AusLAMP is a collaborative national project to cover Australia with long-period magnetotelluric (MT) data in an approximately 55 km spaced array. Signatures from past tectonothermal events can be retained in the lithosphere for hundreds of millions of years when these events deposit conductive mineralogy that is imaged by MT as electrically conductive pathways. MT also images regions of different bulk conductivity and can help to understand the continuation of crustal domains down into the mantle, and address questions on the tectonic evolution of Australia. The AusLAMP data presented here were collected as part of three separate collaborative projects involving several organisations. Geoscience Australia (GA), the Geological Survey of South Australia, the Geological Survey of New South Wales, the Geological Survey of Victoria, and the University of Adelaide all contributed staff and/or funding to collection of AusLAMP data; GA and AuScope contributed instrumentation. The data cover the Paleo-Mesoproterozoic Curnamona Province, the Neoproterozoic Flinders Ranges, and the Cambrian Delamerian Orogen, encompassing eastern South Australia and western New South Wales and western Victoria. This project represents the first electrical resistivity model to image the entire Curnamona Province and most of the onshore extent of the Delamerian Orogen, crossing the geographical state borders between South Australia, New South Wales and Victoria.

<div><strong>Output Type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short Abstract: </strong>We have used new magnetotelluric data collected in the Curnamona Province and Delamerian Orogen to image electrical resistivity structures. Our resistivity model confirms crustal-scale conductive features mapped by AusLAMP models, i.e., the prominent Curnamona Province Conductor and the two Nackara Arc conductors, and resolves them in greater detail. The new model also reveals several apparently continuous arcuate conductors within the lower crust extending from the Eastern Nackara Arc Conductor to Broken Hill, and further into the Delamerian Orogen. In the west, these conductors coincide with the dominant structural grain of the Delamerian Orogen and are interpreted to represent ancient fluid pathways associated with major faults in the area. The eastern conductor diverts from the dominant structural grain in the Grasmere knee zone. The source of this conductor is enigmatic, although possibilities could include complex deformation as the Cambrian convergent margin was deformed in the Delamerian Orogeny, or younger events such as the emplacement of the late-Silurian Allambie Woolshed Granite. The conductive features provide new insights for understanding the geodynamic events and potential mineral systems associated with the transition from Proterozoic Australia in the west to the mostly Phanerozoic Tasmanides in the east. These conductivity anomalies may represent large-scale trans-crustal structures, which can place fundamental control on the spatial distribution and formation of mineral systems in the Curnamona Province and Delamerian Orogen.</div><div><br></div><div><strong>Citation: </strong>Jiang, W., Clark, A., Cheng, Y., Doublier, M., Hitchman, A. & Duan, J., 2024. Unveiling electrical resistivity structures along the undercover Delamerian Orogen, Southeast Australia. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://doi.org/10.26186/149232</div>

<div>Magmatic arcs represent a critical source of modern civilisation’s mineral wealth, with their importance only enhanced by the ongoing global transition to a low-carbon society. The ~830-495 Ma Delamerian Orogen, formed at Australia’s eastern cratonic margin, represents rocks ascribed to rift/passive-margin, convergent margin arc, orogenic, and post-orogenic settings. However, poor exposure has limited exploration activity across much of the orogen, despite demonstrated potential for numerous mineral systems. To address this issue, an orogen-wide zircon Hf-O isotope and trace element survey was performed on 55 magmatic samples to constrain the crustal architecture, evolution, and fertility of the Delamerian Orogen, and in turn map parameters that can be used as a guide to mineral potential. These new data define two broad magmatic episodes at: (1) ~585-480 Ma, related to rift/passive margin, convergent arc, orogenic, and post-orogenic activity (Delamerian Cycle); and (2) magmatism associated with the ~490-320 Ma Lachlan Orogen, with peaks at ~420 Ma (onshore, Tabberabberan Cycle) and ~370 Ma (western Tasmania). Isotopic and geochemical mapping of these events show that the ~585-480 Ma Delamerian Cycle has significant orogen-wide variation in magmatic Hf-O isotopes and oxidation-state, suggesting a spatial variation in the occurrence and type of potential mineral systems. The ~420 Ma magmatic event involved predominantly mantle-like Hf-O and oxidised magmatism, whilst the ~370 Ma magmatism shows opposing features. In general, The potential to host Cu-Au porphyry and VMS mineralisation (e.g., Stavely, Koonenberry) is present, but restricted, whereas signatures favourable for Sn-W granite-hosted systems (e.g., Tasmania), are more common. These new data constrain time-space variations in magma composition that provide a valuable geological framework for mineral system fertility assessments across the Delamerian Orogen. Furthermore, these data and associated maps can used to assess time-space mineral potential and facilitate more effective exploration targeting in this covered region.</div> <b>Citation:</b> Mole, D., Bodorkos, S., Gilmore, P.J., Fraser, G., Jagodzinski, E.A., Cheng, Y., Clark, A.D., Doublier, M., Waltenberg, K., Stern, R.A., Evans, N.J., 2023. Architecture, evolution and fertility of the Delamerian Orogen: Insights from zircon. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, <a href+"https://dx.doi.org/10.26186/148981">https://dx.doi.org/10.26186/148981</a>

