Alongside our research students, our department generates leading research in Earth and Planetary Sciences. This research occurs through a number of globally recognised research centres and groups, many of which partner with industry and other academic institutions in research collaborations.
Marine Geoscience & Geobiology
Sedimentary Geology and Geochemistry background
The sedimentary record informs us about the dynamics of the coupled Earth system in response to the spectrum of forcings and conditions under which it has operated throughout Earth history. An understanding of these past interactions allows us to draw out the lessons for future climate change that can be learned uniquely from deep-time worlds. Understanding how the complex network of processes and feedbacks that make up the ocean system operate at various time-scales - and over the full range of oceanic variability experienced through Earth’s history - is a high priority for improving projections of future sustainability.
Our geobiology research addresses a similarly important and related question: how do organisms alter and evolve in response to the environment and how do they control geological processes. We seek to understand both fundamental questions such as the environmental triggers for the first complex life on Earth, but also critical questions facing society such as sustainable energy sources, and how geobiological systems can best be managed. Our expertise extends from Precambrian and Phanerozoic environmental change and its influence on animal evolution and radiation, to mechanisms and pathways of biomineralisation, and deciphering the record of past environmental perturbations preserved in the most fine-grained of sediments – shales. We are also actively engaged with alternative energy in the form of the multi-billion dollar energy revolution/environmental crisis associated with shale and coal seam gas, as well as remediation of hydrocarbon and heavy metal pollution.
A particular strength of the group is its interdisciplinary focus, so that research approaches are tailored to best answer a given question and are not constrained by traditional discipline boundaries. Our research utilises modern sediments as well as sedimentary rocks and biominerals as a record of the past, and involves a combination of fieldwork, analytical, experimental and modelling approaches to extract and interpret this information. The group actively participates in the International Ocean Discovery Program (IODP) drilling program. We have access to an excellent range of inorganic, organic geochemical and isotope analysis tools, with a strong focus on high resolution imaging and microanalysis approaches to complement more traditional bulk sample characterisation. This has lead to multiple recent break-through achievements and discoveries, e.g. the terrestrilization of the continents and its role in the rise of oxygen allowing animal evolution, analysis of single oil inclusions by ToF-SIMS, the role of methane clathrate destabilization in the end of the snowball Earth period, detection and characterisation of biomarkers in Archean stromatolites, the influences of carbonate diagenesis on the Precambrian δ13C record as a paleoenvironmental proxy, the first discovery of meiofaunal trace fossils in the sedimentary record, and the key role minerals have in sequestering and preserving organic carbon in the geological record.
Current projects include
- Diagenetic influence on clumped isotope palaeotemperature determinations
- Abrupt changes in the Precambrian global carbon cycle as a potential trigger for the appearance and radiation of animals on Earth.
- Fluid inclusions and molecular fossils (biomarkers) as indicators of evolution in the Precambrian.
- Archaean Stromatolites: signal of the Great Oxidation Event (GOE).
- New in-situ imaging and microanalysis approaches for extracting ultra-high resolution palaeoenvironmental records from sediments and biominerals.
- Impact of early diagenesis on rare earth element cycling and the implications on Neodymium (Nd) isotopes as a tracer of oceanic circulation.
- Depositional environments and palaeoclimate reconstruction in the Miocene.
- Oil spills and bioremediation in cold climates.
- The record and biogeochemical impact of benthic meiofaunal burrowers.
- Biomineralisation: towards a mechanistic understanding of shell formation, and implications for palaeoenvironmental proxies.
- Petroleum geochemistry, including the kinetics of oil and gas generation.
- Quantifying the flux of fugitive greenhouse gasses associated with coal seam gas relative to the natural baseline.
- Re/Os dating of depositional ages and diagenetic events in sediments
- The environmental impact of produced water spills.
- Controls on unconventional shale reservoirs and source rocks.
Geophysics & Geodynamics
This group focuses on understanding the nature and evolution of our planet, as well as other terrestrial planets and moons. We study a wide variety of geophysical and geodynamic processes, ranging from shallow geothermal studies to the deep dynamics of the Earth’s mantle. We are particularly interested in understanding the Earth in a holistic manner, and therefore our research is characterised by a strong multidisciplinary approach. In our studies, we combine concepts/data from a number of disciplines, such as Mineral Physics, Geochemistry, Numerical Modelling, Thermodynamics, Inversion Theory, etc.
- Seismic, gravity, magnetic, GPR and electrical equipment (FEM, TEM, Resistivity).
