This record presents new zircon U-Pb geochronological data, obtained via Sensitive High Resolution Ion Microprobe (SHRIMP) for eleven samples of plutonic and volcanic rocks from the Lachlan Orogen, and the New England Orogen. The work is part of an ongoing Geochronology Project (Metals in Time), conducted by the Geological Survey of New South Wales (GSNSW) and Geoscience Australia (GA) under a National Collaborative Framework (NCF) agreement, to better understand the geological evolution of New South Wales. The results herein (summarised in Table 1.1 and Table 1.2) correspond to zircon U-Pb SHRIMP analysis undertaken on GSNSW mineral systems projects for the reporting period July 2015-June 2016. Lachlan Orogen In the Lachlan Orogen, the age of 418.9 ± 2.5 Ma for the Babinda Volcanics is consistent with the accepted stratigraphy of its parent Kopyje Group, agrees with the ages of other I-type volcanic rocks within the Canbelego-Mineral Hill Volcanic Belt and indicates eruption and emplacement of this belt during a single event. The age of the Shuttleton Rhyolite Member (421.9 ± 2.7 Ma) of the Amphitheatre Group is compatible with recent U-Pb dating of the Mount Halfway Volcanics, which interfingers with the Amphitheatre Group (MacRae, 1987). The age is also similar to nearby S-type granite intrusions, which suggests that the limited eruptive volcanic activity in the region was accompanied by local coeval plutonism. The results for the Babinda Volcanics and Shuttleton Rhyolite Member, in conjunction with previous GA dating and other dating and studies (summarised in Downes et al., 2016) establishes that significant igneous activity occurred between ~423 and ~418 Ma within the Cobar region but comprised two compositionally distinct but broadly contemporaneous belts of volcanics and comagmatic granite intrusions. The new age for the unnamed quartz monzonite at Hobbs Pipe constrains the maximum age of the hosted gold mineralisation to 414.7 ± 2.6 Ma. The wide range in ages for granites along the Gilmore Suture suggests that mineralisation in this region is not necessarily constrained to a single short-lived event. The new age of 413.5 ± 2.3 Ma for volcanics at Yerranderie indicates that that the Bindook Volcanic Complex was erupted over a relatively short period, and also indicates that the epithermal mineralisation at Yerranderie was not genetically related to the host volcanics but probably to a younger rifting event in the east Lachlan. New England Orogen Four units were dated from the Clarence River Supersuite in the New England Orogen. All four are between 255 and 256 Ma, demonstrating that these granites are related chemically, spatially, and temporally. While these four ages are indistinguishable, the current age span for Clarence River Supersuite is more than 40 million years. This wide age range indicates that classification of granites into the Clarence River Supersuite needs further refinement. The new age for the Newton Boyd Granodiorite (252.8 ± 1.0 Ma) is similar to some previously dated units within the Herries Supersuite, but both the Herries Supersuite and Stanthorpe Supersuite (into which the Herries Supersuite was reclassified by Donchak, 2013) incorporate units with a broad range of ages: the age distribution for the Stanthorpe Supersuite spans 50 million years. Classification of granites in the New England Orogen in New South Wales is worth revisiting. Two units were dated from the Drake Volcanics, nominally in the Wandsworth Volcanic Group and indicate that the middle to upper section of the Drake Volcanics, including the mineralising intrusions, were emplaced within the space of 1-2 million years. These results support a genetic and temporal link between the Au-Ag epithermal mineralisation at White Rock and Red Rock and their host Drake Volcanic packages rather than to younger regional plutonism (i.e., Stanthorpe Supersuite) or volcanism (i.e., Wandsworth Volcanics). The almost 10 Ma gap between the Drake Volcanics and the next lowest units of the Wandsworth Volcanic Group supports the argument for considering the Drake Volcanics a distinct unit.

