Australia as it exists today is a product of geological processes that have occurred over its 4.5 billion year history. Isotopic studies are one approach to understanding the history and evolution of the Australian continent. Isotope geochronology tells us about the timing of a wide range of geological processes like crystallisation, deformation and cooling of rocks. Isotope geochemistry informs on the precursor components from which the rocks formed, and can act as 'paleogeophysical' sensors to tell us more about the subsurface. The Isotopic Atlas of Australia brings together five of the most widely used isotopic systems in geology and delivers publicly available maps and datasets in a consistent format. This work is unlocking the collective value of decades of investment in data collection, and facilitating qualitative and quantitative comparison and integration with other datasets such as geophysical images. This talk will be an introduction to the world of isotopes as applied to understand geology, and an overview of the Isotopic Atlas recently produced as part of the Exploring for the Future Program.

The clean energy transition will require a vast increase in metal supply, yet discoveries of new mineral deposits are declining. Recently, several case studies have demonstrated links between electrical conductors imaged using magnetotelluric (MT) data and mineral deposits. Use of MT methods for exploration is therefore growing but the general applicability has not yet been tested. We look at spatial relationships between conductors and three deposit styles and find that volcanic hosted massive sulfide (VHMS) and copper porphyry deposits show weak to moderate correlations with conductors in the upper mantle. In contrast, orogenic gold deposits show strong correlations with mid-crustal conductors. These differences likely reflect differences in the way these deposits form, and suggest a metamorphic-fluid source for orogenic gold is significant. The resistivity signature can be preserved for hundreds of millions of years, and therefore MT can be a powerful tool for mineral exploration.

Compilation of age and endowment data on volcanic-hosted massive sulfide (VHMS), porphyry copper, orthomagmatic nickel, orogenic gold, granite-related rare metal and pegmatite deposits (nearly 1200 deposits from 21 mineral provinces) indicate that metallogenic patterns change over time. For much of Earth’s history, the metallogenesis of convergent margins is marked by a relatively systematic temporal progression of deposits, the convergent margin metallogenic cycle (CMMC): VHMS, calc-alkalic porphyry copper and orthomagmatic nickel → orogenic gold → alkalic porphyry copper, granite-related rare metal and pegmatite. Typically CMMCs last 70-170 Myr, and the progression appears to be related to the convergent margin tectonic cycle (Collins and Richards, 2008). Prior to ~3100 Ma, however, CMMCs are not recognised. Rather, these old mineral provinces are characterised by long metallogenic histories (400-500 Myr) with an irregular distribution of deposits. The Mesoarchean to Mesoproterozoic is characterised mostly by mineral provinces with short (80-150 Myr) metallogenic histories and a single CMMC. Between 1900 Ma and 1800 Ma, however, some mineral provinces (e.g. Trans-Hudson and Sveccofennian) are characterised by multiple CMMCs, with total metallogenic histories that last up to 200 Myr. Paleoproterozoic provinces with multiple CMMCs formed by the consumption of internal seas, whereas mineral provinces on outward-facing convergent margin typically have only one CMMC. After ~800 Ma, convergent margins are mostly long-lived (290-480 Myr) and are characterised by multiple CMMCs with complex metallogenic histories. The changes in the metallogenesis of convergent margins reflect changes in tectonic processes through time. Prior to 3100 Ma, stagnant lid tectonics, which did not involve subduction, resulted in the formation of oceanic plateaus with irregular periods of mineralisation. After the initiation of subduction at ~3100 Ma, the style of metallogenesis changed. The dominance of provinces with a single CMMC from 3100 to 800 Ma suggests that convergent margins were unstable and could be shut down easily. This is consistent with models of shallow-break-off subduction whereby the subducting slab breaks off at shallow levels due to the lower plate strength in the Archean and the early part of the Proterozoic. When the slab breaks off, the subduction system shuts down and produces a single CMMC. Only in cases where factors such as closure of internal seas force continued subduction do multiple CMMCs occur. The change to longer metallogenic histories and multiple CMMCs at ~800 Ma is likely the consequence of the cooling of the mantle, which increases plate strength, allowing subduction of cold slabs deeper into the mantle and more stable convergence: continuous ridge push and the density of oceanic crust causes re-initiated of subduction further outboard rather than complete termination of subduction when the convergent margin is perturbed by the accretion of an exotic block or other tectonic event. Subduction only terminates upon collision of two major crustal blocks. As a consequence, the metallogenic history or geological young convergent margins is long with multiple CMMIs and/or complex temporal interleaving of deposit types.

