basin. The age data indicate that South Nicholson Basin deposition commenced ca. 1483 Ma, with cessation at least by ca. 1266 Ma. The latter age, based on U-Pb xenotime, is interpreted as the timing of postdiagenetic regional fluid flow. The geochronology presented here provides the first direct age data confirming that the South Nicholson Group is broadly contemporaneous with the Roper Group of the McArthur Basin. Some rocks, mapped previously as Mesoproterozoic South Nicholson Group and comprising proximal, immature lithofacies, have detrital spectra consistent with that of the late Paleoproterozoic McNamara Group of the western Mount Isa Province; this will necessitate a revision of existing regional stratigraphic relationships. The stratigraphic revisions and correlations proposed here significantly expand the extent of highly prospective late Paleoproterozoic stratigraphy across the South Nicholson region, which, possibly, extends even further west beneath the Georgina and Carpentaria basins. Our data and conclusions allow improved regional stratigraphic correlations between Proterozoic basins, improved commodity prospectivity and targeted exploration strategies across northern Australia. <b>Citation:</b> Carson, C.J., Kositcin, N., Anderson, J.R., Cross, A. and Henson, P.A., 2020. New U–Pb geochronology for the South Nicholson region and implications for stratigraphic correlations.. 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 Buddycurrawa Volcanics (BV, Benmara Group) are a sequence of trachyte lavas and interleaved shallow-marine siliciclastic rocks, exposed in the Benmara region, northwestern Mount Drummond 1:250 000 map sheet, Northern Territory. Previous information, including resource potential, on the BV was limited, and stratigraphic correlation with other regional volcanic units was speculative. Our new geochronology data establish the extrusion age of the BV as late Paleoproterozoic, constrained by a maximum age of ca. 1662 Ma (SHRIMP U-Pb zircon) and a minimum age of ca 1631 Ma (in situ laser Rb-Sr on glauconite within vesicles). The BV are, therefore, temporally equivalent to numerous ash fall tuffs reported throughout regional highly prospective late Paleoproterozoic successions. The BV also host vertical siliceous pipes, representing ‘white smokers’—peripheral low-temperature equivalents of black smokers—suggestive of a regional shallow-marine hydrothermal circulatory system and potential for associated base metal mineral systems. The BV are pervasively potassically altered. Laser Rb-Sr dating on matrix secondary microcline returns ages ca. 1612–1323 Ma, reflecting timing of fluid flow responsible for at least some of the potassic alteration. These are broadly consistent with similar estimates of episodes of regional fluid flow and base metal mineralisation and/or remobilisation in the Mount Isa Province. <b>Citation:</b> Carson, C.J., Kositcin, N., Farkas, J., Champion, D.C., Whelan, J., Redaa, A., Gilbert. S., Henson, P.A., Maas, R., Williams, B. and Doublier, M.P., 2020. The late Paleoproterozoic Buddycurrawa Volcanics, South Nicholson region. 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.

<p>Exploring for the Future (EFTF) is a four year $100.5 million initiative by the Australian Government that aims to boost northern Australia's attractiveness as a destination for investment in resource exploration. As part of this program, Geoscience Australia has been tasked with gathering new pre-competitive data and information concerning potential mineral, energy and groundwater resources concealed beneath the surface, on an unprecedented scale. To ensure the program has the greatest impact Geoscience Australia will use innovative techniques in greenfield areas where the resource potential is completely unknown at a semi-continental scale. <p>A major EFTF output is the acquisition of deep crustal seismic reflection data. The first tranche of this was completed in early August 2017 in the region between the southern McArthur Basin to the Mt Isa western succession, crossing the South Nicholson Basin and Murphy Province. Prior to this survey, the region contained no seismic data and minimal well data. <p>This new seismic data will support exploration activities by providing a better understanding of the basin and basement architecture and structural evolution of the region, and assist in identifying geological terrains with resource potential. The preliminary processed data was released at the Annual Geoscience Exploration Seminar in March 2018 (Henson et al., 2018). This record presents the interpreted data alongside a geological summary of the region including the McArthur Basin, South Nicholson Basin and Mount Isa Orogen and provides a baseline for further studies in the region including the identification of a new sub-basin and presentation of current knowledge of the stratigraphy and geochemistry. <p>The new seismic reflection data acquired over the South Nicholson Basin as part of the Exploring for the Future program has outlined many areas of future opportunity. Geoscience Australia is currently pursuing an exciting program building upon previous work in the region, including extensive geochemical and geochronological studies aiming to build a greater understanding of the stratigraphy imaged by the seismic data. Further, our work in this region has already demonstrated the complicated and poorly understood nature of the stratigraphy and structural relationships within the region.

The South Nicholson region of northwest Queensland and the Northern Territory is the focus of a regional hydrocarbon prospectivity assessment being undertaken by the Exploring for the Future (EFTF) program, an Australian Government initiative dedicated to increasing investment in resource exploration in northern Australia. This data release provides data from new digital photography, X-ray Computerised Tomography (XCT) scanning, unconfined compressive strength (UCS) testing and laboratory ultrasonic testing for 14 samples from stratigraphic and exploration wells drilled into the South Nicholson Basin and Lawn Hill Platform in the South Nicholson region described in Jarrett et al (2020). These samples were analysed at CSIRO Geomechanics and Geophysics Laboratory in Perth during May and June 2020.

NDI Carrara 1 is a deep stratigraphic drill hole completed in 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 1120 m of Proterozoic sedimentary rocks unconformably overlain by 630 m of Cambrian Georgina Basin carbonates. Continuous cores recovered from 283 m to a total depth of 1750 m provide samples of the highest quality for a comprehensive geochemical program designed to inform on the energy and mineral prospectivity of the Carrara Sub-basin. Total Organic Carbon (TOC) contents from Rock-Eval pyrolysis of the Cambrian and Proterozoic sections demonstrate the potential for several thick black shales as source rocks and unconventional plays. Evidence for retained hydrocarbons included bituminous oil stains in centimetre-scale vugs within the Cambrian Georgina Basin and several oil bleeds within the Proterozoic section. The latter also contains surface gas with up to 2% methane concentrations measured within carbonaceous mudstones. Geochemical analyses of hydrocarbon shows highlight the occurrence of several petroleum systems operating in this frontier region. The results at NDI Carrara 1 offer the promise of a new exciting resource province in northern Australia.

NDI Carrara 1 is a deep stratigraphic drill hole (~1751m) completed in 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 report presents quantitative X-ray diffraction data undertaken by Geoscience Australia on selected rock samples, collected at roughly 4 m intervals.