The Pre-Cenozoic Geology of South Australia, New South Wales and Victoria removes Cenozoic geology. It is largely based on (1) the 1:1,000,000 Surface Geology by Geoscience Australia (2012) for New South Wales; (2) the Victoria seamless geology (2014); and (3) solid geology layers of South Australia by the Geological Survey of South Australia (2016), plus interpretation in GA of potential filed geophysical datasets, particularly magnetic data. The South Australia solid geology layers available on SARIG were used for Archaean to Ordovician geology of the state. Post-Ordovician geology of South Australia were interpreted in GA using magnetic data. The 1:1,000,000 surface geology map of the Mount Painter Region by S.B. Hore (2015) was also used. Solid geology was produced with the aid of interpretation of magnetic data for that region. For the Murray Basin and surrounding areas drill hole data were used to determine the geology under cover. Because extents of drill hole intercepted geology are not know in most cases. Such geology are shown as tiny circular polygons. The author thanks a number of state and GA geologists for their inputs at various stages of the project, particularly those who reviewed the data.

<div>This dataset represents the second version of a compilation of borehole stratigraphic unit data on a national scale (Figure 1). It builds on the previous Australian Borehole Stratigraphic Units Compilation (ABSUC) Version 1.0 (Vizy &amp; Rollet, 2023a) with additional new or updated stratigraphic interpretation on key boreholes located in Figure 2. Its purpose is to consolidate and standardise publicly accessible information from boreholes, including those related to petroleum, stratigraphy, minerals, and water. This compilation encompasses data from states and territories, as well as less readily available borehole logs and interpretations of stratigraphy.</div><div>&nbsp;</div><div>This study was conducted as part of the National Groundwater Systems (NGS) Project within the Australian Government's Exploring for the Future (EFTF) program. Geoscience Australia’s Exploring for the Future program provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia’s transition to net zero emissions, strong, sustainable resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government. More information is available at http://www.ga.gov.au/eftf and https://www.eftf.ga.gov.au/national-groundwater-systems.</div><div>&nbsp;</div><div>As our understanding of Australian groundwater systems expands across states and territories, including legacy data from the 1970s and recent studies, it becomes evident that there is significant geological complexity and spatial variability in stratigraphic and hydrostratigraphic units nationwide. Recognising this complexity, there is a need to standardise diverse datasets, including borehole location and elevation, as well as variations in depth and nomenclature of stratigraphic picks. This standardisation aims to create a consistent, continent-wide stratigraphic framework for better understanding groundwater system for effective long-term water resource management and integrated resource assessments.</div><div>&nbsp;</div><div>This continental-scale compilation consolidates borehole data from 53 sources, refining 1,117,693 formation picks to 1,010,483 unique records from 171,396 boreholes across Australia. It provides a consistent framework for interpreting various datasets, enhancing 3D aquifer geometry and connectivity. Each data source's reliability is weighted, prioritising the most confident interpretations. Geological units conform to the Australian Stratigraphic Units Database (ASUD) for efficient updates. Regular updates are necessary to accommodate evolving information. Borehole surveys and dip measurements are excluded. As a result, stratigraphic picks are not adjusted for deviation, potentially impacting true vertical depth in deviated boreholes.</div><div>&nbsp;</div><div>This dataset provides:</div><div>ABSUC_v2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Australian stratigraphic unit compilation dataset (ABSUC)</div><div>ABSUC_v2_TOP&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;A subset of preferred top picks from the ABSUC_v2 dataset</div><div>ABSUC_v2_BASE&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;A subset of preferred base picks from the ABSUC_v2 dataset</div><div>ABSUC_BOREHOLE_v2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;ABSUC Borehole collar dataset</div><div>ASUD_2023&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;A subset of the Australia Stratigraphic Units Database (ASUD)</div><div>&nbsp;</div><div>Utilising this uniform compilation of stratigraphic units, enhancements have been made to the geological and hydrogeological surfaces of the Great Artesian Basin, Lake Eyre Basin and Centralian Superbasin. This compilation is instrumental in mapping various regional groundwater systems and other resources throughout the continent. Furthermore, it offers a standardised approach to mapping regional geology, providing a consistent foundation for comprehensive resource impact assessments.</div>

