In 2017, under the Federal Governments’ Exploring for the Future program, in collaboration with the NTGS under their ‘Resourcing the Territory’ initiative, Geoscience Australia acquired the South Nicholson Deep Crustal Seismic Reflection Survey in north-eastern Northern Territory. One of the key discoveries of this survey was the identification of a large sedimentary depocentre, concealed beneath the sedimentary rocks of the Cambrian Georgina Basin. This depocentre, up to 7 km deep, termed the ‘Carrara Sub-basin’ by Geoscience Australia (e.g. Carr et al., 2020), is interpreted to contain thick sequences of resource-rich Proterozoic rocks, broadly equivalent to rocks of the greater McArthur Basin (Northern Territory) and northern Lawn Hill Platform and Mount Isa Province of northwest Queensland, rocks that are highly prospective for sediment-hosted base metals and unconventional hydrocarbons. The Carrara-1 stratigraphic drillhole was completed in late 2020, as a collaboration between Geoscience Australia, the Northern Territory Geological Survey and the MinEx CRC. Carrara-1 is the first drillhole to intersect the undifferentiated Proterozoic rocks of the Carrara Sub-Basin. Carrara-1 is located on the western flanks of the Carrara Sub-basin on the South Nicholson Seismic line (17GA-SN1), 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 minor siliciclastics. These rocks preserve evidence of both oil and gas and visible disseminated sulphide mineralisation. Carrara-1 affords us a privileged glimpse into this highly prospective and exciting frontier Proterozoic basin.

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 inorganic geochemical analyses undertaken by Geoscience Australia on selected rock samples, collected at roughly 4 m intervals.

Exploring for the Future (EFTF) is an Australian Government initiative focused on gathering new data and information about potential mineral, energy and groundwater resources across northern Australia. This area is generally under-explored and offers enormous potential for industry development, as it is advantageously located close to major global markets, infrastructure and hosts many prospective regions. In June 2020, the Hon Keith Pitt MP, Minister for Resources, Water and Northern Australia, announced a four year extension to this program with an expansion in scope to cover the whole of Australia. The energy component of EFTF aims to improve our understanding of the petroleum potential of frontier Australian basins. Building an understanding of geomechanical rock properties is key to understanding both conventional and unconventional petroleum systems as well as carbon storage and sedimentary geothermal systems. Under EFTF, Geoscience Australia has undertaken geomechanical work including stress modelling, shale brittleness studies, and the acquisition of new rock property data through extensive testing on samples from the Paleo- to Mesoproterozoic South Nicholson region of Queensland and the Northern Territory and the Paleozoic Kidson Sub-basin of Western Australia. These analyses are summarised herein. Providing baseline geomechanical data in frontier basins is essential as legacy data coverage can often be inadequate for making investment decisions, particularly where unconventional plays are a primary exploration target. As EFTF increases in scope, Geoscience Australia anticipates expanding these studies to encompass further underexplored regions throughout Australia, lowering the barrier to entry and encouraging greenfield exploration. <b>Citation:</b> Bailey Adam H. E., Jarrett Amber J. M., Wang Liuqi, Dewhurst David N., Esteban Lionel, Kager Shane, Monmusson Ludwig, Carr Lidena K., Henson Paul A. (2021) Exploring for the Future geomechanics: breaking down barriers to exploration. <i>The APPEA Journal </i><b>61</b>, 579-587. https://doi.org/10.1071/AJ20039

