• Vertical datums are a foundational piece of the positioning puzzle that allows us make sense of height measurements - they make it possible to align height data by defining where all heights are zero. But when the vertical datum is unreliable, we lose perspective on which direction is down and this can cause strange things to happen. Water can appear to flow in the wrong direction or pool in unexpected places. • The Australian Height Datum (AHD) is the current, official, vertical datum in use in Australia. At 50 years old this year, it has stood the test of time well. But, it has a number of bumps and wrinkles (errors and distortions), relies on degrading physical infrastructure and was never intended to be used with modern positioning technology like GPS. The Australian Vertical Working Surface is a shiny new alternative vertical datum that doesn’t depend on any physical infrastructure, is free from the errors in the AHD and is designed to be directly compatible with GPS technology in the first instance.

Studies of three global sediment-hosted zinc provinces (Mt Isa, Australia; Northern Cordillera, Canada/USA; Irish Midlands, Ireland) indicate that deposits in all three provinces are associated with gradients in many geological parameters. These include lead isotopes, the depth of the lithosphere-asthenosphere boundary, upward-continued gravity and magnetotellurics data. These gradients are interpreted to mark major cratonic boundaries, or edges, that control the distribution of these deposits in space and in time. Studies of the Mt Isa Province indicate that regional alteration has caused extensive loss of zinc, copper and cobalt, potentially providing more than sufficient metal for the known deposits. Moreover, in some cases, metal loss corresponds to changes in rock properties, possibly enabling regional mapping of zones of metal loss using geophysical data.

The magnetotellurics (MT) method maps the electrical conductivity/resistivity structure of the subsurface, which provides crucial information for mineral exploration. Geoscience Australia has actively applied the method to provide multiscale world-leading datasets to improve the understanding of geology and resource potential. We demonstrate the value of scaled MT data acquisition starting from mapping large-scale conductivity structures in the lithosphere utilising long-period MT datasets through to the resolution of finer scale structures in the crust suitable for camp scale targeting. Integration of data from multiscale surveys provides an effective way to narrow the search space and to identify ‘targets’ of mineral potential in covered terranes. Our work has helped to increase explorers’ investment confidence for new mineral discoveries in greenfield regions.

Every day, humanity benefits from geodesy. Geodesy is the science of measuring the size, shape, orientation and gravity field of our planet and it is a foundation for evidence-based policies, decisions and program delivery. Geodesy is used every day, in the fields of civil engineering, industrial automation, agriculture, construction, mining, financial transactions, intelligent transport systems, disaster response and emergency management, environmental studies and scientific research. Furthermore, geodesy enables accurate collection, management and alignment of nationally integrated geospatial information – a key requirement for societal, environmental and economic activities, the measuring and monitoring of progress of the 2030 Agenda for Sustainable Development, the Sendai Framework for Disaster Risk Reduction, the Small Island Developing States Accelerated Modalities of Action (SAMOA) Pathway, and other global, regional and national development agenda and initiatives.

The AusAEM survey is the world's largest airborne electromagnetic (AEM) survey flown to date, extending across an area exceeding 3.5 million km2 over Western Australia, the Northern Territory, Queensland, New South Wales Victoria and South Australia. Airborne electromagnetics is a geophysical method at the forefront in addressing the challenge of exploration under cover. In collaboration with the state and territory geological surveys, Geoscience Australia has led a national initiative whose goal is to acquire AEM data at a nominal line spacing of 20 km across Australia. The interpreted AEM conductivity sections were inverted using Geoscience Australia's open source Layered Earth Inversion Sample-By-Sample Time Domain Electromagnetics (GALEISBSTDEM) inversion. Horizontal along-flight line resolution is 12.5 m, and the vertical resolution varies exponentially with depth. Inversion cell sizes increase from 4.0 m at the surface to ~55 m in the bottom cell of the conductivity sections, ~500 m below surface. Consequently, the ability to resolve fine detail varies with depth. Using this dataset, we interpret the depth to chronostratigraphic surfaces, assembled stratigraphic relationship information, and delineated structural and electrically conductive features. Our results improved understanding of upper-crustal geology, led to 3D mapping of palaeovalleys, prompted further investigation of electrical conductors and their relationship to structural features and mineralisation, and helped us continuously connect correlative outcropping units separated by up to hundreds of kilometres. Our interpretation is designed to improve targeting and outcomes for mineral, energy and groundwater exploration, and contributes to our understanding of the chronostratigraphic, structural and upper-crustal evolution of northern Australia. Almost 200,000 regional depth measurements have been collected, each attributed with detailed geological information, are an important step towards a national geological framework, and offer a regional context for more detailed, smaller-scale AEM surveys. The AusAEM programme delivers much more than just reliable depth-to-cover estimates and the location of paleochannels. It can reveal basin architecture and regionally map structures, making it a crucial layer of data for mineral, energy and groundwater and exploration. It has become an essential part of data-driven decision making for conservation and environmental management.