<div>This data package contains interpretations of airborne electromagnetic (AEM) conductivity sections in the Exploring for the Future (EFTF) program’s Eastern Resources Corridor (ERC) study area, in south eastern Australia. Conductivity sections from 3 AEM surveys were interpreted to provide a continuous interpretation across the study area – the EFTF AusAEM ERC (Ley-Cooper, 2021), the Frome Embayment TEMPEST (Costelloe et al., 2012) and the MinEx CRC Mundi (Brodie, 2021) AEM surveys. Selected lines from the Frome Embayment TEMPEST and MinEx CRC Mundi surveys were chosen for interpretation to align with the 20&nbsp;km line-spaced EFTF AusAEM ERC survey (Figure 1).</div><div>The aim of this study was to interpret the AEM conductivity sections to develop a regional understanding of the near-surface stratigraphy and structural architecture. To ensure that the interpretations took into account the local geological features, the AEM conductivity sections were integrated and interpreted with other geological and geophysical datasets, such as boreholes, potential fields, surface and basement geology maps, and seismic interpretations. This approach provides a near-surface fundamental regional geological framework to support more detailed investigations. </div><div>This study interpreted between the ground surface and 500&nbsp;m depth along almost 30,000 line kilometres of nominally 20&nbsp;km line-spaced AEM conductivity sections, across an area of approximately 550,000&nbsp;km2. These interpretations delineate the geo-electrical features that correspond to major chronostratigraphic boundaries, and capture detailed stratigraphic information associated with these boundaries. These interpretations produced approximately 170,000 depth estimate points or approximately 9,100 3D line segments, each attributed with high-quality geometric, stratigraphic, and ancillary data. The depth estimate points are formatted for compliance with Geoscience Australia’s (GA) Estimates of Geological and Geophysical Surfaces (EGGS) database, the national repository for standardised depth estimate points. </div><div>Results from these interpretations provided support to stratigraphic drillhole targeting, as part of the Delamerian Margins NSW National Drilling Initiative campaign, a collaboration between GA’s EFTF program, the MinEx CRC National Drilling Initiative and the Geological Survey of New South Wales. The interpretations have applications in a wide range of disciplines, such as mineral, energy and groundwater resource exploration, environmental management, subsurface mapping, tectonic evolution studies, and cover thickness, prospectivity, and economic modelling. It is anticipated that these interpretations will benefit government, industry and academia with interest in the geology of the ERC region.</div>

<div>Groundwater dependent ecosystems (GDEs) rely on access to groundwater on a permanent or intermittent basis to meet some or all of their water requirements (Richardson et al., 2011). The <a href="https://explorer-aws.dea.ga.gov.au/products/ga_ls_tc_pc_cyear_3">Tasselled Cap percentile products</a> created by Digital Earth Australia (2023) were used to identify potential GDEs for the upper Darling River floodplain study area. These percentile products provide statistical summaries (10th, 50th, 90th percentiles) of landscape brightness, greenness and wetness in imagery acquired between 1987 and present day. The 10th percentile greenness and wetness represent the lowest 10% of values for the time period evaluated, e.g. 10th greenness represents the least green period. In arid regions, areas that are depicted as persistently green and/or wet at the 10th percentile have the greatest potential to be GDEs. For this reason, and due to accessibility of the data, the 10th percentile Tasselled Cap greenness (TCG) and Tasselled Cap wetness (TCW) products were used as the basis for the assessment of GDEs for the upper Darling