<div>Geoscience Australia's geoscientific relational databases use look-up tables to describe the data stored within. These look-ups contain, but are not limited to, information about boreholes, field geology, inorganic and organic geochemistry, hydrochemistry, geophysics, rock properties, samples and other general geological terms. These terms have then been compiled into a vocabulary of terms for publication via GA's vocabulary service. Within this vocabulary, GA references where sourced terms are published in external vocabularies with a source vocabulary URI (Uniform Resource Identifier). </div><div><br></div><div>All vocabularies, collections of concepts within vocabularies and individual concepts are identified with URI persistent identifiers of the form:</div><div>http://pid.geoscience.gov.au/def/voc/ga/{VOCABULARY-KEY}/{COLLECTION-OR-CONCEPT-NAME}</div>

<div>Convergent margins are a hallmark feature of modern style plate tectonics. One expression of their operation is metallogenesis, which therefore may yield important insights into secular changes in styles of convergence and subduction. A global comparison of metallogenesis along convergent margins of over 20 well-endowed provinces indicates a consistent and systematic progression of mineral deposit types. We term this progression the convergent margin metallogenic cycle (CMMC). </div><div> This CMMC mirrors convergent margin evolution. Each metallogenic cycle begins with the formation of porphyry copper deposits and/or volcanic-hosted massive sulphide deposits, associated with arc construction and back arc basin formation, respectively. When the convergent margin transitions into contraction/orogenesis due to processes such as accretion, flattening of subduction, or continent-continent collision, mineral deposits that form include orogenic gold and structurally hosted base metal deposits. Post-contractional extension is marked by the formation of intrusion related rare metal (tin, tungsten, molybdenum) and gold deposits, pegmatites, and alkaline porphyry copper deposits, closing the CMMC. </div><div> Our analysis of the metallogenic record reveals that prior to ~3 Ga, metallogenesis is episodic and non-systematic, with CMMCs not recognised. From the mid- to late Mesoarchean onwards, CMMCs are observed in all provinces analysed, and display systematic trends through time: the Meso- to Neoarchean metallogenic provinces are characterized by a single metallogenic cycle, whereas in the Paleo- to Mesoproterozoic provinces, both single and multiple metallogenic cycles occur. From the middle Neoproterozoic onwards multiple metallogenic cycles are the rule. This evolution is accompanied by an increase in the duration of metallogenesis, ranging from ~100 to 180 million years in the Meso- to Neoarchean and 220 to more than 400 million years since the late Proterozoic.&nbsp;</div><div> We interpret these trends to reflect secular changes in tectonic processes and Earth evolution. The emergence of CMMCs from ~3 Ga provides independent evidence for the operation of some early form of subduction since this time. The fact that CMMCs are recognized in all provinces of mid-Meso- to Neoarchean age suggests that subduction was the common <em>modus operandi</em> rather than an exception. The first appearance of multiple metallogenic cycles in the Paleoproterozoic may reflect the strengthening of cratonic margins by tectonothermal maturation since formation in the Archean. Long-lived metallogenesis and multiple metallogenic cycles in the Neoproterozoic and Phanerozoic are linked to deep-slab break-off, or modern, subduction in which the internal strength of the subducting slab allows maintenance of slab coherency.&nbsp;&nbsp;</div><div> This Abstract was submitted/presented to the 2023 6th International Archean Symposium (6IAS) 25 - 27 July (https://6ias.org/)

Interpretation of 2014–2015 deep crustal seismic reflection and magnetotelluric data has revised the architecture and geodynamic framework of western Queensland, with implications for the assembly and dispersal of the supercontinents Nuna, Rodinia and Gondwana. In the Mount Isa Province, crustal-scale boundaries of the Leichhardt River Domain, Kalkadoon-Leichhardt Domain and Eastern Subprovince are mapped in the third dimension. The Leichhardt River and Kalkadoon-Leichhardt domains have similar Nd isotopic T 2DM model ages to provinces to the west, indicating they were part of ancestral North Australian Craton (NAC); the Eastern Subprovince is a separate terrane, with the Pilgrim Fault a collisional suture. The Gidyea Suture Zone separates the Mount Isa Province from the subsurface Numil Seismic Province. To the east, the west-dipping Yappar Fault separates east-dipping structures in the west from west-dipping structures in the east, forming a classic doubly vergent orogen within the upper plate of a convergent margin. The northwestern boundary of the Bernfels Seismic Province, the Kynuna Fault, truncates the Gidyea Suture Zone, implying this seismic province was welded to the NAC prior to initial deposition of the Etheridge Province. The Cork Fault truncates the north-south grain of the Mount Isa Province; the easternmost part of the NAC has been excised, presumably during breakup of Nuna. The subsurface Brighton Downs Seismic Province, formerly part of the northern Thomson Orogen, is a discrete seismic province, located between the NAC and the Thomson Orogen, and welded to the NAC during the accretion of Rodinia. Basement to the Thomson Orogen is a collage of microplates, accreted to the Brighton Downs Seismic Province during the assembly of Gondwana. By 530 Ma, eastern Australia faced an open Pacific Ocean, with the Thomson Orogen in a backarc setting. Thus, northeastern Australia contains a record of repeated continental accretion and breakup over at least three supercontinent cycles. <b>Citation: </b>Russell J. Korsch, Michael P. Doublier, Dominic D. Brown, Janelle M. Simpson, Andrew J. Cross, Ross D. Costelloe, Wenping Jiang, Crustal architecture and tectonic development of western Queensland, Australia, based on deep seismic reflection profiling: Implications for Proterozoic continental assembly and dispersal, <i>Tectonophysics</i>, Volume 878, 2024, 230302, ISSN 0040-1951, https://doi.org/10.1016/j.tecto.2024.230302.