Exploring for the Future (EFTF) is an ongoing multiyear initiative by the Australian Government, conducted by Geoscience Australia, in partnership with state and Northern Territory government agencies and other partner research institutes. The first phase of the EFTF program (2016-2020) aimed to improve Australia’s desirability for industry investment in resource exploration in frontier or ‘greenfield’ regions across northern Australia. As part of the program, Geoscience Australia employed a range of both established and innovative techniques to gather new precompetitive data and information to develop new insight into the energy, mineral and groundwater resource potential across northern Australia. To maximise impact and to stimulate industry exploration activity, Geoscience Australia focussed activities in greenfield areas where understanding of resource potential was limited. In order to address this overarching objective under the EFTF program, Geoscience Australia led acquisition of two deep crustal reflection seismic surveys in the South Nicholson region, an understudied area of little previous seismic data, straddling north-eastern Northern Territory and north-western Queensland. The first survey, L210 South Nicholson 2D Deep Crustal Seismic Survey acquired in 2017, consisted of five overlapping seismic lines (17GA-SN1 to SN5), totalling ~1100 line-km. Survey L210 linked directly into legacy Geoscience Australia seismic lines (06GA-M1 and 06GA-M2) in the vicinity of the world-class Pb-Zn Century Mine in Queensland. The results from survey L210 profoundly revised our geological understanding of the South Nicholson region, and led to the key discovery of an extensive sag basin, the Carrara Sub-basin, containing highly prospective late Paleoproterozoic to Mesoproterozoic rocks with strong affinities with the adjacent Mount Isa Province and Lawn Hill Platform. To complement and expand on the outstanding success of the South Nicholson survey and to continue to explore the resource potential across the underexplored and mostly undercover South Nicholson and Barkly regions, a second seismic survey was acquired in late 2019, the Barkly 2D reflection survey (L212). The Barkly seismic survey comprises five intersecting lines (19GA-B1 to B5), totalling ~813 line-km, extending from the NT-QLD border in the south-east, near Camooweal, to the highly prospective Beetaloo Sub-basin in the north-west. The survey ties into the South Nicholson survey (L210), the recently acquired Camooweal 2D reflection seismic survey by the Geological Survey of Queensland and industry 2D seismic in the Beetaloo Sub-basin, leveraging on and maximising the scientific value and impact on all surveys. The Barkly reflection seismic data images the south-western margin of the Carrara Sub-basin and identified additional previously unrecognised, structurally-disrupted basins of Proterozoic strata, bounded by broadly northeast trending basement highs. Critically, the survey demonstrates the stratigraphic continuity of highly prospective Proterozoic strata from the Beetaloo Sub-basin into these newly discovered, but as yet unevaluated, concealed basins and into the Carrara Sub-basin, further attesting to the regions outstanding potential for mineral and hydrocarbon resources. This survey, in concert with the South Nicholson seismic survey and other complementary EFTF funded regional geochemical, geochronology and geophysical data acquisition surveys, significantly improves our understanding of the geological evolution, basin architecture and the resource potential of this previously sparsely studied region.

A comprehensive geochemical program was carried out on rock samples collected in the NDI Carrara 1 drill hole, the first stratigraphic test of the newly discovered Carrara Sub-basin located in the South Nicholson region of northern Australia. The drill hole recovered continuous core from 284 m to total depth at 1750 m and intersected approximately 1120 m of Proterozoic sedimentary rocks, unconformably overlain by 630 m of Cambrian Georgina Basin carbonate-rich rocks. Total organic carbon (TOC) contents from Rock-Eval pyrolysis highlight the potential for several thick black shales to be a source of petroleum for conventional and unconventional plays. Cambrian rocks contain an organic-rich section with TOC contents of up to 4.7 wt.% and excellent oil-generating potential. The Proterozoic section is overmature for oil generation but mature for gas generation, with potential for generating gas in carbonaceous mudstones showing TOC contents up to 5.5 wt.% between 680 and 725 m depth. A sustained release of methane (up to 2%) recorded during drilling from 1150 to 1500 m suggests potential for an unconventional gas system in the Proterozoic rocks from 950 to 1415 m depth, which exhibit favourable organic richness and thermal maturity. The Proterozoic rocks, which are comparable in age to the sediment-hosted deposits of the Century Mine, contain local occurrences of lead, zinc and copper sulfide minerals providing hints of mineralisation. The combined geochemical results offer the promise of a potential new resource province in northern Australia. <b>Citation:</b> E. Grosjean, A.J.M. Jarrett, C.J. Boreham, L. Wang, L. Johnson, J.M. Hope, P. Ranasinghe, J.J. Brocks, A.H.E. Bailey, G.A. Butcher, C.J. Carson, Resource potential of the Proterozoic–Paleozoic Carrara depocentre, South Nicholson region, Australia: Insights from stratigraphic drilling, <i>Organic Geochemistry</i>, Volume 186, 2023, 104688, ISSN 0146-6380, DOI: https://doi.org/10.1016/j.orggeochem.2023.104688.

