<div>Ideally when combining different 3D seismic surveys differences in acquisition parameters warrant full pre-stack reprocessing from field data. However, there are occasions where this is not possible due to time, financial or data access constraints; a valuable alternative is post-stack merging and enhancement of existing migrations. The offshore Otway Basin was the subject of such a project, the objective of which was to produce a regularised and seamless 3D dataset of the highest possible quality, within a two-month turnaround time. The input migrated volumes varied by data extent, migration methodology, angle range and grid orientation. 14 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. DUG’s mis-tie analysis algorithm, applied over a time window optimised for interpretation of key</div><div>events, was used to derive corrections for timing, phase and amplitude, using the Investigator North survey as a reference. This was followed by time-variant spectral and amplitude matching, with gain corrections applied, 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 event and dramatically improving the efficiency and quality of interpretation. This enables rapid reconnaissance of the area by explorers. Presented at the Australian Energy Producers (AEP) Conference & Exhibition

<div>The Central Australian Basins 2D Seismic Reprocessing Project is an initiative under Geoscience Australia's "Australia’s Future Energy Resources" (AFER) program, funded by the Australian Government through the "Exploring for the Future" (EFTF) program. The project aims to assess the untapped resource potential of selected underexplored onshore sedimentary basins in terms of natural gas, oil, and groundwater, while also investigating opportunities for geological storage of carbon dioxide and hydrogen. By providing pre-competitive data, the initiative seeks to stimulate investment in mineral, energy, and groundwater exploration.</div><div>&nbsp;</div><div>This project focuses on improving the understanding of the geological evolution and relationships among various Australian basins, ranging from the early Paleozoic Amadeus, Warburton and Adavale basins to the Permian-Triassic Pedirka, Simpson, northern Cooper and southern Galilee basins, and the Jurassic–Cretaceous western Eromanga Basin. To achieve this, modern seismic processing techniques were applied to 33 selected multi-vintage legacy lines with a total length of approximately 2,100 km, enhancing the resolution and image quality of the seismic lines. The dataset includes deep crustal as well as shallow lines from Queensland and South Australia. The data were collected using various acquisition sources such as Vibroseis, Geoflex, and dynamite. Six merged lines were also created to aid in interpretation.</div><div>&nbsp;</div><div>Both stacks and gather data are provided in SEG-Y format, along with navigation data, velocity, and statics. The reprocessing focused on enhancing seismic reflectors and faults, attenuating noise, and optimising frequency content for target depths. Techniques used in the reprocessing include creating a 3D static model, noise attenuation methods, minimum phasing of the Vibroseis data to match dynamite lines, surface-consistent deconvolution, and building a precise velocity model for optimising pre-stack time and depth migration.</div><div><br></div><div><strong>Processed gather data&nbsp;for this survey are also available on request from clientservices@ga.gov.au - Quote eCat# 148931</strong></div>

<div><strong>Output type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short Abstract: </strong>Seismic tomography has been used for more than 50 years to map the seismic velocity structure of Earth’s interior. Here, we use data from the Exploring for the Future program, AusArray 2o deployment, to perform ambient noise tomography of the Australian continent. In this approach, stacks of cross-correlations of background seismic noise recorded by pairs of seismometers are employed to extract an approximation to the surface wave trains travelling between the seismometers. We have developed a semi-automatic approach to estimate dispersion properties of surface waves as a function of frequency at 0.01 – 1 Hz and deployed the largest ever network of broadband seismometers across the country to image the continental crust of Australia. In this study, we present an ambient noise tomography map of the Australian continent at 0.4 Hz (2.5 seconds), which is sensitive to the top 3 km of the Earth’s crust. Our model shows improved resolution across the country, for example, we observed a large low-velocity anomaly (~2.5 km/s) which delineates the shape of the entire Caning basin in Western Australia. This basin has never been imaged at this detail before, as previous tomographic studies do not measure surface wave velocity up to 0.4 Hz and do not have stations deployed in this area. The outcome demonstrates the utility of the ambient noise tomography method of imaging first-order features, that could be built upon for resource potential assessments.</div><div><br></div><div><strong>Citation: </strong>Hejrani B., Hassan R., Gorbatov A. & Zhao J., 2024. Towards continental-scale ambient noise tomography of Australia: a preliminary result from AusArray data. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://doi.org/10.26186/149637</div>