Geoscience Australia has undertaken a regional seismic mapping study of the offshore Otway Basin extending across the explored inner basin to the frontier deep-water region. Seismic interpretation covers over 18,000 line-km of new and reprocessed data acquired in the 2020 Otway Basin seismic program, over 40,000 line-km of legacy 2D seismic data and GA’s new 2023 Otway 3D post-stack Mega Merge seismic dataset. This work provides a new perspective on regional structural architecture and basin evolution and has important implications for hydrocarbon prospectivity of this region. This seminar was two short talks centring on the Otway Basin. <u>Post-stack 3D merging to fast-track regional interpretation - offshore Otway Basin case study, presented by Merrie-Ellen Gunning</u> This case study was to produce a regularised and seamless 3D dataset of the highest possible quality, for the offshore Otway Basin, within two-months. The input migrated volumes varied by data extent, migration methodology, angle range and grid orientation. Fourteen input volumes totalling 8,092 km2 were post-stack merged and processed to produce a continuous and consistent volume, enabling more efficient and effective interpretation of the region. The surveys were regularised onto a common grid, optimised for structural trend, prior to survey matching. A mis-tie analysis algorithm, applied over a time window optimised for interpretation of key events, was used to derive corrections for timing, phase and amplitude, using a reference. This was followed by time-variant spectral and amplitude matching to improve continuity between volumes. Additional enhancements including noise removal and lateral amplitude scaling were also applied. The final merged volume offers significant uplift over the inputs, providing better imaging of structure and events and dramatically improving the efficiency and quality of interpretation. This enables rapid reconnaissance of the area by explorers. <u>Structural architecture of the offshore Otway Basin presented by Chris Nicholson</u> We present new basin-scale isochore maps that show the distribution of the Cretaceous depocentres. Maps for the Lower Cretaceous Crayfish and Eumeralla supersequences, together with those recently published for the Upper Cretaceous Shipwreck and Sherbrook Supersequences, completes the set of isochore maps for the main tectonostratigraphic basin intervals. Mapping of basement involved faults has revealed structural fabrics that have influenced depocentre development. The tectonostratigraphic development of depocentres and maps of deep crustal units delineate crustal thinning trends related to late Cretaceous extension phases. This work highlights the need to review and update structural elements. For example, the boundary between the Otway and Sorell basins is now geologically constrained. The refinements to the tectonostratigraphic evolution of the Otway Basin presented here have important implications for the distribution and potential maturity of petroleum systems, especially with regard to heat flow associated with crustal extension.