River floodplain study area. </div><div><br></div><div>This data release is an ESRI geodatabase, with layer files, including:</div><div><br></div><div>-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;original greenness and wetness datasets extracted; </div><div><br></div><div>-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;classified 10th percentile greenness and wetness datasets (used as input for the combined dataset); </div><div><br></div><div>-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;combined scaled 10th percentile greenness and wetness dataset (useful for a quick glance to identify potential groundwater dependent vegetation (GDV) that have high greenness and wetness e.g. river red gums)</div><div><br></div><div>-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;combined classified 10th percentile greenness and wetness dataset (useful to identify potential GDV/GDE and differentiate between vegetation types)</div><div><br></div><div>-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;coefficient of variation of 50th percentile greenness dataset (useful when used in conjunction with the scaled/combined products to help identify GDEs)</div><div><br></div><div>For more information and detail on these products, refer to <a href="https://dx.doi.org/10.26186/148545">https://dx.doi.org/10.26186/148545</a>.</div><div><br></div><div><strong>References</strong></div><div>Digital Earth Australia (2023). <em><a href="https://docs.dea.ga.gov.au">Digital Earth Australia User Guide</a></em>. </div><div>Richardson, S., E. Irvine, R. Froend, P. Boon, S. Barber, and B. Bonneville. 2011a. <em>Australian groundwater-dependent ecosystem toolbox part 1: Assessment framework.</em> Waterlines Report 69. Canberra, Australia: Waterlines.</div>

This data package, completed as part of Geoscience Australia’s National Groundwater Systems (NGS) Project, presents results of the second iteration of the 3D Great Artesian Basin (GAB) and Lake Eyre Basin (LEB) (Figure 1) geological and hydrogeological models (Vizy & Rollet, 2023) populated with volume of shale (Vshale) values calculated on 2,310 wells in the Surat, Eromanga, Carpentaria and Lake Eyre basins (Norton & Rollet, 2023). This provides a refined architecture of aquifer and aquitard geometry that can be used as a proxy for internal, lateral, and vertical, variability of rock properties within each of the 18 GAB-LEB hydrogeological units (Figure 2). These data compilations and information are brought to a common national standard to help improve hydrogeological conceptualisation of groundwater systems across multiple jurisdictions. This information will assist water managers to support responsible groundwater management and secure groundwater into the future. This 3D Vshale model of the GAB provides a common framework for further data integration with other disciplines, industry, academics and the public and helps assess the impact of water use and climate change. It aids in mapping current groundwater knowledge at a GAB-wide scale and identifying critical groundwater areas for long-term monitoring. The NGS project is part of the Exploring for the Future (EFTF) program—an eight-year, $225 million Australian Government funded geoscience data and precompetitive information acquisition program. The program seeks to inform decision-making by government, community, and industry on the sustainable development of Australia's mineral, energy, and groundwater resources, including those to support the effective long-term management of GAB water resources. This work builds on the first iteration completed as part of the Great Artesian Basin Groundwater project (Vizy & Rollet, 2022; Rollet et al., 2022), and infills previous data and knowledge gaps in the GAB and LEB with additional borehole, airborne electromagnetic and seismic interpretation. The Vshale values calculated on additional wells in the southern Surat and southern Eromanga basins and in the whole of Carpentaria and Lake Eyre basins provide higher resolution facies variability estimates from the distribution of generalised sand-shale ratio across the 18 GAB-LEB hydrogeological units. The data reveals a complex mixture of sedimentary environments in the GAB, and highlights sand body development and hydraulic characteristics within aquifers and aquitards. Understanding the regional extents of these sand-rich areas provides insights into potential preferential flow paths, within and between the GAB and LEB, and aquifer compartmentalisation. However, there are limitations that require