<div>The Australian continent comprises a broad dichotomy of crustal settings; from the Archean–Proterozoic cratonic core in the centre and west, to the accretionary margin of the Tasmanides in the east. These continental blocks meet at the Tasman Line, where successive arc systems built the eastern third of Australia in ca. 250 Myrs. This interface represents one of Australia’s most fundamental crustal boundaries and is marked by the ca. 520–490 Ma Delamerian Orogen in south-eastern Australia. Despite its first-order crustal control on tectonism, magmatism, deformation, and mineral systems in the area, the Delamerian Orogen remains poorly understood. Here, we present new zircon Hf-O isotopic and trace element data on 32 samples across the south-east Tasman Line. This initial dataset, which will grow over the next 12 months as part of Geoscience Australia’s Exploring for the Future program, will be used to constrain the time-space crustal architecture and evolution of Australia’s south-eastern Precambrian cratonic margin. These first samples include Paleoarchean to Devonian felsic magmatic rocks from the eastern Gawler Craton, across the Delamerian Orogen, to the Central Lachlan Orogen, and show that the crust of south-east Australia has a significant pre-history, with crustal reworking a major feature across the region. Delamerian arc magmatism appears to have involved significant reworking of Australia’s south-eastern Precambrian margin, as recorded by sub-chondritic Hf-isotope data. Assuming a significant mantle-component in the initial arc magmas, contamination by the ancient overlying continental rocks, some as old as ca. 3250 Ma, resulted in less juvenile compositions. This observation suggests Australia’s south-eastern Gondwanan margin may have consisted of a west-dipping continental arc, rather than an offshore island arc. The ‘heavy’ supracrustal δ18O of magmatic rocks across the area since the Paleoproterozoic is testament to the long-lived terrestrial nature of this continental margin, and its influence on magmatism across >1 billion years of Earth history.&nbsp;</div> This Abstract was submitted/presented to the 2022 Specialist Group in Geochemistry, Mineralogy and Petrology (SGGMP) Conference 7-11 November (https://gsasggmp.wixsite.com/home/biennial-conference-2021)

<div>A multi-disciplinary program of geological and geophysical data collection and integration, focussed on the Delamerian Orogen, was undertaken as part of Geoscience Australia’s Exploring for the Future (EFTF) program and the Mineral Exploration Cooperative Research Centres (MinEx CRC) National Drilling Initiative (NDI).&nbsp;In this study, we integrate learnings from these data with existing geological and geophysical data to refine the basement geology of the Loch Lilly-Kars Belt, Lake Wintlow Belt and Wilcannia High. Our interpretation provides a revised geological framework for a frontier exploration region in the Delamerian Orogen.&nbsp;This product includes ESRI shape files and layer files, accompanying notes, and several appendices containing new detrital zircon U-Pb geochronology data from the map area as well as the broader Delamerian Orogen.</div>

