We propose that slab-induced plume branching can explain the formation of parallel hotspot chains observed in the oceanic and continental record. Using plate tectonic reconstructions and geodynamic modelling, we demonstrate how subducting slabs deflect and split mantle plumes in the transition zone, generating multiple branches that produce parallel volcanic tracks at the surface.
Numerical models of groundwater flow play a critical role for water management scenarios under climate extremes. Large-scale models play a key role in determining long range flow pathways from continental interiors to the oceans, yet struggle to simulate the local flow patterns offered by small-scale models. We have developed a highly scalable numerical framework to model continental groundwater flow which capture the intricate flow pathways between deep aquifers and the near-surface. The coupled thermal-hydraulic basin structure is inferred from hydraulic head measurements, recharge estimates from geochemical proxies, and borehole temperature data using a Bayesian framework. We use it to model the deep groundwater flow beneath the Sydney-Gunnedah-Bowen Basin, part of Australia’s largest aquifer system. Coastal aquifers have flow rates of up to 0.3 m/day, and a corresponding groundwater residence time of just 2,000 years. In contrast, our model predicts slow flow rates of 0.005 m/day for inland aquifers, resulting in a groundwater residence time of ∼ 400,000 years. Perturbing the model to account for a drop in borehole water levels since 2000, we find that lengthened inland flow pathways depart significantly from pre-2000 streamlines as groundwater is drawn further from recharge zones in a drying climate. Our results illustrate that progressively increasing water extraction from inland aquifers may permanently alter long-range flow pathways. Our open-source modelling approach can be extended to any basin and may help inform policies on the sustainable management of groundwater.
The STELLAR project is a collaboration between BHP and the EarthByte Group at the University of Sydney, aimed at implementing spatio-temporal data analysis and modelling to support global resource exploration. The project integrates plate tectonic reconstructions with geodynamic models across four programs—plate tectonics, paleogeography, surface processes, and copper exploration—to advance understanding of how geological processes control the formation and preservation of mineral deposits.
Long-lived, widespread intraplate volcanism without age progression is one of the most controversial features of plate tectonics. The eastern margin of Australia and Zealandia has experienced extensive mafic volcanism over the last 100 million years. A plume origin has been proposed for three distinct chains of volcanoes, however, the majority of eruptions exhibit no clear age progression. Previously proposed edge-driven convection, asthenospheric shear, and lithospheric detachment fail to explain the non age-progressive eruptions across the ~5000 km wide intraplate volcanic province from Eastern Australia to Zealandia. We model the subducted slab volume over 100 million years and find that slab flux drives volcanic eruption frequency, indicating stimulation of an enriched mantle transition zone reservoir. Volcanic isotope geochemistry allows us to distinguish a HIMU reservoir (>1 Ga old) in the slab-poor south, from a northern EM1/EM2 reservoir, reflecting a more recent voluminous influx of oceanic lithosphere into the mantle transition zone. We provide a unified theory linking plate boundary and slab volume reconstructions to upper mantle reservoirs and intraplate volcano geochemistry.
In the driest inhabited continent on Earth, aquifers of the Sydney-Gunnedah-Bowen Basin are essential for Australian agriculture production, yet they experience progressively declining water level trends. In addition, groundwater discharge from the basin into the coastal ocean, a process now widely recognised as being important for providing significant inputs of nutrients and solutes to the oceans, has never been modelled. We have constructed a 3D Bayesian numerical groundwater flow model spanning the entire width and depth of this continent-scale basin. Our model assimilates groundwater recharge rates from water chloride concentrations, and borehole temperature measurements to constrain hydrothermal flow within the basin. We show that inland aquifers exhibit slow flow rates of 0.5 cm/day, resulting in a groundwater residence time of approximately 383 thousand years. In contrast, coastal aquifers have flow rates of approximately 30 cm/day, and a groundwater residence time of just 182 years. Our open-source modelling approach can be extended to any basin and help inform policies on the sustainable management of groundwater. In the future, our approach will enable time-dependent modelling of groundwater flow in response to uplift, erosion and climate change.
Investigating the link between changes in subducting slab flux and the triggering of intraplate volcanism, with a focus on the volcanic record of eastern Australia.
This talk presents an overview of research integrating geophysical and geochemical observations with tectonic plate reconstructions to produce data-driven studies of Earth dynamics. Topics include Bayesian inversion of the thermal structure of the lithosphere, probabilistic heat flow estimation, and numerical modelling of groundwater flow in the Sydney Basin.
Intraplate volcanism triggered by subducted volatiles during bursts in slab flux
Intraplate volcanism triggered by the release of subducted volatiles during bursts in slab flux
Partial melting of ancient subducted slabs provide a framework through which to explain non-age progressive volcanism in a region of anomalous mantle composition.