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.
Collaboration between BHP and the EarthByte Group at the University of Sydney Aimed at implementing big and complex spatio -temporal data analysis and modelling to support the needs of BHP in global resource exploration Advance the integration and analysis of physical, chemical and dynamic properties of the Earth. Build on the EarthByte Group’s expertise in constructing a virtual Earth through geological time and to connect BHP’s data to EarthByte’s plate motion models, global data sets and tectonic, geodynamic and surface process modelling tools Four programs, (1) Plate Tectonics and Geodynamics, (2) Paleogeography, (3) Surface Processes and (4) Exploration (with a focus on copper) Integration of geodata through geological time, coupling plate reconstructions with geodynamic models, constructing dynamic paleo-elevation models, designing adaptable landscape evolution models and providing key inputs for spatio -temporal data analysis for global exploration. All programs are interconnected in multiple ways, e.g. copper exploration depends on tectonic and geodynamic models, paleo-elevation and denudation to understand their formation and preservation Phase 2 of the project builds on phase 1, and will extend spatio -temporal data-model connectivity substantially Full plate reconstructions from 1 Ga to present Phase 1 objectives: GPlates training for BHP team – completed (and ongoing) Kinematic testing and improvements of 1 Ga plate motion model – completed Improved useability of model (e.g., turn deformation on/off) Implementation of new Tethyan model – underway Standardisation of Plate IDs and absolute reference frame back to 1 Ga – on track Improvements to flat slab geometries – on track Geodynamic model run – depending on RA onboarding timeframe Integration: Plate models and geodynamic outputs will be used by other STELLAR programs Collaboration with BHP: Key regions already identified (e.g., Urals, Tethys, and east Asia in Phase 1. GoM , Zechstein Basin, and others next year) + some key data already discussed. Personnel: Sabin Zahirovic (Lecturer, ARC DECRA Fellow) Roberta Carluccio (STELLAR Research Associate) Youseph Ibrahim (STELLAR research assistant) Chris Alfonso (STELLAR research assistant) Sydney Informatics Hub support (TBA) Satyam Pratap Singh (STELLAR PhD student joint with Program 2*) * accepted into USyd PhD program but awaiting confirmation of PREA scholarship. Paleogeography Phase 1 objectives: Paleobathymetry grids (and workflows) using our traditional method (incl. oceanic basement depth, sediment thickness, LIPs and their conjugates, passive margins) – 0-250 Ma Enhanced paleobathymetry grids (and workflows) which merges our traditional workflow (but additionally incorporates the reconstruction of major seamount chains) with reconstructed present day bathymetry - 0-250 Ma Broad-based paleo-topography maps (and workflows), which includes paleo-geographies, dynamic topography, tectonic topography for rifts and passive margins and a…
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.
Dr. Ben Mather Computational Geophysicist Sydney Informatics Hub School of Geoscience The University of Sydney Recent Publications B. Mather, L. Moresi, P. Rayner, Adjoint inversion of the thermal structure of Southeastern Australia . Geophys . J. Int. 219, 1648–1659 (2019). B. Mather, R. Delhaye , PyCurious : A Python module for computing the Curie depth from the magnetic anomaly. J. Open Source Softw . 4, 1544 (2019). B. Mather, J. Fullea , Constraining the geotherm beneath the British Isles from Bayesian inversion of Curie depth: integrated modelling of magnetic, geothermal, and seismic data. Solid Earth. 10, 839–850 (2019). B. Mather, T. Farrell, J. Fullea , Probabilistic Surface Heat Flow Estimates Assimilating Paleoclimate History: New Implications for the Thermochemical Structure of Ireland. J. Geophys . Res. Solid Earth. 123, 12 (2018) doi:10.1029/2018JB016555. Background I have a background in geophysics with a focus on Bayesian inversion of thermochemical properties of the lithosphere subject to available data and their uncertainties. Research interests and expertise I am interested in integrating geophysical and geochemical observations with tectonic plate reconstructions to produce data-driven studies of Earth dynamics. Such integration of data with models can unearth vital knowledge on the processes that drive mineralisation . In conjunction, I am working on numerical models of fluid flow in the Sydney Basin to understand groundwater dynamics in response to landscape evolution.
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.