<div>The architecture of the lithosphere controls the distribution of thermal, compositional and rheological interfaces. It therefore plays a fundamental role in modulating key ore-forming processes including the generation, transport, fractionation, and contamination of melts.&nbsp;Recognition of its importance has led to renewed efforts in recent years to incorporate constraints on lithospheric structure into the targeting of prospective regions for mineral exploration. One example is a suggested relationship between the genesis of porphyry copper deposits – known to be associated with evolved, silica-rich magmas – and the thickness of the crust.&nbsp;Here, using a new compilation of spot measurements, we explore the utility of crustal thickness as an exploration tool for porphyry copper deposits.</div> This Abstract was submitted & presented at the 2022 American Geophysical Union (AGU) Fall Meeting 12-16 December (https://www.agu.org/Fall-Meeting-2022)

<div>The Australian Government’s Data Driven Discoveries program has reprocessed 60 selected multi-era legacy seismic lines, covering approximately 2,520 km across the Adavale Basin, south-central Queensland. Reprocessing of legacy seismic data from the Adavale Basin aims to create a modern, consistent and integrated seismic dataset that provides new insights into the geological structure of the basin and deepens our understanding of the basin’s minerals, energy, underground storage and groundwater potential.</div><div><br></div><div>The reprocessed lines were chosen to tie into 5 wells that were previously sampled for chemostratigraphic analysis through the Data Driven Discoveries program (Riley et al., 2023, eCat 147773), including Allendale 1, Boree 1, Gilmore 1, Quilberry 1 and Stafford 1. The Adavale Basin 2D Reprocessed Seismic Data Package also complements new deep crustal seismic data being acquired in the Adavale Basin by the program.</div><div><br></div><div>The reprocessing workflow prioritised enhancing the image quality of the selected legacy seismic lines, reducing noise, and fine-tuning frequency content for specific target depths. Techniques employed included creating a 3D static model, applying noise attenuation methods, surface-consistent deconvolution, and constructing an accurate velocity model to optimise pre-stack time and depth migration. </div><div><br></div><div>Both stacks and gather data are provided in SEG-Y format, along with navigation data, velocity, and statics.</div><div><strong>&nbsp;</strong></div><div><strong>Processed gather data for this survey are available on request from clientservices@ga.gov.au - Quote eCat# 149018</strong></div>

<div>The ‘Major crustal boundaries of Australia’ dataset synthesises more than 40 years of acquisition of deep seismic reflection data across Australia, where major crustal-scale breaks, often inferred to be relict sutures between different crustal blocks, have been interpreted in the seismic reflection profiles. The widespread coverage of the seismic profiles now provides the opportunity to construct a map of major crustal boundaries across Australia. Starting with the locations of the crustal breaks identified in the seismic profiles, geological (e.g. outcrop mapping, drill hole, geochronology, isotope) and geophysical (e.g. gravity, aeromagnetic, magnetotelluric, passive seismic) data are used to map the crustal boundaries, in map view, away from the seismic profiles. For some of these boundaries, a high level of confidence can be placed on the location, whereas the location of other boundaries can only be considered to have medium or low confidence. In other areas, especially in regions covered by thick sedimentary successions, the locations of some crustal boundaries are essentially unconstrained. </div><div>The ‘3D Major Crustal Boundaries Model – 2024 Edition’, utilising the corresponding ‘Major crustal boundaries of Australia – 2024 Edition’ 2D geographic information system (GIS) dataset (Doublier and Korsch, 2024), shows the locations and geometries of inferred ancient plate boundaries in three dimensions, providing constraints on the crustal architecture of Australia. It allows a better understanding of how the Australian continent was constructed from the Mesoarchean through to the Phanerozoic, and how this evolution and these boundaries have controlled metallogenesis. It is best viewed as a dynamic dataset, which will need to be refined and updated as new information, such as new seismic reflection data, becomes available.</div><div><br></div>

