SHRIMP U-Pb zircon ages are presented from 19 samples from the central and southern Thomson Orogen, northern Lachlan Orogen and Koonenberry Belt of northern New South Wales and southern Queensland. The analysed samples are predominantly (meta)sedimentary rocks, for which detrital zircon age spectra are presented, but also include selected intrusive and volcanic rocks, for which magmatic crystallisation ages are determined. The work was conducted as part of a collaborative project between Geoscience Australia (GA) and the Geological Survey of New South Wales (GSNSW) and the Geological Survey of Queensland (GSQ), with a focus on the southern Thomson Orogen.

Geoscience Australia has undertaken a regional seismic mapping study that extends into the frontier deep-water region of the offshore Otway Basin. This work builds on seismic mapping and petroleum systems modelling published in the 2021 Otway Basin Regional Study. Seismic interpretation spans over 18 000 line-km of new and reprocessed data collected in the 2020 Otway Basin seismic program and over 40 000 line-km of legacy 2D seismic data. Fault mapping has resulted in refinement and reinterpretation of regional structural elements, particularly in the deep-water areas. Structure surfaces and isochron maps highlight Shipwreck (Turonian–Santonian) and Sherbrook (Campanian–Maastrichtian) supersequence depocentres across the deep-water part of the basin. These observations will inform the characterisation of petroleum systems within the Upper Cretaceous succession, especially in the underexplored deep-water region. Presented at the 2022 Australian Petroleum Production & Exploration Association (APPEA)

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/)

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.

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 South Nicholson Basin and immediate surrounding region are situated between the Paleo- to Mesoproterozoic Mount Isa Province and McArthur Basin. Both the Mount Isa Province and the McArthur Basin are well studied; both regions host major base metal mineral deposits, and contain units prospective for hydrocarbons. In contrast, the South Nicholson Basin contains rocks that are mostly undercover, for which the basin evolution and resource potential are not well understood. To address this knowledge gap, the L210 South Nicholson Seismic Survey was acquired in 2017 in the region between the southern McArthur Basin and the western Mount Isa Province, crossing the South Nicholson Basin and Murphy Province. The primary aim of the survey was to investigate areas with low measured gravity responses (‘gravity lows’) in the region to determine whether they represent thick basin sequences, as is the case for the nearby Beetaloo Sub-basin. Key outcomes of the seismic acquisition and interpretation include (1) expanded extent of the South Nicholson Basin; (2) identification of the Carrara Sub-basin, a new basin element that coincides with a gravity low; (3) linkage between prospective stratigraphy of the Isa Superbasin (Lawn Hill Formation and Riversleigh Siltstone) and the Carrara Sub-basin; and (4) extension of the interpreted extent of the Mount Isa Province into the Northern Territory. <b>Citation:</b> Carr, L.K., Southby, C., Henson, P., Anderson, J.R., Costelloe, R., Jarrett, A.J.M., Carson, C.J., MacFarlane, S.K., Gorton, J., Hutton, L., Troup, A., Williams, B., Khider, K., Bailey, A.H.E. and Fomin, T., 2020. South Nicholson Basin seismic interpretation. 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 AusAEM1 survey is the world’s largest airborne electromagnetic survey flown to date, extending across an area exceeding 1.1 million km2 over Queensland and the Northern Territory. Approximately 60 000 line kilometres of data were acquired at a nominal line spacing of 20 km. Using this dataset, we interpreted the depth to chronostratigraphic surfaces, assembled stratigraphic relationship information, and delineated structural and electrically conductive features. Our results improved understanding of upper-crustal geology, led to 3D mapping of palaeovalleys, prompted further investigation of electrical conductors and their relationship to structural features and mineralisation, and helped us continuously connect correlative outcropping units separated by up to hundreds of kilometres. Our interpretation is designed to improve targeting and outcomes for mineral, energy and groundwater exploration, and contributes to our understanding of the chronostratigraphic, structural and upper-crustal evolution of northern Australia. More than 150 000 regional depth measurements, each attributed with detailed geological information, are an important step towards a national geological framework, and offer a regional context for more detailed, smaller-scale AEM surveys. <b>Citation:</b> Wong, S.C.T., Roach, I.C., Nicoll, M.G., English, P.M., Bonnardot, M.-A., Brodie, R.C., Rollet, N. and Ley-Cooper, A.Y., 2020. Interpretation of the AusAEM1: insights from the world’s largest airborne electromagnetic survey. 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 Precambrian Pine Creek Orogen and Arnhem Province represent two of the oldest basement terrains in northern Australia and are often considered to be devoid of major tectonic or deformational activity since the cessation of regional metamorphism in the Paleoproterozoic. A major caveat in the current hypothesis of long lived structural inactivity is the absence of published low temperature thermochronological data and thermal history models for this area. Here we report the first apatite U–Pb, fission track and (U–Th–Sm)/He data for igneous samples from both the Pine Creek Orogen and Arnhem Province, complemented with apatite geochemistry data acquired by electron microprobe and laser ablation mass spectrometry methods, and present detailed multi-kinetic low temperature thermal history models. Low-temperature thermal history models for the Pine Creek Orogen and Arnhem Province reveal a distinct phase of denudation coeval with the Paleozoic Alice Springs Orogeny, suggesting that this orogenic event impacted a larger area of the Australian crust than previously perceived. Minor localised Mesozoic thermal perturbations proximal to the Pine Creek Shear-Zone record evidence for Mesozoic reactivation contemporaneous with modelled mantle driven subsidence and the onset of sedimentation in the Money Shoal Basin, while the Arnhem Province samples demonstrate no evidence of Mesozoic thermal perturbations. <b>Citation:</b> Angus L. Nixon, Stijn Glorie, Alan S. Collins, Jo A. Whelan, Barry L. Reno, Martin Danišík, Benjamin P. Wade, Geoff Fraser; Footprints of the Alice Springs Orogeny preserved in far northern Australia: an application of multi-kinetic thermochronology in the Pine Creek Orogen and Arnhem Province. <i>Journal of the Geological Society</i> 2020;; 178 (2): jgs2020–173. doi: https://doi.org/10.1144/jgs2020-173

