Australian Laureate Project “Deep Earth Cycles of Carbon, Water, and Nitrogen”
The separation of the Earth into layers of crust, mantle and core, as well as later redistribution of chemical elements around different parts of the mantle and crust, is governed by melting of rocks.
Melting depends largely on the effects of a few light elements, C, H, O, N, which form the volatile components H2O, CO2, CH4, N2, H2 and NH3. Small amounts of these components cause the melting point of rocks to differ by up to 300˚C and are main drivers of plate tectonics. They determine that only small amounts of alkaline silicate and/or carbonate melts exist in many areas before major melting occurs. These incipient melts are the main cause of the compositional evolution of the Earth’s mantle.
The Earth Evolution group is investigating the effects of volatile components on melting in the mantle, and aspects of the cycling of these elements deep in the Earth. This entails high-pressure experiments, petrology and geochemistry on mantle rocks, their partial melts, and reactions between subducted crustal materials and the mantle.
For information on PhD and Masters degree opportunities, click on the “Projects” box below.
Applications for PhD and MRES scholarships are now open: application deadline is July 31st.
International and domestic PhD scholarships are available that include living stipend and fees for 3 years. Direct entry into the PhD programme at Macquarie requires completion of a two-year Masters degree with a major research component at Distinction level (75%). For applicants with an Honours or shorter Masters degree, there are also MRES/PhD package scholarships which enable completion of MRES as a training pathway to a Doctoral degree.
There is also an option for co-tutelle projects with partner universities.
Please visit the how-to-apply website page for more information.
Note that applications require you to include a research proposal. You are encouraged to discuss this before completing your on-line application. Informal enquiries should be addressed to Prof. Stephen Foley (Stephen.firstname.lastname@example.org).
Enquiries about openings further into the future are also welcome.
Macquarie University runs a Masters of Research (MRES) degree, which is a two-year degree with the entire second year spent on a research project leading to a thesis. More information is available here.
Potential PhD or MRES projects:
Specific project themes include those listed below, but students are also encouraged to suggest their own research themes.
- Partial melting of hydrous pyroxenite in the arc mantle wedge: consists of high-pressure experiments on the role of hydrous pyroxenite in producing primary and intermediate arc magmas and volcanic rock
- Melting in reducing conditions (joint project with Australian National University): an experimental project investigating the melting conditions and melt compositions with carbon but no carbonate (C, H2O and CH4).
- The behaviour of nitrogen in the early stages of subduction: an analytical and experimental project on the minerals and reactions involved in the transport of nitrogen during subduction.
- Reaction between crust and mantle in subduction zones: an experimental investigation of reaction zones and melts produced by reaction of subducted crust in the mantle.
- Stability and chemistry of spinel in mafic volcanic rocks: an experimental and analytical investigation of spinels for the information they contain about magma source regions.
- Sources of eastern Australian Mesozoic/Tertiary volcanism: volcanic rocks and their olivine phenocrysts will be used to decipher the mineralogy and history of their mantle sources.
- Transport of elements in the deep crust: an analytical and experimental investigation of trace element distribution between minerals, fluids and melts.
Fieldwork in Australia
Why Study in Australia?
Stephen is Professor in the Department of Earth and Planetary Sciences, specialising in petrology and geochemistry of the igneous rocks and upper mantle rocks. Many alkaline igneous rocks have their origin as partial melts of the Earth’s mantle: investigation of both potential mantle source rocks and the igneous products helps to understand the conditions of melting and compositions of melts. The volatile components C, H, O and N greatly affect the melting process, which is simulated in high-pressure experiments. He also has research interests in geological processes in early Earth history.
Michael finished his PhD at Macquarie early in 2019. He investigates the geochemical behaviour of nitrogen and potassium in magma and mantle rocks. Atmospheric nitrogen is continuously fixed and deposited in marine sediments and recycled to the mantle at subduction zones. The quantification of nitrogen in melting and crystallization processes is the first step in calculating Earth’s nitrogen budgets and tracking the evolution of the atmosphere. Other research interests include the relation of ultrapotassic magmas to the recycling of sediments, mantle metasomatism and multi-stage element fractionation processes.
Chunfei completed his PhD at China University of Geosciences, Wuhan in December 2018. He is engaged in the study of the physical and chemical behaviour of carbon in subduction zones and its role in driving mantle evolution. He is also active in high temperature Ca isotope geochemistry, especially for its application to decoding the origin of alkaline rocks and tracing recycled carbon in the mantle.