further study, including data gaps and the need to integrate petrophysics and hydrogeological data. Incorporating major faults and other structures would also enhance our understanding of fluid flow pathways. The revised Vshale model, incorporating additional boreholes to a total of 2,310 boreholes, contributes to our understanding of groundwater flow and connectivity in the region, from the recharge beds to discharge at springs, and Groundwater Dependant Ecosystems (GDEs). It also facilitates interbasinal connectivity analysis. This 3D Vshale model offers a consistent framework for integrating data from various sources, allowing for the assessment of water use impacts and climate change at different scales. It can be used to map groundwater knowledge across the GAB and identify areas that require long-term monitoring. Additionally, the distribution of boreholes with gamma ray logs used for the Vshale work in each GAB and LEB units (Norton & Rollet, 2022; 2023) is used to highlight areas where additional data acquisition or interpretation is needed in data-poor areas within the GAB and LEB units. The second iteration of surfaces with additional Vshale calculation data points provides more confidence in the distribution of sand bodies at the whole GAB scale. The current model highlights that the main Precipice, Hutton, Adori-Springbok and Cadna-owie‒Hooray aquifers are relatively well connected within their respective extents, particularly the Precipice and Hutton Sandstone aquifers and equivalents. The Bungil Formation, the Mooga Sandstone and the Gubberamunda Sandstone are partial and regional aquifers, which are restricted to the Surat Basin. These are time equivalents to the Cadna-owie–Hooray major aquifer system that extends across the Eromanga Basin, as well as the Gilbert River Formation and Eulo Queen Group which are important aquifers onshore in the Carpentaria Basin. The current iteration of the Vshale model confirms that the Cadna-owie–Hooray and time equivalent units form a major aquifer system that spreads across the whole GAB. It consists of sand bodies within multiple channel belts that have varying degrees of connectivity' i.e. being a channelised system some of the sands will be encased within overbank deposits and isolated, while others will be stacked, cross-cutting systems that provide vertical connectivity. The channelised systemtransitions vertically and laterally into a shallow marine environment (Rollet et al., 2022). Sand-rich areas are also mapped within the main Poolowanna, Brikhead-Walloon and Westbourne interbasinal aquitards, as well as the regional Rolling Downs aquitard that may provide some potential pathways for upward leakage of groundwater to the shallow Winton-Mackunda aquifer and overlying Lake Eyre Basin. Further integration with hydrochemical data may help groundtruth some of these observations. This metadata document is associated with a data package including: • Seventeen surfaces with Vshale property (Table 1), • Seventeen surfaces with less than 40% Vshale property (Table 2), • Twenty isochore with average Vshale property (Table 3), • Twenty isochore with less than 40% Vshale property (Table 4), • Sixteen Average Vshale intersections of less than 40% Vshale property delineating potential connectivity between isochore (Table 5), • Sixteen Average Vshale intersections of less than 40% Vshale property delineating potential connectivity with isochore above and below (Table 6), • Seventeen upscaled Vshale log intersection locations (Table 7), • Six regional sections showing geology and Vshale property (Table 8), • Three datasets with location of boreholes, sections, and area of interest (Table 9).

<b>This data package is superseded by a second iteration presenting updates on 3D geological and hydrogeological surfaces across eastern Australia that can be accessed through </b><a href="https://dx.doi.org/10.26186/148552">https://dx.doi.org/10.26186/148552</a> The Australian Government, through the National Water Infrastructure Fund – Expansion, commissioned Geoscience Australia to undertake the project ‘Assessing the Status of Groundwater in the Great Artesian Basin’ (GAB). The project commenced in July 2019 and will finish in June 2022, with an aim to develop and evaluate new tools and techniques to assess the status of GAB groundwater systems in support of responsible management of basin water resources. While our hydrogeological conceptual understanding of the GAB continues to grow, in many places we are still reliant on legacy data and knowledge from