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 newly discovered Proterozoic depocentre in the South Nicholson region, based on interpretation from new 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 Cambrian Georgina Basin carbonates. Continuous cores recovered from 283 m to a total depth of 1751 m. Geoscience Australia conducted an extensive post-drilling analytical program that generated over 30 datasets which the interested reader can find under the EFTF webpage (under the "Data and publications" drop down menu) at https://www.eftf.ga.gov.au/south-nicholson-national-drilling-initiative This record links to the Exploring for the Future 'borehole completion report' for NDI Carrara 1 and access to all on-site downhole geophysical datasets.

Earthquake Environmental Effects (EEEs) identified in the source region of the 20th May 2016 intraplate moment magnitude (Mw) 6.1 Petermann earthquake in Central Australia are described and classified using the Environmental Seismic Intensity (ESI-07) scale. EEEs include surface rupture, ground fissures and cracks, vegetation damage, rockfalls, and displaced (jumped) bedrock fragments. The maximum ESI intensity derived from EEEs is X, consistent with previous observations from some moderate Mw crustal earthquakes. Maximum ESI isoseismals correlate with the location of the surface rupture rather than epicentre area due to the dipping geometry of the reverse source fault. ESI isoseismals encompass a larger area of the hanging-wall than the footwall, indicating stronger ground motions on the hanging-wall due to increased proximity to the rupture source and ground motion amplification effects. The maximum areal extent of secondary (seismic shaking-induced) EEEs (300 km2) is significantly smaller than expected using the published ESI-07 scale (approx. 5000 km2). This relates to the low topographic relief and relatively homogeneous bedrock geology of the study region, which (i) reduced the potential for site response amplification of strong ground motions, and (ii) reduced the susceptibility of the landscape to EEE such as landsliding and liquefaction. Erosional degradation of the observed EEE features and decreasing confidence with which they can be uniquely attributed to a seismic origin with increasing time since the earthquake highlight challenges in using many of the natural features observed herein to characterise the locations and attributes of paleo-earthquakes.