Following deep seismic reflection surveys on the Yilgarn and Pilbara cratons by Geoscience Australia with the Geological Survey of Western Australia and on the Superior Craton by the Canadian Lithoprobe program, these cratons are now some of the best surveyed Archean regions on Earth. We present seismic images that highlight how variations in crustal architecture relate to differences in Archean tectonic processes between cratons. All cratons are characterized by a mostly non-reflective 4–12 km-thick uppermost crust due to the presence of large granitoid plutons and gneissic domains. Localized regions of upper crustal seismic reflectivity are typically interpreted as supracrustal rocks and mafic sills or faults and shear zones. The middle and lower Archean crust contains variably complex geometries of relatively high amplitude reflections, though in some regions, such as the Eastern Goldfields Superterrane and the Abitibi Greenstone Belt, the lower crust appears less reflective than the middle crust. Crustal thicknesses vary from 30 km in the eastern Pilbara to 35–40 km across much of the Yilgarn and Superior, though thicknesses as great as 45–52 km occur locally in the latter two cratons. The characteristics of the Archean crust-mantle boundary, or Moho, which is commonly well-defined, differs between cratons, indicating significant variations in the tectonic processes that have driven the final stages of crustal evolution. Dipping reflections in the uppermost mantle linked to convergent crustal structures are interpreted as relict subduction scars. In the southern Superior Craton, Moho offsets and northdipping reflections in the middle and lower crust arose through successive underthrusting of Meso-Neoarchean island arcs, oceanic plateaux and microcontinental fragments, as they accreted against a pre-existing northern nucleus (e.g. North Caribou and Opatica terranes). Seismic reflection lines reveal a doubly vergent orogen above north-dipping mantle reflections that indicate subduction drive accretion. Post-orogenic crustal extension, which is inferred from crustal-scale normal shear zones and dropped greenstone belts, has not erased the original accretionary crustal architecture. In contrast, in the Yilgarn Craton interior, accretionary structures are less clear and there are no prominent offsets in the Moho. In the Youanmi Terrane, which represents the cratonic nucleus, a pervasive fabric of listric east-dipping mid-crustal reflections soles out into the upper part of subhorizontal lower crustal reflections. We interpret this reflective fabric to be the result of widespread crustal collapse during the late stage of craton evolution at c. 2.65–2.6 Ga that also produced subsidence of the upper crust. Though terrane boundaries can be identified in seismic data across the Eastern Goldfields Superterrane, these boundaries have commonly been modified by extension, which also overprinted any accretionary lower crustal structures, perhaps simultaneous with widespread intrusion of post-tectonic melts. Exhumation of moderately reflective, amphibolite to granulite facies crust in the Narryer Terrane above dipping mantle reflectors indicates that shortening along the northwestern edge of the Yilgarn Craton was subduction driven. In the eastern Pilbara Craton, shallowly dipping to subhorizontal reflections in the middle and lower crust preclude crustal-scale vertical tectonic movements and imply that the vertical displacements inferred from surface mapping were largely confined to the upper crust. <div>The abstract accompanies a talk the describes the architecture and and related tectonic processes of several Archean cratons based on reflection seismic interpretations. </div> This Abstract was submitted to & presented at the 2023 6th International Archean Symposium (6IAS) 25 - 27 July (https://6ias.org/)

Geoscience Australia has undertaken a regional seismic mapping study of the offshore Otway Basin extending across the explored inner basin to the frontier deep-water region. Seismic interpretation covers over 18000 line-km of new and reprocessed data acquired in the 2020 Otway Basin seismic program and over 40000 line-km of legacy 2D seismic data. We present new basin-scale isochore maps that show the distribution of the Cretaceous depocentres. Maps for the Lower Cretaceous Crayfish and Eumeralla supersequences, together with those recently published for the Upper Cretaceous Shipwreck and Sherbrook Supersequences, completes the set of isochore maps for the main tectonostratigraphic basin intervals. Mapping of basement involved faults has revealed structural fabrics that have influenced depocentre development. The tectonostratigraphic development of depocentres and maps of deep crustal units delineate crustal thinning trends related to late Cretaceous extension phases. This work highlights the need to review and update structural elements. For example, the boundary between the Otway and Sorell basins is now geologically constrained. The refinements to the tectonostratigraphic evolution of the Otway Basin presented here have important implications for the distribution and potential maturity of petroleum systems, especially with regard to heat flow associated with crustal extension. Presented at the 2024 Australian Energy Producers Conference & Exhibition (AEP) (https://energyproducersconference.au/conference/)

<div>The city of Lae is Papua New Guinea (PNG)’s second largest, and is the home of PNG’s largest port. Here, a convergence rate of ~50 mm/yr between the South Bismarck Plate and the Australian Plate is accommodated across the Ramu-Markham Fault Zone (RMFZ). The active structures of the RMFZ are relatively closely spaced to the west of Lae. However, the fault zone bifurcates immediately west of the Lae urban area, with one strand continuing to the east, and a second strand trending southeast through Lae City and connecting to the Markham Trench within the Huon Gulf. </div><div>The geomorphology of the Lae region relates to the interaction between riverine (and limited marine) deposition and erosion, and range-building over low-angle thrust faults of the RMFZ. Flights of river terraces imply repeated tectonic uplift events; dating of these terraces will constrain the timing of past earthquakes and associated recurrence intervals. Terrace riser heights are typically on the order of 3 m, indicating causative earthquake events of greater than magnitude 7. </div><div>Future work will expose the most recently active fault traces in trenches to assess single event displacements, and extend the study to the RMFZ north of Nadzab Airport. These results will inform a seismic hazard and risk assessment for Lae city and surrounding region.</div> Presented at the 2023 Australian Earthquake Engineering Society (AEES) Conference

