A PhD position in Geodynamics is open at the School of Earth, Atmospheric and Life Sciences (SEALS) of the University of Wollongong (UOW) and Institut de Physique du Globe de Paris (IPGP), France. The successful candidate will join a research team investigating the links between mantle dynamics, the magnetic field and the evolution of complex life.
The aim of this PhD research is to investigate the effects of mantle convection on the magnetic field as the inner core grew, and possible links with the evolution of complex life.
The objectives of this PhD research are
- to quantify the relationship between sinking of oceanic lithosphere and the evolution of the core-mantle boundary heat flow,
- to quantify the relationships between core-mantle boundary heat flux and the reversal rate of Earth’s magnetic field, and
- to develop core simulations consistent with the predicted evolution of the mantle for direct comparison with paleomagnetic observations.
The successful candidate will work with Associate Professor Nicolas Flament (UOW) and Dr Maylis Landeau (IPGP).
Earth’s outer core consists of liquid iron and nickel, and convection of this low viscosity material with a time scale of the order of 100 years (Glatzmaier and Roberts, 1996) generates Earth’s magnetic field (Elsasser, 1939). It is well established from magnetostratigraphy that the polarity of Earth’s magnetic field reverses episodically. Successive reversals bound periods called ‘chrons’, which last less than half a million years on average (Glatzmaier et al., 1999). However, some ‘superchrons’ may last up to 40 Myr (Cox, 1969), suggesting that the heat distribution in the deep mantle could affect the frequency of reversals of the magnetic field (Glatzmaier et al., 1999).
It is generally agreed that low equatorial core-mantle heat flow promotes geodynamo stability and therefore low reversal frequencies (Biggin et al., 2012; Glatzmaier et al., 1999; Olson et al., 2010). State-of-the-art reconstructions of past mantle flow developed at UOW, which are consistent with Earth’s volcanic history (Flament et al., 2022; Müller et al., 2022), put us in an ideal position to apply this concept to deep geological times.
The PhD student will track sinking oceanic lithosphere to ensure that Dynamic Earth Models with secular core cooling produce slab sinking rates that are consistent with independent constraints for the last 250 Myr (Butterworth et al., 2014; Van Der Meer et al., 2010), and to verify the proposed link between subduction flux and geomagnetic reversal rate (Hounslow et al., 2018). The PhD student will analyse the evolution of the amplitude of total, equatorial and polar core-mantle boundary heat flow for the period 580-480 Ma, when the reversal rate of the geodynamo was about three times larger than at any other times during the Phanerozoic Eon (Biggin et al., 2012; Meert et al., 2016). We will work with an Honours Student to analyse the core-mantle boundary heat flow predicted by Dynamic Earth Models for Ediacaran times at finer temporal resolution.
A second and more provocative explanation to account for the high reversal rate of the geodynamo during Ediacaran-Cambrian times is that the inner core nucleated during this time. This scenario is consistent with measurements that suggest that the intensity of the magnetic field was weakest at ~565 Ma (Bono et al., 2019; Thallner et al., 2021). The PhD student will work with Dr Maylis Landeau (Institut de Physique du Globe de Paris, IPGP, France), an expert in core dynamics, to investigate the effects of mantle convection on the magnetic field as the inner core grew.
Together, we will implement a core cooling model including a rapid increase in the vigour of core convection when the inner core started growing around 600 Ma (Davies et al., 2022; Landeau et al., 2017). We will use this core evolution model to drive geodynamo simulations with evolving inner-core radius and an imposed history of heterogeneous core-mantle boundary heat flow predicted by Dynamic Earth Models that are consistent with Earth’s volcanic history (Flament et al., 2022; Müller et al., 2022). These geodynamo simulations will predict reversal rates that will be compared to paleomagnetic observations, and a magnetic field strength that will have implications for surface UV radiations.
Faculty: Faculty of Science, Medicine and Health
Study area: Physics
Student type: Domestic students, International students
Student status: Current student in first year of study, Future Students
Scholarship amount
Successful candidates will receive a tax-free stipend of $35,522 p.a. for the duration of the award. Research support for the successful candidate includes computer equipment, travel to conferences, and travel to visit research collaborators.
The most outstanding applicant will receive the Dr Tony Jordan OAM Award, which provides the recipient with an additional stipend.
Duration
3.5 years full-time study
Application process
Please send expressions of interest to Associate Professor Nicolas Flament (nicolas_flament@uow.edu.au) and Dr Maylis Landeau (landeau@ipgp.fr) with the subject line ‘Expression of interest – PhD in Geodynamics’ and including the following documents (in pdf format):
- A cover letter including statement of research experience and interests (maximum two pages)
- A CV, including contact information for at least two references
- Copies of your academic transcripts
Eligibility requirements
The successful candidate will have excellent marks in their undergraduate degree and must have completed a research thesis (e.g. Honours, Masters, MSci) of similarly high quality. Candidates should demonstrate knowledge of solid Earth processes, fluid dynamics, quantitative skills, and programming skills (for example, python).
Application closing date
1 March 2025
Contact information
Nicolas Flament