This seminar will showcase new results from the late Carboniferous to Middle Triassic Cooper Basin that challenge existing notions on its evolution, new insights on sediment dispersal pathways and consequently its resource potential. Topics that will be explored include how the Cooper Basin is similar to other failed rift basins and how depositional facies between each of the half-grabens/troughs are influenced by the relationship between sediment supply and the rate of creation of accommodation. Of note are new precise dates and carbon isotope data from the thick coals of the Patchawarra Formation suggesting prolonged and uninterrupted peat accumulation for millions of years during the latter stages of the late Palaeozoic ice age – no modern analogue exists to compare the conditions and longevity of these ancient mires. Come along to the talk to learn more about the Cooper Basin.

The Australian Government, through the National Water Infrastructure Development Fund, commissioned Geoscience Australia to undertake a 3-year project ‘Assessing the Status of Groundwater in the Great Artesian Basin’. The overall aim of the project was to analyse existing and new geoscientific data acquired by the project to improve understanding of the hydrogeological system and water balance in the GAB. In conjunction, the project assessed satellite based technologies for monitoring groundwater storage and level change. This talk will discuss some of the key results of the project. These include: an updated hydrogeological framework for the GAB, mapping aquifer and aquitard properties, geometry and extent; revised groundwater recharge rate estimates in the eastern GAB groundwater intake beds; new groundwater system conceptual models of groundwater recharge processes and groundwater flow; an assessment of the Gravity Recovery and Climate Experiment (GRACE) satellite derived groundwater storage change estimates for the GAB; and Interferometric Synthetic Aperture Radar (InSAR) satellite data, for detecting changes in groundwater levels.

From minerals to meteorites, this presentation will delve into the amazing specimens held at the National Mineral & Fossil Collection, explore our recent work and projects, and identify our diverse stakeholders that we interact with as part of our goals of custodianship, education, outreach, and research support. The National Mineral & Fossil Collection houses world-class mineral, meteorite, fossil, and rock thin-section specimens. The collection is of scientific, historic, aesthetic, and social significance. Geoscience Australia is responsible for the management and preservation of the collection, as well as facilitating access to the collection for research, geoscience education, and public engagement. The collection contains an impressive: • 20,000 gem, mineral and meteorite specimens from localities in Australia and across the globe. • 45,000 published palaeontological specimens contained in the Commonwealth Palaeontological Collection (CPC). • 1,000,000 unpublished fossils in a ‘Bulk Fossil’ collection. • 100,000 rock thin section slides. • 200 historical geoscience instruments including, cartography, geophysical, and laboratory equipment.

Through Commonwealth and State/Territory government partnerships, the National Location Information (NLI) Branch implements cutting-edge approaches to integrate and deliver data, services and analytical capability to the public, Government and critical industries. This DGAL will present examples of NLI’s work - work central to the Australian Government’s ambitious Digital Economy Strategy to make Australia a leading global digital economy by 2030, along with the Australian Data Strategy, to ensure government data is in the ‘best state’ to feed this future digital economy. Specifically, the talk will cover: The Digital Atlas of Australia Improving geospatial data and services discovery, share and access The Australian low-water coastline Bringing historic aerial imagery archive back to life ELVIS portal – creating sustainable access through collaboration

Australia's coastline is exposed to tsunamis generated by large subduction earthquakes in the Indian and Pacific Oceans. While recent events had limited impacts in Australia, future earthquakes could in-principle direct much larger waves to our coast. With only a few hours between earthquake detection and tsunami arrival, prior planning is necessary to guide the emergency response. To this end we need an understanding of tsunami hazards: which coastal areas might be inundated, how deep, and how likely? This talk will discuss recent progress in tsunami inundation hazard assessment at Geoscience Australia. We adopt a probabilistic approach to the problem, which involves modelling hypothetical earthquake-tsunamis from major Indian and Pacific Ocean sources, their effects onshore, and their (uncertain) chance of occurrence. To illuminate the science underlying this we will consider: 1. How well tsunami models can simulate historical tsunamis; 2. Representations of hypothetical tsunamis and their natural variability; 3. New techniques to compute onshore hazards while accounting for uncertain earthquake frequencies.