<div>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.&nbsp;&nbsp;Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government.</div><div><br></div><div>The Proterozoic Birrindudu Basin is an underexplored region that contains sparse geological data. Strata of similar age are highly prospective to the east, in the McArthur and South Nicholson basins and the Mount Isa region. To investigate this underexplored and data-poor region, the L214 Northwest Northern Territory Seismic Survey was acquired in August to September 2023 by GA and co-funded by the Northern Territory Government. Prior to this survey the region contained minimal seismic data. To complement the acquisition of the seismic survey, a sampling program of legacy stratigraphic and mineral exploration drill holes was also undertaken.</div><div><br></div><div>The new sampling program and seismic reflection data acquired over the Birrindudu Basin and its flanks, has identified many areas of exploration opportunity. This has almost tripled seismic coverage over the Birrindudu Basin, which has enabled new perspectives to be gained on its geology and relationship to surrounding regions. The new seismic has shown an increase in the extent of the Birrindudu Basin, revealing the presence of extensive concealed Birrindudu Basin sedimentary sequences and major, well preserved depocentres. In the central Birrindudu Basin and Tanami Region, shallow basement and deep-seated faults are encouraging for mineralisation, as these structures have the potential to focus mineralised fluids to the near surface. The clear presence of shallow Tanami Region rocks underlying the southern Birrindudu Basin sequences at the northern end of line 23GA-NT2 extends the mineral resource potential of the Tanami Region further north into the southern Birrindudu Basin. A new minimum age of 1822±7 Ma for the deposition of metasediments in drill hole LBD2 for rocks underlying the central Birrindudu Basin, extends the age-equivalent mineral-rich basement rocks of the Tanami Region north into the central Birrindudu Basin – extending the mineral resource potential into a new region.</div><div><br></div><div>The continuous stratigraphy imaged of the Birrindudu Basin by the new seismic is encouraging for energy prospectivity, as the system elements needed for an effective petroleum system, better defined by the new sampling program results, have been imaged to extend over a wider and deeper area. New organic petrological analysis and reflectance data indicate the sampled sections have reached thermal maturity suitable for hydrocarbon generation. Oil inclusion analyses provide evidence for oil generation and migration, and hence elements of a petroleum system are present in the central and northwestern Birrindudu Basin. With the expanded breadth of these rocks demonstrated on the seismic, this greatly increases the spatial extent of hydrocarbon prospectivity in Birrindudu Basin.</div>

<div><strong>Output type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short abstract: </strong>Australia's crust is blanketed by sedimentary cover. Knowledge of the distribution and thickness of sediments is crucial for assessing resource potential. Excellent constraints on sedimentary thickness can be obtained from borehole drilling or active seismic surveys, but these are expensive and often impractical in much of inland Australia. Recently, a relatively simple and low-cost method for estimating the sedimentary thickness using passive seismic data was developed and applied to seismic stations in South Australia. First-order estimates of the thickness of sediments are predicted from the delay time of the Ps converted phase generated at the sediment-basement interface via an empirical relationship constructed using borehole stratigraphy data. Here we expand the analysis to over 1500 seismic stations across Australia, covering numerous sedimentary basins that span the entire range of sedimentary basin ages from Precambrian to present-day. The new results clearly match the broad pattern of expected sedimentation based on the various Australian geological provinces. Using a new compilation of borehole data, we obtain a new, continent-wide empirical relationship from passive seismic delay to sediment cover thickness, offering a fast, simple and cheap way to characterise sediment thickness in under-explored areas. We apply the new relationship to the Exploring for the Future AusArray 2ºx2º data. </div><div><br></div><div><strong>Citation: </strong>Marignier, A., Eakin, C.M., Hejrani, B., Agrawal, S. & Hassan, R., 2024. Australian sedimentary thickness from passive seismic methods. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts. Geoscience Australia, Canberra. https://doi.org/10.26186/149319</div>

<div>Lithospheric structure and composition have direct relevance for our understanding of mineral prospectivity. Aspects of the lithosphere can be imaged using geophysical inversion or analysed from exhumed samples at the surface of the Earth, but it is a challenge to ensure consistency between competing models and datasets. The LitMod platform provides a probabilistic inversion framework that uses geology as the fabric to unify multiple geophysical techniques and incorporates a priori geochemical information. Here, we present results from the application of LitMod to the Australian continent. The rasters summarise the results and performance of a Markov-chain Monte Carlo sampling from the posterior model space. Release FR23 is developed using primary-mode Rayleigh phase velocity grids adapted from Fishwick & Rawlinson (2012).</div><div><br></div><div>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 a low emissions economy, strong 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.</div>

<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>