- Digital data-acquisition system for monitoring geophysical experiments in field and laboratory.
- Physical property laboratory measurement systems (susceptibility, conductivity, seismic velocity, density).
- 9 and 40-kb capability piston-cylinder apparatus.
- A well-equipped computing laboratory with a variety of specialised software and a wide range of software packages are available for data reduction, interpretation, modelling and inversion.
- Geographic Information Systems (GIS) software.
- Field equipment includes electrical resistivity, transient electromagnetic receivers and transmitters, a gravity meter, proton and cesium-vapour magnetometers, dual frequency susceptibility meter, conductivity meter, and palaeomagnetic laboratory, and a multi-channel land refraction or shallow reflection seismograph.
Geochemistry & Petrology
Deep Crust and Lithospheric Mantle group
The Deep Crust and Lithospheric Mantle research group focuses on:
- Nature and structure of the subcontinental lithospheric mantle
- Petrological processes and geochemical evolution in early Earth’s history
- Crustal genesis and mantle evolution
- Mantle plumes and convection within the Earth
- The linkage of the crust and mantle to tackle global scale geodynamic problems
We apply a range of in-situ microanalysis of trace elements and isotopic (eg U-Pb, Nd, Hf, Os-isotopes) measurements to fingerprint geochemical and dynamic evolution of the mantle and deep crust to construct realistic lithospheric structure and evolution models (4-D Lithosphere Mapping), and to understand whole-mantle dynamics through time. We also continue development and application of non-traditional stable isotopes (e.g. Mg, Fe, Cu, Ni, Zn) to a wide range of geological problems in igneous, metamorphic and planetary geology.
The field of our research involves petrology and geochemistry of the deep crust and lithospheric mantle to understand the processes that control the generation and modification of the crust-mantle system over Earth’s ~4.5 billion year history. The crust and the subcontinental lithospheric mantle (SCLM) make up the continental lithosphere, and they are genetically linked. Thus, to understand the evolution of the continental lithosphere through time, we seek information on the history of all levels of the lithosphere — not only for the different layers of the crust, but also for the underlying subcontinental lithospheric mantle. In most cases, our only samples of the deeper levels of the lithosphere are xenoliths carried up by volcanic eruptions (basalts, kimberlites, lamproites).
We integrate geochemical and geophysical data to gain more detailed information on the structure and composition of the continental lithosphere with a particular focus on the nature and role of crust–SCLM interaction through time. The state of the crust–mantle system during the Hadean–Proterozoic period is particular challenging as it preserves a record of phenomena that cannot be easily reconciled with a straightforward plate tectonic paradigm. Another focus of our research is to evaluate the role of crust–mantle interaction in granite genesis, coupled crust–mantle formation and its influence on tectonism, and transport of elements across the crust–mantle boundary.
Finally, we look at the large–scale processes that have created and modified continental crust using stratigraphic, tectonic, and geophysical data to interpret the history and causes of continental assembly and disruption. We seek to understand how these processes may have changed through time and how crustal processes influence the concentration and localisation of economically important elements.
Discoverable Earth and Experimental Petrology group (DEEP MQ)
This laboratory aims to conduct experiments in geoscience, planetary, and materials science over a pressure and temperature range that covers all conditions in the Earth from core to crust, and to pressures that are relevant to other planetary interiors, including the giant gas planets. Research incorporates the study of the solid architecture of planetary interiors (rocks and structures) as well as the fluids and melts that transport materials through the Earth. This research directly complements other major strengths in the department. The great diversity of research interests is indicated by the following list, which is not exhaustive, but indicative of our current and future directions. Many projects will combine these themes:
- Subduction processes: In plate tectonics, most fractionation of elements and isotopes occurs at low temperatures near the Earth’s surface. These materials are returned to the mantle at convergent margins, but their fate during subduction requires high-pressure and temperature experimental investigation of the physical and chemical properties of the rocks, minerals and fluids involved.
- Characterisation of mantle minerals: Macquarie’s strong geophysics group is developing all-encompassing thermodynamically based numerical models of mantle processes, which require experimental determination of the properties of high-pressure phases for many conditions.
- Water in Earth processes: Volcanism and ore deposit formation is controlled principally by the availability of water, which depresses melting temperatures by hundreds of degrees. Quantification of water contents in fluids and melts, minerals in the mantle wedge or in the deeply subducted residues are essential to understanding the budget of water, magmatism and geodynamics. Experiments quantify the transfer of water from subducting slab to mantle wedge, integrating newly developed FTIR, Raman and XANES spectroscopic techniques. This work directly complements work in the High-Temperature geochemistry group’s work in water contents of nominally anhydrous minerals (NAM).
