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 .

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.

To test existing geological interpretations and the regional stratigraphic relationships of the Carrara Sub-basin with adjacent resource-rich provinces, the deep stratigraphic drill hole NDI Carrara 1 was located on the western flanks of the Carrara Sub-basin, on the seismic line 17GA-SN1. The recovery of high quality near-continuous core from the Carrara Sub-basin, in concert with the spectrum of baseline analytical work being conducted by Geoscience Australia through the EFTF program, as well as other work by government and university researchers is greatly improving our understanding of this new basin. While recently published geochemistry baseline datasets have provided valuable insight into the Carrara Sub-basin, the age of the sedimentary rocks intersected by NDI Carrara 1 and their chronostratigraphic relationships with adjacent resource rich regions has remained an outstanding question. In this contribution, we present new sensitive high-resolution ion microprobe (SHRIMP) geochronology results from NDI Carrara 1 and establish regional stratigraphic correlations to better understand the energy and base-metal resource potential of this exciting frontier basin in northern Australia.

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 1100 m of Proterozoic sedimentary rocks uncomformably overlain by 630 m of Cambrian Georgina Basin carbonates. A comprehensive geochemical program designed to provide information about the region’s resource potential was carried out on samples collected at up to 4 meter intervals. This report presents data from magnetic susceptibility analyses undertaken by Geoscience Australia on selected rock samples to establish their ability to be magnetised in an applied external magnetic field.

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 petrology and clay speciation XRD conducted on of 6 selected volcaniclastic rocks taken from NDI Carrara 1 between ca. 1579 m and ca. 1653 m depth. Petrology and XRD was undertaken by Microanalysis Australia (under contract to Geoscience Australia as part of the Exploring for the Future program). Borehole completion report can be found at https://portal.ga.gov.au/bhcr/minerals/648482

The National Drilling Initiative (NDI) will manage and deliver drilling programs in multiple case study areas proposed by MinEx CRC’s partner geological survey organisations. The NDI vision is to drill multiple holes in a region to map the regional geology and architecture and define the potential for mineral systems in 3D. The areas shown in this web service describe the spatial locations of the study areas.

The National Drilling Initiative (NDI) will manage and deliver drilling programs in multiple case study areas proposed by MinEx CRC’s partner geological survey organisations. The NDI vision is to drill multiple holes in a region to map the regional geology and architecture and define the potential for mineral systems in 3D. The areas shown in this web service describe the spatial locations of the study areas.

The National Drilling Initiative (NDI) will manage and deliver drilling programs in multiple case study areas proposed by MinEx CRC’s partner geological survey organisations. The NDI vision is to drill multiple holes in a region to map the regional geology and architecture and define the potential for mineral systems in 3D. The areas shown in this web service describe the spatial locations of the study areas.

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.

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.