<div><strong>Output type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short abstract: </strong> Crustal architecture provides first order controls on the distribution of mineral resources of an area and is best imaged by deep seismic reflection data. Here we present a first interpretation of seismic line 22GA-CD2, acquired as part of the Darling-Curnamona-Delamerian (DCD) project. Line 22GA-CD2 images the central eastern Delamerian Orogen, where basement rocks are concealed by the Murray Basin. Key findings include: (i) the crustal architecture preserves many characteristics of the early evolution of west-dipping Delamerian subduction, accretion and orogeny between ~ 515 Ma - 495 Ma. This initial configuration has been reworked and reactivated during younger orogenic events; (ii) the lower and middle crust constitutes the newly defined Barrier Seismic Province, which is also imaged in legacy seismic reflection line 05GA-TL1 and interpreted to continue northeast to the Olepoloko Fault; (iii) a similar seismic character to that of the Barrier Seismic Province has been observed in legacy seismic reflection lines in Victoria and related to a Cambrian accretionary setting and adjacent foreland; (iv) the present-day upper crustal configuration is largely the result of contractional fault reactivation, with significant vertical movements during the Kanimblan-Alice Springs Orogeny (~ 360 Ma - 340 Ma); (v) a large area of prospective rocks for mineral deposits with Cambrian arc-affiliation are accessible to exploration under shallow cover of the Murray Basin (often less than 200 m).</div><div>&nbsp;&nbsp;</div><div><strong>Citation: </strong>Doublier M.P., et al., 2024. Crustal architecture along seismic line 22GA-CD2: new insights from the Darling-Curnamona-Delamerian deep seismic reflection survey. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://dx.doi.org/10.26186/149658</div>

<div>In Australia, wide-spread sedimentary basin and regolith cover presents a key challenge to explorers, environmental managers and decision-makers, as it obscures underlying rocks of interest. To address this, a national coverage of airborne electromagnetics (AEM) with a 20&nbsp;km line-spacing is being acquired. This survey is acquired as part of the Exploring for the Future program and in collaboration with state and territory geological surveys. This survey presents an opportunity for regional geological interpretations on the modelled AEM data, helping constrain the characteristics of the near-surface geology beneath the abundant cover, to a depth of up to ~500&nbsp;m.</div><div> The AEM conductivity sections were used to delineate key chronostratigraphic boundaries, e.g. the bases of geological eras, and provide a first-pass interpretation of the subsurface geology. The interpretation was conducted with a high level of data integration with boreholes, potential fields geophysics, seismic, surface geology maps and solid geology maps. This approach led to the construction of well-informed geological interpretations and provided a platform for ongoing quality assurance and quality control of the interpretations and supporting datasets. These interpretations are delivered across various platforms in multidimensional non-proprietary open formats, and have been formatted for direct upload to Geoscience Australia’s (GA) Estimates of Geological and Geophysical Surfaces (EGGS) database, the national repository of multidisciplinary subsurface depth estimates.</div><div> These interpretations have resulted in significant advancements in our understanding of Australia’s near-surface geoscience, by revealing valuable information about the thickness and composition of the extensive cover, as well as the composition, structure and distribution of underlying rocks. Current interpretation coverage is ~110,000 line kilometres of AEM conductivity sections, or an area &gt;2,000,000&nbsp;km2, similar to the area of Greenland or Saudi Arabia. This ongoing work has led to the production of almost 600,000 depth estimate points, each attributed with interpretation-specific metadata. Three-dimensional line work and over 300,000 points are currently available for visualisation, integration and download through the GA Portal, or for download through GA’s eCat electronic catalogue. </div><div> These interpretations demonstrate the benefits of acquiring broadly-spaced AEM surveys. Interpretations derived from these surveys are important in supporting regional environmental management, resource exploration, hazard mapping, and stratigraphic unit certainty quantification. Delivered as precompetitive data, these interpretations provide users in academia, government and industry with a multidisciplinary tool for a wide range of investigations, and as a basis for further geoscientific studies.</div> Abstract submitted and presented at 2023 Australian Earth Science Convention (AESC), Perth WA (https://2023.aegc.com.au/)

<div>The active seismic and passive seismic database contains metadata about Australian land seismic surveys acquired by Geoscience Australia and its collaborative partners. </div><div>For active seismic this is onshore surveys with metadata including survey header data, line location and positional information, and the energy source type and parameters used to acquire the seismic line data. For passive seismic this metadata includes information about station name and location, start and end dates, operators and instruments. Each also contains a field that contains links to the published data. </div><div><br></div><div>The active and passive seismic database is a subset of tables within the larger Geophysical Surveys and Datasets Database and development of these databases was completed as part of the second phase of the Exploring for the Future (EFTF) program (2020-2024). The resource is accessible via the Geoscience Australia Portal&nbsp;(https://portal.ga.gov.au/), under 'Geophysics'. Use 'active seismic' or 'passive seismic' as search terms. </div><div><br></div>