the 1970s. Additional information provided by recent studies in various parts of the GAB highlights the level of complexity and spatial variability in hydrostratigraphic units across the basin. We now recognise the need to link these regional studies to map such geological complexity in a consistent, basin-wide hydrostratigraphic framework that can support effective long-term management of GAB water resources. Geological unit markers have been compiled and geological surfaces associated with lithostratigraphic units have been correlated across the GAB to update and refine the associated hydrogeological surfaces. Recent studies in the Surat Basin in Queensland and the Eromanga Basin in South Australia are integrated with investigations from other regions within the GAB. These bodies of work present an opportunity to link regional studies and develop a revised, internally consistent geological framework to map geological complexity across the GAB. Legacy borehole data from various sources, seismic and airborne electromagnetic (AEM) data were compiled, then combined and analysed in a common 3D domain. Correlation of interpreted geological units and stratigraphic markers from these various data sets are classified using a consistent nomenclature. This nomenclature uses geological unit subdivisions applied in the Surat Cumulative Management Area (OGIA (Office of Groundwater Impact Assessment), 2019) to correlate time equivalent regional hydrogeological units. Herein we provide an update of the surface extents and thicknesses for key hydrogeological units, reconciling geology across borders and providing the basis for a consistent hydrogeological framework at a basin-wide scale. The new surfaces can be used for facilitating an integrated basin systems assessment to improve our understanding of potential impacts from exploitation of sub-surface resources (e.g., extractive industries, agriculture and injection of large volumes of CO2 into the sub-surface) in the GAB and providing a basis for more robust water balance estimates. This report is associated with a data package including (Appendix A – Supplementary material): • Nineteen geological and hydrogeological surfaces from the Base Permo-Carboniferous, Top Permian, Base Jurassic, Base Cenozoic to the surface (Table 2.1), • Twenty-one geological and hydrogeological unit thickness maps from the top crystalline basement to the surface (Figure 3.7 to Figure 3.27), • The formation picks and constraining data points (i.e., from boreholes, seismic, AEM and outcrops) compiled and used for gridding each surface (Table 3.8).

<div>This record presents nine new zircon and titanite U–Pb geochronological data, obtained via Sensitive High Resolution Ion Microprobe (SHRIMP) for seven samples of plutonic rocks from the Lachlan Orogen and the Cobar Basin, plus one garnet-bearing skarn vein from the Cobar region. Many of these new ages improve existing constraints on the timing of mineralisation in the Cobar Basin, as part of an ongoing Geochronology Project (Metals in Time), conducted by the Geological Survey of New South Wales (GSNSW) and Geoscience Australia (GA) under a National Collaboration Framework (NCF) agreement. The results herein (summarised in Table 1.1) correspond to zircon and titanite U–Pb SHRIMP analysis undertaken on GSNSW Mineral Systems projects over July 2017–June 2019.</div><div><br></div><div>Our new data establish an episode of c. 427–425 Ma I-type plutonism, coeval with regional S-type granites, which marginally predated opening of the Cobar Basin. Widespread S-type and high-level I-type magmatism accompanied 423–417 Ma basin development. At least two episodes of skarn-related mineralisation are recognised in the southern Cobar Basin: c. 387 Ma (from pre-mineralisation skarn veins) at Kershaws prospect, and c. 403 Ma at the adjacent Hera mine (Fitzherbert et al., 2021).</div><div><br></div><div>Three intrusive rocks were dated at the Norma Vale prospect in the southwestern Cobar Basin, where calcic iron-copper skarn mineralisation is thought to have been caused by I-type but compositionally complex high-level intrusive rocks emplaced along a northeast-oriented fault related to the nearby Rookery Fault (Fitzherbert et al., 2017). A 423 ± 8 Ma I-type quartz diorite potentially constrains the timing of skarn mineralisation, but is indistinguishable in age from a 421.3 ± 3.0 Ma S-type cordierite-biotite granite and a 417.5 ± 3.3 Ma coarse-grained S-type granite, both from deeper in the same drillhole. These results suggest that at least some of the coeval S-type and high-level I-type magmatic activity accompanying opening of the Cobar Basin was associated with early mineralisation, although skarn-forming processes regionally are complex and episodic (Fitzherbert et al., 2021).