From 1 - 10 / 39
  • Exploring for the Future (EFTF) is an Australian Government program led by Geoscience Australia, in partnership with state and Northern Territory governments. The first phase of the EFTF program (2016-2020) aimed to drive industry investment in resource exploration in frontier regions of northern Australia by providing new precompetitive data and information about their energy, mineral and groundwater resource potential. One of the key discoveries of the first phase of the Exploring for the Future program was the identification of a large sedimentary depocentre in the South Nicholson region, an underexplored area straddling north-eastern Northern Territory and north-western Queensland. This depocentre, up to 8 km deep, was termed the ‘Carrara Sub-basin’ by Geoscience Australia. It is interpreted to contain thick sequences of Proterozoic rocks, broadly equivalent to rocks of the greater McArthur Basin (Northern Territory) and northern Lawn Hill Platform and Mount Isa Province (Queensland), known to be highly prospective for sediment-hosted base metals and unconventional hydrocarbons. In order to gain insights into the resource potential of the Carrara Sub-basin, the South Nicholson National Drilling Initiative (NDI) Carrara 1 stratigraphic drillhole was completed in late 2020, as a collaboration between Geoscience Australia, the Northern Territory Geological Survey (NTGS) and the MinEx CRC . NDI Carrara 1 is the first drillhole to intersect the, as yet, undifferentiated Proterozoic rocks of the Carrara Sub-Basin. NDI 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 mGL, intersecting ca. 630 m of Cambrian Georgina Basin overlying ca. 1100 m of Proterozoic carbonates, black shales and minor siliciclastics . Geoscience Australia is undertaking a range of investigations on the lithology, stratigraphy and geotechnical properties of NDI Carrara 1 based on wireline data, as well as undertaking a range of analyses of over 400 physical samples recovered through the entire core. This report presents new data from bulk density measurements carried out on selected rock samples as part of this comprehensive analytical program.

  • The recently drilled deep stratigraphic drill hole NDI Carrara 1 penetrates the carbonate formations of the Cambrian Georgina Basin as well as the underlying Proterozoic successions of the Carrara Sub-basin. The Proterozoic section consists predominantly of tight shales, siltstones, and calcareous clastic rocks. This study aims to assess the petrophysical properties of the Proterozoic shales using conventional wireline logs. Gamma ray and neutron-density crossplots were used to calculate shale volume fraction, and neutron-density crossplots were applied to compute the total and effective porosity of non-shale rocks. Total organic carbon (TOC) content was interpreted using artificial neural networks, and was used to derive the volume of organic matter was converted from TOC content. Bulk density logs were corrected by removing the kerogen effect in the organic-rich shales. Matrix and kerogen densities were obtained by correlating the reciprocal of grain density with TOC content. Total shale porosity was calculated from kerogen-corrected density porosity and organic porosity. Effective porosity was estimated by removing the shaliness effect. Water saturation was derived using the Simandoux equation. The Proterozoic Lawn Hill Formation in NDI Carrara 1 exhibits petrophysical properties that indicate a favourable potential for shale gas resources. Herein, we define three informal intervals within the intersected Lawn Hill Formation; the upper Lawn Hill, the Lawn Hill shale, and the lower Lawn Hill. The net shale thickness of the upper Lawn Hill and Lawn Hill shale intervals are 165 m and 149 m, respectively. The increased TOC content and organic porosity of the upper Lawn Hill and Lawn Hill shale implies higher adsorbed gas content potential. The Lawn Hill shale has the highest gas saturation (average of 31.1%) and the highest potential for free gas content, corresponding to the highest methane responses in logged mud gas profiles. This extended Abstract was submitted to/presented at the Australasian Exploration Geoscience Conference (AEGC) 2023, Brisbane (https://2023.aegc.com.au/)

  • <div>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 stratigraphic 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) 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 Georgina Basin carbonates.&nbsp;</div><div>Geoscience Australia has undertaken a range of investigations on the lithology, stratigraphy and geotechnical properties of NDI Carrara 1 as well as undertaking a range of analyses of about 500 physical samples recovered through the entire core. Analyses included geochronology, isotope studies, mineralogy, inorganic and organic geochemistry, petrophysics, geomechanics, thermal maturity and petroleum systems investigations.</div><div>Rock-Eval pyrolysis raw data undertaken by Geoscience Australia were reported in Butcher et al. (2021) on selected rock samples to establish their total organic carbon content, hydrocarbon-generating potential and thermal maturity. Interpretation of the Rock-Eval pyrolysis data concluded that a large portion of rocks within the Proterozoic section displayed unreliable Tmax values due to poorly defined S2 peaks resulting from high thermal maturity and low hydrogen content. In order to obtain more reliable Tmax values, Rock-Eval pyrolysis of selected isolated kerogens, where organic matter is concentrated and mineral matrix effects are removed, were conducted and the resulting data are presented in this report.&nbsp;</div><div><br></div>

  • <div>NDI Carrara&nbsp;1 is a 1751 m stratigraphic drill hole completed in 2020 as part of the MinEx CRC National Drilling Initiative (NDI). This campaign was a collaboration between Geoscience Australia under the Exploring for the Future program, together with MinEx CRC and the Northern Territory Geological Survey. It is the first drillhole to intersect Proterozoic rocks of the Carrara Sub-basin, a recently discovered depocentre in the South Nicholson region. The drill hole intersected ~625 m of the Paleozoic Georgina Basin, which overlies ~1120 m of Proterozoic carbonates, black shales and siliciclastic rocks, with hydrocarbon shows encountered in both the Paleozoic and Proterozoic sections. Following the completion of the drillhole, a comprehensive analytical program was carried out by Geoscience Australia to better understand the geology of the Carrara Sub-basin and its resource potential.</div><div><br></div><div>Here we present new high-resolution strontium (87Sr/86Sr), carbon (δ13C) and oxygen (δ18O) isotope data from carbonate bearing samples of the Paleozoic Georgina Basin and the Proterozoic Lawn Hill Formation intersected in NDI Carrara&nbsp;1. The aim of this data acquisition was to provide an improved understanding of the paleo-depositional environments and local/global chemostratigraphy trends recorded in the Carrara Sub-basin. </div><div><br></div><div>The majority of samples show significant alteration and thus caution should be exercised when using this data for assessing primary depositional conditions and contemporary sea-water chemistry. Despite the altered nature of most samples, samples belonging to undifferentiated Georgina Basin preserve 87Sr/86Sr ratios close to that of mid-Cambrian seawater, indicating the sampled intervals of Georgina Basin were likely connected to the global Cambrian ocean.&nbsp;Two small positive δ13C excursions (with positive shift in δ18O) within Georgina Basin samples may coincide with reported mid-Cambrian positive δ13C global marine excursions. </div><div><br></div><div>The least altered samples from the Proterozoic Lawn Hill Formation show more radiogenic 87Sr/86Sr values than the expected value of coeval mid-Proterozoic ocean at ~1600 Ma. These radiogenic 87Sr/86Sr values may reflect (i) influx of terrigenous material into a restricted basin with reduced interaction with the global ocean, or (ii) secondary overprinting by more radiogenic diagenetic fluids.</div> Abstract/Poster submitted and presented at 2023 Australian Earth Science Convention (AESC), Perth WA (https://2023.aegc.com.au/)

  • 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.

  • 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 the petrology conducted on 50 selected thin sections of NDI Carrara 1 undertaken by Microanalysis Australia (under contract to Geoscience Australia as part of the Exploring for the Future program).

  • 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.

  • 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.

  • 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 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.