<div>The Delamerian Orogen is a spatially (~1500&nbsp;km long by ~300 km wide) and temporally (ca. 830 to 495 Ma) extensive orogenic system spanning five states in central and eastern Australia. The spatial extent of the orogen was defined by Glen (2005) as the distribution of rocks that underwent their first deformation in the mid-to-late Cambrian Delamerian Orogeny, with the orogen impacted by younger geodynamic events in the Phanerozoic. The orogen is poorly exposed overall and is mostly covered by a series of younger sedimentary basins, volcanic rocks and regolith.</div><div>In the last few years, a multi-disciplinary program of geological and geophysical data collection and integration, focused on the Delamerian Orogen, was undertaken as part of Geoscience Australia’s (GA) Exploring for the Future (EFTF) program and the Mineral Exploration Cooperative Research Centres (MinEx CRC) National Drilling Initiative (NDI). This work program, outlined by Gilmore et al. (2023), compliments the Geological Survey of South Australia’s recent MinEx CRC NDI drilling campaign in the Loch Lilly-Kars Belt in South Australia (Wise, 2023). These efforts have resulted in a greatly increased volume of lithological, geochronological, geochemical, and geophysical datasets, especially in the vicinity of the Loch Lilly-Kars Belt (e.g. Brotodewo et al., 2021; Cheng et al., 2024a; Cheng et al., 2024b; Clark et al., 2024; Curtis, 2022; Doublier et al., 2024; Mole et al., 2024; Pitt et al., 2023; Taylor et al., in prep.; Wise, 2023). Two time-space plots and an accompanying map (appendices A, B and C)&nbsp;have been prepared to convey the geological history of the Delamerian Orogen within the DCD project area on mainland Australia:</div><div><br></div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;An overview time-space plot designed to provide a simplified geological history through the orogen from the Archaean to the present.</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;A detailed time-space plot with three (northern, central and southern) traverses to reflect changes in geological history and stratigraphy along the strike and width of the Delamerian Orogen, focussed on the start of the Ediacaran to the end of the Devonian.</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Location map showing the traverses used in the detailed time-space plot.</div><div>The time-space plots are the first holistic time-space plots for the Delamerian Orogen on mainland Australia. They allow a comparison of the similarities and differences in the age and location of magmatism, sedimentation, deformation and mineralisation across the Delamerian Orogen in New South Wales (NSW), South Australia (SA) and Victoria, at both a high level (overview) and stratigraphic unit level (detailed).</div><div>This record outlines the methodology and data used (Appendix D)&nbsp;to compile the time-space plots.</div><div><br></div>

<div>A keynote talk talk given at Uncover Curnamona 2022 by Angela O'Rourke outlining the rationale, work program and new data acquisition for Geoscience Australia's Darling-Curnamona-Delamerian Project within Exploring for the Future</div> This presentation was given to the 2022 Uncover Curnamona 2022 Conference 31 May - 2 June:<br>(https://www.gsa.org.au/common/Uploaded%20files/Events/Uncover%20Curnamona%202021/UC2022_short_program_A4_web%20(003).pdf)

<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>The Darling-Curnamona-Delamerian (DCD) project focused on the covered portion of the Delamerian orogen, situated in the south-eastern mainland states of Australia.&nbsp;The aims of the project were to develop a greater understanding of the geodynamic history of the Delamerian Orogen, characterise known magmatic-hydrothermal mineral systems, and assess mineral potential for a suite of minerals including copper (Cu), gold (Au), and nickel (Ni), and critical minerals like platinum-group elements (PGEs) and rare-earth elements (REEs). </div><div>Here, we collate whole rock geochemistry data from new and legacy samples of mafic to intermediate magmatic rocks of the Loch Lilly-Kars Belt in order to determine the likely source of these magmas and constrain the prevailing tectonic setting during their emplacement. We apply multi-elemental diagrams and various elemental discrimination diagrams to characterise various groups of magmatic rocks in these belts, taking into account their geographic affinity and new geochronological data (e.g. Mole et al., 2023; Mole et al., 2024). The geochemical characteristics of these groups and the implications for the tectonic setting into which they were emplaced are discussed. Comparisons are made with potentially similar magmatic rocks of the&nbsp;Koonenberry Belt and Grampians-Stavely Zone. Results from this study have significant implications for the tectonic setting in which the Loch Lilly-Kars Belt developed, and hence also the mineral potential of the Belt. </div><div> </div>

<div><strong>Output type: </strong>Exploring for the Future Extended Abstract </div><div><br></div><div><strong>Short Abstract: </strong>The Delamerian Orogen, with a length of ~1000 km on mainland Australia and a proven potential to host mineralisation, represents an evolving exploration opportunity. However, uncertainty surrounding the age and tectonic setting of the orogen is a barrier to confident exploration in frontier covered regions, such as the Loch Lilly-Kars Belt in western New South Wales and South Australia. A major area of uncertainty is the configuration and extent of the Cambrian convergent-margin system and lateral variations thereof. In this study, we highlight multidisciplinary data from new and legacy sources, including lithology, geochronology, geochemistry, potential-field geophysics, deep-crustal seismic, and magnetotelluric data that permit a revised interpretation of the geological framework for the Delamerian Orogen in mainland Australia, with an emphasis on the covered, central part of the system. These data indicate that a largely continuous, east-facing volcanic arc developed in the Delamerian Orogen in the Cambrian. The arc transitions from exhibiting a strong continental affinity in the Koonenberry Belt to having less continental affinity in the Grampians-Stavely Zone of Victoria. The Loch Lilly-Kars Belt is interpreted to have occupied a volcanic arc to incipient back-arc position in the middle Cambrian.&nbsp;</div><div><br></div><div><strong>Citation: </strong>Clark A.D., et al., 2024. Cambrian convergent margin configuration in the Delamerian Orogen of mainland Australia. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://doi.org/10.26186/149647 </div>