</div><div><br></div><div>In the Cobar mining belt, our new date of 422.8 ± 2.8 Ma for I-type rhyolitic porphyry at Carissa Shaft (which is one of the southernmost high-level intrusions associated with the Perseverance and Queen Bee orebodies) is coeval with the 423.2 ± 3.5 Ma ‘Peak rhyolite’ (Black, 2007), but marginally older than the 417.6 ± 3.0 Ma Queen Bee Porphyry (Black, 2005). At Gindoono, a 423.0&nbsp;±&nbsp;2.6&nbsp;Ma unnamed dacitic porphyry intruded and hornfelsed the undated I-type Majuba Volcanics, thereby establishing a minimum age for that unit.</div><div><br></div><div>East of Cobar, the I-type Wild Wave Granodiorite intruded the Ordovician Girilambone Group, but was exhumed and eroded to form clasts within pebble conglomerates of the lowermost Cobar Basin. Its new U–Pb SHRIMP zircon age of 424.1 ± 2.8 Ma constrains the timing of I-type plutonism which marginally predated formation of the Cobar Basin. A similar zircon age of 426.7 ± 2.3 Ma was obtained from the concealed Fountaindale Granodiorite north of Condoblin, indicating that this I-type pluton is coeval with the nearby and much larger c. 427 Ma S-type Erimeran Granite. Titanite from the same sample of Fountaindale Granodiorite yielded an age of 421.6 ± 2.7 Ma, which is significantly younger than the zircon age, and is interpreted to constrain the timing of ‘deuteric’ (chlorite-albite-epidote-titanite-sericite-carbonate) alteration during post-magmatic hydrothermal activity (e.g. Blevin, 2003b).</div><div><br></div><div>A garnet-bearing skarn vein at Kershaws prospect, adjacent to the Hera orebody (Fitzherbert et al., 2021), predates the main phase of mineralisation, and yielded a titanite age of 387.2 ±&nbsp;6.2&nbsp;Ma. This indicates that the skarn-forming hydrothermal event at Kershaws prospect is significantly younger than the c. 403 Ma age for the main mineralising event at Hera mine (Fitzherbert et al., 2021).</div>

The Great Artesian Basin Research Priorities Workshop, organised by Geoscience Australia (GA), was held in Canberra on 27 and 28 April 2016. Workshop attendees represented a spectrum of stakeholders including government, policy, management, scientific and technical representatives interested in GAB-related water management. This workshop was aimed at identifying and documenting key science issues and strategies to fill hydrogeological knowledge gaps that will assist federal and state/territory governments in addressing groundwater management issues within the GAB, such as influencing the development of the next Strategic Management Plan for the GAB. This report summarises the findings out of the workshop.

The East Australian Current (EAC) onshore encroachment drives coastal upwelling and shelf circulations, changes slope-shelf bio-physical dynamics, and consequently exerts significant influence on coastal marine ecosystem along the south-eastern Australian margin. The EAC is a highly dynamic eddy-current system which exhibits high-frequency intrinsic fluctuations and eddy shedding. As a result, low-frequency variability in the EAC is usually overshadowed and rarely detectable. For decades, despite many efforts into the ocean current observations, the seasonality of EAC’s shoreward intrusion remains highly disputable. In this study, for the first time we use a long-term (26 years) remotely sensed AVHRR Sea Surface Temperature (SST) dataset spanning 1992-2018 to map the EAC off the coast of northern New South Wales (NSW), between 28°S - 32.5°S. A Topographic Position Index (TPI) image processing technique was applied to conduct the quantitative mapping. The mapping products have enabled direct measurement (area and distance) of the EAC’s shoreward intrusion. Subsequent spatial and temporal analyses have shown that the EAC move closer to the coast in austral summer and autumn than in austral winter, with the mean distance-to-coast ~6 km shorter and occupying the shelf area ~12% larger. This provides quantitative and direct evidence of the seasonality of the EAC’s shoreward intrusion. Such seasonal migration pattern of the EAC thus provides new insights into the seasonal upwelling and shelf circulations previously observed in this region. As a result, we were able to confirm that the EAC is a driving force of the seasonal ocean dynamics for the northern NSW coast.