Hydrogen for energy storage and transport is a key part of the energy transition. Caverns in salt formations can provide high integrity and large-scale storage (>200 GWh). Australia has several basins with thick salt in the subsurface that are prospective for underground hydrogen storage and Geoscience Australia's archive of digital data and physical samples is a crucial resource in assessing these deposits and finding more. New models for the deposition of giant salt deposits, new technologies and the new energy landscape make salt and hydrogen an exciting research frontier.

For the first time in Australia, ground gravity, airborne gravity/gravity gradiometry, and satellite gravity observations have been combined to produce a series of National Gravity Grids covering an area more than twice the size of Australia. This involved the combination of observations made on the land, in the air, and by satellite - more than 1,800 ground gravity surveys, 14 airborne gravity and gravity gradiometry surveys, and satellite gravity observations. Underpinning this accomplishment is the Australian Fundamental Gravity Network - a series of gravity benchmarks that allow the joining of gravity data into a seamless whole. This presentation will discuss both the utility of the network and how it feeds into the production of the grids, plus the process of creating the national scale grids using such varied sources of gravity data.

The presentation will introduce the basic components of the drone/UAV/RPAs, summarise the rules for operating a drone as part of a business or undertaking (including operating under a Remotely Piloted Aircraft Operators Certificate – ReOC) and present some of the science and scientists utilising RPAs for their work at Geoscience Australia and beyond. The talks will include environmental research in Antarctica, landscape analysis after large earthquakes, machine learning to spot dangerous sharks and validating satellite reflectance, all with the assistance of drones.

Australia, like the rest of the world, is forward looking and implementing a range of initiatives to support its transition to a lower carbon future. This presentation will focus on emerging energy resource commodities that have placed Australia on its path to a low carbon economy and how Geoscience Australia’s work program supports the industry’s adaptation to the required change in energy mix. Starting with an overview of Australia’s oil & gas exploration history, the talk will highlight the many significant discoveries, the remaining resource potential and the emergence of new energy resource commodities.

Satellite navigation is an important capability in our modern lives—we use it to find the nearest petrol station, order food at home, and track an arriving package. Accurate satellite-enabled positioning and timing technology is also becoming vital in many industrial sectors of the economy, including transport, agriculture, resources, and utilities. On behalf of the Australian government and in partnership with New Zealand, Geoscience Australia is improving satellite navigation capability for everyone with the Southern Positioning Augmentation Network, or SouthPAN. SouthPAN is a Satellite-Based Augmentation System that will use new spacecraft, ground sensors, and other infrastructure to broadcast corrections that complement existing Global Navigation Satellite Systems—like GPS, for example. SouthPAN services will commence in 2022 and be progressively improved in the coming years, ultimately being used in their most critical application: by aircraft to land at airports.

Characterising earthquake hazard in low seismicity regions is challenging, due to both the inherent lack of data and an incomplete theoretical understanding of the controls on earthquake occurrence away from plate boundaries. In the plate boundary paradigm, elastic rebound theory predicts that cycles of strain accumulation and release will result in regular, or quasiperiodic, recurrence of large earthquakes on individual faults. Analysis of a global compilation of long-term earthquake records shows that this largely holds in plate boundary regions, but begins to break down in intraplate and other low seismicity regions, where more irregular, or aperiodic, earthquake recurrence is observed. In this talk the Otago region of southern New Zealand is used as a case study of a low seismicity region with evidence for aperiodic earthquake recurrence. New paleoearthquake and slip rate data are used to extend the record of faulting back more than 100 ka on two faults, the Hyde and Dunstan faults. These data allow the variability of earthquake rates on these faults to be characterised, with novel Bayesian methods developed to forecast the probability of future earthquakes. Finally, the talk discusses the potential for application of these methods in the Australian context.

Perth Canyon is Australia's second largest submarine canyon, and its elongate and continental shelf-incising morphology contrasts with Australia's more prolific slope-confined canyons. The canyon's sinuous course extends for 120 km from the continental shelf break (~180 m depth, only 50 km offshore from Perth) to its fan at the foot of the continental slope (~4500 m). This seminar will describe the application of a new, internationally-collaborative mapping approach to capture the complexity of the canyon and to link its modern morphology to subsurface data and thereby reconstruct its geological evolution. Infilled incised valleys found in seismic data beneath the canyon headwall suggest that the canyon initially incised in the Late Cretaceous (around 70 million years ago), and subsequent incisions and canyon activity have since declined in scale. Repeat surveys of the canyon headwall following two relatively large earthquakes in 2018 reveal minimal instability of the seafloor and suggest that the canyon is now less active than in it has been in its geological past.