- Early Earth processes: Understanding the origin of Archean granitic rocks and continental crust formation. This relates to understanding when plate tectonics began, and what happened before plate tectonics operated on Earth. This work strongly complements the Geophysics group, which works on the onset of plate tectonics through numerical modelling.
- Enrichment of economically important elements: Melts formed in the mantle represent the first stage of enrichment in economically important metals that lead eventually to the association of ore deposit types such a porphyry Cu and Mo, and gold with convergent margins.
- Planetary science: In the framework of the Macquarie University Planetary Research Centre, experimental facilities are available to investigate the material properties of terrestrial (rock), giant gas and exoplanets, and to guide geophysical models of their behaviour.
- Mechanical properties of minerals and melts: The electrical and mechanical properties, including density and viscosity, of minerals and melts are important to deep Earth, planetary, and cosmochemical applications.
- The deep cycles of the elements of life: Much current attention is given to the deep carbon cycle, whereas the cycling of other important volatile components such as water and nitrogen is neglected. New projects will conduct high-pressure studies of the effect of water and apply the results to geophysical modelling of seismic properties. Nitrogen can be stable as liquid and solid at the mantle conditions, but no experiments have yet been conducted with nitrogen together with Mg, Si and O. We will pioneer this research area.
- Metallic cores and cosmochemistry: The Laser-heated diamond anvil cell (LHDAC) enables direct access to core conditions, whereas multi-anvil apparatus for deformation (D-DIA and MA) experiments allow reproduction of conditions during planetary accretion. Very few labs are capable of experimentation on the core, and deformation studies of the early solar system have been severely neglected up to now. The experimental group have already built a track record in this field.
- Redox processes: Macquarie University geoscientists have internationally recognised expertise in redox effects in earth processes. Redox melting purports that redox changes are just as important as temperature or pressure changes in causing melting, but little experimentation has been done. The association with the Australian Sychrotron (AS) enables previously unattainable XANES analysis of redox states in experimental crystals on a micrometre scale.
Other research groups
The Organic Geochemistry research group works on understanding the early evolution of life, petroleum geochemistry related topics, biogeochemistry of Phanerozoic sequences, and fuel spills and remediation in Antarctica and other places. The organic geochemistry lab is a shared facility at Macquarie University, dedicated to trace hydrocarbon analysis. Collaborators at Macquarie University include the Palaeobiology group in Biological Sciences, the Department of Environment and Geography, and the Department of Chemistry & Biomolecular Sciences. We have many collaborators in other groups in Australia and elsewhere.
This research group focuses on:
- Molecular fossils as indicators of the evolution of life during the Precambrian
- Archaean Stromatolites and signal of the Great Oxidation Event (GOE)
- Petroleum geochemistry
- Oil spills and environmental geonomics
- Recent marine sediments: IODP and marine geoscience
The Uranium-series research group focuses on placing time scale constraints on an array of Earth processes from partial melting, melt ascent, magmatic evolution and degassing of volcanoes to soil production, weathering, sediment transport and landscape evolution. The U-series laboratory (part of the MQGA) is world-class and has the facility to measure U-Th (ICP-MS) Ra (TIMS) and 210Pb (alpha spectrometry) isotopes.
This research group focuses on:
- Processes of partial melting and magma formation
- Uranium mobility in mineralised systems
- Uranium mobility investigated through aquifers (groundwater studies)
- Potential links to climate change
Analytical facilities include a dedicated clean laboratory for radioactive material, access to the Nu Plasma high-resolution multi-collector ICP-MS and the Finnigan Triton TIMS at the Macquarie University GeoAnalytical (MQGA).
- Isotopic characterisation of extraterrestrial materials
- Insights into planetesimal differentiation and core formation
Dating Down Under
Timing of events in the crust and mantle:
- Applications of in-situ U-Pb dating of zircon, rutile, perovskite, (apatite, monazite);
- Hf isotopes in zircon and rutile;
- Os isotopes in mantle sulfides and platinum group minerals
Understanding of micro- and mesoscale processes and their link to macro-scale phenomena
- Microstructural and-chemical analysis
- Experimental deformation and heating of rocks and minerals as well as analogue materials i.e. metals
- Magma genesis at subduction zones
- Volcano geochemistry
- Origin of granitic rocks
- Tonalite-Trondhjemite-Granodiorite Petrogenesis