<div>The South Nicholson National Drilling Initiative (NDI) Carrara 1 stratigraphic drill hole was completed in late 2020, as a collaboration between Geoscience Australia, the Northern Territory Geological Survey (NTGS), and the MinEx CRC. The drilling aimed to gather new subsurface data on the potential mineral and energy resources in the newly identified Carrara Sub-basin. NDI Carrara 1 is located in the eastern Northern Territory, on the western flanks of the Carrara Sub-basin on the South Nicholson Seismic line, 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 minor siliciclastics (https://portal.ga.gov.au/bhcr/minerals/648482).</div><div>&nbsp;</div><div>Following a public data release of the borehole completion report, CSIRO was contracted by Geoscience Australia (GA) under the Exploring for the Future program to analyse samples from NDI Carrara 1 for quantitative bulk and clay fraction analysis. This report presents results for quantitative bulk and clay (<2 µm) fraction analysis by X-ray powder diffraction (XRD) on 32 bulk core samples from the NDI Carrara 1. Samples were prepared and analysed at the CSIRO’s Waite Laboratories in South Australia.</div><div><br></div>

<div>NDI Carrara 1 is a deep stratigraphic borehole that was drilled in 2020 under the MinEx CRC’s National Drilling Initiative (NDI) program in collaboration with Geoscience Australia and the Northern Territory Geological Survey. NDI Carrara 1 is the first stratigraphic test of the recently described Carrara Sub-basin, a Proterozoic aged depocentre located in the South Nicholson region of northwest Queensland and the Northern Territory. The borehole was drilled to a total depth of 1751 m and penetrated a succession of Cambrian aged Georgina Basin carbonate and siliciclastic rocks that unconformably overly a thick succession of Proterozoic age siliciclastic and carbonate-rich sediments. Although drilled on the western flank of the Carrara Sub-basin, NDI Carrara 1 did not penetrate to basement. Interpretation of the L210 deep-crustal seismic survey suggests that further Proterozoic sedimentary packages known from the northern Lawn Hill Platform in northwest Queensland are likely to be found underlying the succession intersected in NDI Carrara 1. The borehole was continuously cored from 283 m to total depth, and an extensive suite of wireline logs was acquired. Geoscience Australia and partners have undertaken an extensive analytical program to understand the depositional, structural, and diagenetic history of the sediments intersected in NDI Carrara 1. This program includes a targeted geomechanical study that aims to characterise the physical properties of these Proterozoic rocks through laboratory analysis of core samples, the results of which are summarised in this data release.</div><div><br></div><div>This data release provides data from new unconfined compressive strength (UCS), single-stage triaxial testing, and laboratory ultrasonic testing for 36 sample plugs from NDI Carrara 1. These tests were performed at the CSIRO Geomechanics and Geophysics Laboratory in Perth, during January to June 2022. The full results as provided by CSIRO to Geoscience Australia are provided as an attachment to this document.&nbsp;</div>

<div>The Carrara Sub-basin, discovered in 2017 based on interpretation of 2D deep seismic surveys acquired by Geoscience Australia, is a large sedimentary depocentre in the South Nicholson region straddling the Northern Territory and Queensland. It was interpreted to contain up to 8 km of Paleoproterozoic to Cambrian rocks including stratigraphic equivalents to the Isa Superbasin, South Nicholson Group and Georgina Basin. In order to validate these stratigraphic interpretations and assess the resource prospectivity of the Carrara Sub-basin, the South Nicholson National Drilling Initiative (NDI) Carrara 1 stratigraphic drill hole was completed in late 2020 as a collaboration between the MinEx Cooperative Research Centre, Geoscience Australia and the Northern Territory Geological Survey. NDI Carrara 1 was drilled on the western flanks of the Carrara Sub-basin and reached a total depth of 1751&nbsp;m, intersecting ca. 630&nbsp;m of Cambrian Georgina Basin overlying ca. 1100&nbsp;m of Proterozoic carbonates, black shales and minor siliciclastics. More than 400 NDI Carrara&nbsp;1 physical samples were analysed as part of an extensive geochemical program, including Rock-Eval pyrolysis and compositional analyses of hydrocarbon shows, whose results and implications for energy prospectivity are summarised here.</div> This Abstract was submitted/presented to the 2022 Australian Organic Geochemistry Conference 27-29 November (https://events.csiro.au/Events/2022/October/5/Australian-Organic-Geochemistry-Conference)