Zairong comes from China and is doing a PhD as a cotutelle student between Macquarie University and Muenster University in Germany. She has two main areas of interest: partial melting of peridotite in the presence of reducing fluids (H2O+CH4) in high-pressure experiments; and investigations of trace elements in olivine to identify the source assemblages of basalts in eastern Australia. Besides this, she likes travelling, workout, modern dance and orientational dance.
Mingdi's research interests focus mainly on crust-mantle interaction processes and related magmatism in continental subduction zones. He is using high-pressure, high-temperature experimental methods to investigate reaction mechanisms and products in experiments incorporating different continental materials and peridotite at high- to ultra-high pressure conditions.
Chengyuan has broad interests in geological processes of the solid Earth, including thinning and accretion of the lithospheric mantle, formation and evolution of Archean cratons, deep carbon cycling, thermal evolution of orogenic belts, and arc magmatism. Current projects are on melt/fluid-rock interaction in the lithospheric mantle using peridotite and pyroxenite xenoliths from Cenozoic basalts from north China; melting of carbonate sediments recycled into the deep Earth in the Central Orogenic Belt in north China; and in-situ Rb-Sr dating of K-rich minerals like micas and K-feldspar by QQQ LA-ICP-MS/MS.
Anthony is a Macquarie University-trained geologist and geophysicist, Sydney native and coffee addict. Prior to starting his PhD he served as a tutor, research assistant and casual SEM operator, as well as interim experimental lab manager for nearly 2 years. Following a Masters (MQ) on the electrical conductivity of olivine, Anthony’s Phd topic is the origin and geochemistry of shoshonites, a topic he chose to improve his geochemical skills fed by a deeply held and irrational notion that one should be versed in all fields of geoscience. Through combining geology, geochemistry and experimental petrology, he fully anticipates understanding what makes the shoshonites a great source of mineralisation.
Marina's interests lie in petrology and geochemistry of mantle peridotites as well as the development of improved analytical measurement protocols with LA-ICP-MS. The aim of her PhD project is to acquire low concentration trace elements in silicate phases in a variety of mantle xenoliths, with a special focus on olivine and opx. Marina also hopes to gain new insights into mantle geochemistry by extending the trace element palette to volatile siderophile and chalcophile elements in silicate phases.
Zsanett’s PhD research project focuses on the compositions of melts in the low degree (incipient) melt regime of the upper mantle (~2 to ~7 GPa) using experiments in piston cylinder and multi anvil apparatuses. Melting of four peridotitic rocks, from enriched lherzolites to depleted harzburgites with CO2 and H2O are used to track the oxidized solidus.
Her research interest also focuses on how these incipient melts influence and overprint the surrounding cratonic lithospheric rocks through melt-rock interactions, and their contributions to redox freezing, diamond formation and MARID-like hybrid rock formations.
Josh is interested in identifying and understanding the mineral assemblages in the mantle source of primitive intraplate basaltic provinces in eastern Australia. He is also interested in metasomatic processes which may have affected their source region. These tie into understanding the movement of melts that redistribute volatile components throughout the sub-lithospheric mantle, but cannot be directly observed on Earth’s surface.
News and Events
Earth recycles ocean floor into diamonds
The diamond on your finger is most likely made of recycled seabed cooked deep in the Earth. Traces of salt trapped in many diamonds show the stones are formed from ancient seabeds that became buried deep beneath the Earth’s crust, according to new research by Dr Michael Förster, Prof Stephen Foley and Dr Olivier Alard from the Department of Earth and Planetary Sciences. In experiments recreating the extreme pressures and temperatures found 200 km underground, the team demonstrated that seawater in sediment from the bottom of the ocean reacts in the right way to produce the balance of salts found in diamond. The study, published in Science Advances, settles a long-standing question about the formation of diamonds, showing the salts trapped inside diamonds came from marine sediment. Read more
Research Facilities and Infrastructure
Our new, expanded experimental laboratory opened in April 2019. It contains three multi-anvil presses: a 1000-ton Walker-style (right – the upper photo shows it being lowered into position) and a 2000-ton cubic anvil press (left). Two new automated piston-cylinder apparatuses will be delivered mid-2019 to join two 50-year old manual ones that remain in operation.
The geochemical laboratories of Macquarie Geoanalytical contain all necessary instrumentation for the study of natural rocks and for the analysis of experimental charges: electron microprobes, scanning electron microscope, several Laser-ablation ICP-MS instruments, Raman spectroscopy, XRF and XRF imaging, and TIMS.