The first phase of the Australian Government's Exploring for the Future (EFTF) was a multi-year (2016-2020) $100.5 million initiative to increase northern Australia's desirability as a destination for industry investment to stimulate ‘greenfield’ resource exploration. In order to support this fundamental objective of the EFTF program, Geoscience Australia conducted acquisition of a diverse range of new precompetitive datasets across northern Australia, focussing on regions of unrecognised mineral, energy and groundwater resource potential. The Barkly 2D Deep Crustal Reflection Seismic Survey (L212) was acquired in 2019 as a major objective of the EFTF program in partnership with, and co-funded by, the NT Government under the Resourcing the Territory initiative. The Barkly Seismic Survey extends from the newly discovered Carrara Sub-basin in the South Nicholson Basin region to the south-eastern margins of the Beetaloo Sub-basin (Fomin, T., et al. 2019). The Barkly Seismic Survey images interpreted Paleoproterozoic to Mesoproterozoic successions extending from the Carrara Sub-basin to the highly prospective Beetaloo Sub-basin of the McArthur Basin. These successions are concealed by a persistent cover of up to 600 m of Paleozoic Georgina Basin sediments. Interpretation of the Barkly Seismic Survey established three informal geological domains, each defined by structural elements and/or basin characteristics (Southby et al, 2021). This data set contains an exported set of XYZ points from interpreted horizons (Southby et al 2022,) on the Barkly Seismic Survey (L212) in both two way time (TWT ms on PreSTM_19ga lines) and depth (m) re-interpreted on depth indexed PreSDM_19GA lines. The coordinate reference system for this dataset is WGS 1984 Australian Centre for Remote Sensing Lambert. Seismic reference datum is 350 m. The seismic reference datum are described in the EBCDIC headers of the SEGY files for each of the survey lines. Fomin, T., Costelloe, R.D., Holzschuh, J. 2019. L212 Barkly 2D Seismic Survey. Geoscience Australia, Canberra. https://pid.geoscience.gov.au/dataset/ga/132890 Southby, C., Rollet, N., Carson, C., Carr, L., Henson, P., Fomin, T., Costelloe, R., Doublier, M., Close, D. 2021. The Exploring for the Future 2019 Barkly Reflection Seismic Survey: Key discoveries and implication for resources. Geoscience Australia, Canberra. https://pid.geoscience.gov.au/dataset/ga/145107 Southby, C., Carson, C.J., Fomin, T., Rollet, N., Henson, P.A., Carr, L.K., Doublier, M.P., Close, D. 2022. Exploring for the Future - The 2019 Barkly Reflection Seismic Survey (L212). RECORD: 2022/009. Geoscience Australia, Canberra. http://dx.doi.org/10.11636/Record.2022.009

Stratigraphic drill hole NDI Carrara 1 was drilled as a collaboration between Geoscience Australia (GA), the Northern Territory Geological Survey (NTGS) and the Mineral Exploration Cooperative Research Centre (MinEx CRC). It reached a total depth of 1751 m in late 2020 and is the first drill hole to intersect the undifferentiated Proterozoic rocks of the Carrara Sub-Basin. It intersected approximately 630 m of Cambrian Georgina Basin sedimentary rocks overlying the ~1100 m of Proterozoic carbonates, black shales and other siliciclastics of the Carrara Sub-Basin succession. The formational assignments of the Georgina Basin succession are preliminary and were assigned in the field. The units intersected comprise the Border Waterhole Formation (~531m to ~630m), which is overlain by the Currant Bush Limestone (~249m to ~531m), which in turn is overlain by the Camooweal Dolostone (0m to ~249m). Of these, only the lower 80% of the Currant Bush Limestone and the entire Border Waterhole Formation were cored. This report presents biostratigraphic results from macrofossil examination of NDI Carrara 1 core samples within the Georgina Basin section.