From the mantle to the seafloor: How do oceanic core complexes form at mid-ocean ridges?

Applications are invited for a 3.5 years PhD studentship. The studentship will start on 1 October 2025
oceanic core complexes
Mylonitized gabbro from the Atlantis Massif Oceanic Core Complex, Mid-Atlantic Ridge

Apply 

To apply for the ARIES Doctoral Training Partnership studentship please simply click on the ‘online application’ link below for PhD Geological Sciences : 
Online application
Within the Research section of the application form, in the following fields, please add: 
  • Proposed project title/studentship title: add From the mantle to the seafloor: How do oceanic core complexes form at mid-ocean ridges? 
  • Proposed supervisor: add Dr Andy Parsons 
  • Studentship Code: add ARIES 25-10 Parsons
When the application asks for a research proposal, please just upload a blank document. A research proposal is not needed for this programme as you are applying directly to a studentship project. 

Application guidance 

It is important that you follow the instructions above or your application for this studentship may be missed and therefore will not be considered. 
Before applying, please ensure you have read the Doctoral College’s general information on applying for a postgraduate research degree.  
For more information on the admissions process please contact research.degree.admissions@plymouth.ac.uk. 
Director of Studies:  Dr Andrew Parsons  
2nd Supervisor:  Dr Michelle Harris  
3rd Supervisor: Professor Sandra Piazolo, University of Leeds
4th Supervisor: Dr Jeremy Deans, University of Southern Mississippi
Applications are invited for a 3.5 years PhD studentship. The studentship will start on 1 October 2025 

Project description 

At slow-spreading mid-ocean ridges, fault systems known as Oceanic Core Complexes [1] (OCCs) exhume mantle rocks to the seafloor, creating hydrothermal systems that directly impact ocean chemistry, seafloor mineralization, lithospheric rheology, and microbial ecosystems [1-2]. Despite their importance, the formation of OCCs is a poorly understood process which must be constrained to fully understand the how OCCs and mantle exhumation impact our oceans [1-5]. This project will address this fundamental tectonic and marine geoscience problem with a new understanding of how OCCs form. 
In 2023, International Ocean Discovery Program (IODP) Expedition 399 collected 1.2km of rock core (U1601C) from the Atlantis Massif OCC on the Mid-Atlantic Ridge [1]. This PhD project investigates the deformation processes that control OCC formation through analyses of U1601C, focusing on the roles of ductile deformation and magmatism as drivers of strain localization during OCC formation [3-4].  

Methodology and training

  • Microstructural analyses will constrain deformation process recorded in U1601C using state-of-the-art facilities at the Plymouth Electron Microscopy Centre. 
  • The candidate will be trained in cutting-edge techniques including Electron Backscatter Diffraction, Wavelength Dispersive Spectroscopy, and Element Mapping to constrain deformation kinematics, temperatures, and extent of magmatic deformation [3-4].
  • The candidate will integrate their microscale analyses with borehole geophysics [5] from Site U1601, using industry-standard software to constrain the km-scale structural evolution of Atlantis Massif. 
  • The candidate will test hypotheses and constrain new models for the roles of magmatism and ductile deformation during OCC formation [1, 3-5].  
The PhD candidate will develop expertise in electron microscopy, petrophysics, and deformation processes. They will join a world-leading international network of >25 IODP researchers conducting multi-disciplinary research on Atlantis Massif [1], with opportunities to participate in IODP workshops, training, and applications to sail on future IODP expeditions. They will receive support and training to present their work at international conferences and through peer-reviewed publications. These opportunities will provide a strong foundation of transferable skills and expertise for a career in geoscience research.  

Person specification

We seek enthusiastic candidates with an Earth Sciences related degree and interests including structural/microstructural geology, plate tectonics/marine geoscience and big-picture Earth Science questions. 

Research Culture at Plymouth: 

The candidate will join the vibrant Marine Geoscience research group at SoGEES run by Parsons and Harris. Parsons and Harris have an open-door policy for research students. Supervision is tailored to best fit the candidate, whether that be regular informal updates, or scheduled meetings and reporting. Formal meetings with the full supervisory team will also be scheduled to ensure the candidate develops a collaborative relationship with external supervisors. 
At SoGEES the candidate will be part of a thriving postgraduate community with students from a range of disciplines that form a peer support network. With Parsons and Harris, the candidate’s immediate research group meet regularly to discuss papers and present active research to the wider research community via the Centre for Research in Earth Sciences (CRES) that Harris leads. CRES meets fortnightly to discuss research activities and also informally in social settings. 
Externally, the candidate will interact and build links with the IODP Expedition 399 research team of >25 international scientists, who are actively working and collaborating on cross-disciplinary research on Atlantis Massif. Parsons’ and Harris’ experience with this group and the wider IODP community will enable the candidate to quickly build their own international network of collaborators. 

Supervisory Team: 

Dr Andy Parsons (new investigator) is an expert in plate tectonics, microstructural deformation, and marine geoscience research and teaching, including cutting-edge electron microscopy techniques. His work (24 papers) is recognized by national and international prizes and supported by successful research grants (e.g., NERC; Geol. Soc. London). Parsons has been lead-supervisor of four MGeol projects and three ARIES REP projects, and co-supervised 1 PhD project; four of his students have since enrolled in MSc, ARIES PhD, and postdoc programmes. 
Parsons will be supported by Dr Michelle Harris (Plymouth), a leading expert in marine geoscience and seafloor alteration geochemistry (successfully supervised 3 UoP PhDs in marine geoscience, 1 as DoS). Externally, Prof Sandra Piazolo (Leeds), a world leader in microscale analyses of melt- assisted deformation, and Dr Jeremey Deans (Southern Mississippi), a leading expert in structural geology and petrophysics, will provide additional training and supervision in their areas of expertise, and expand the candidate's network beyond Plymouth. All supervisors have conducted and published past research on the Atlantis Massif OCC. Collectively, this supervisory team has the expertise to supervise and train the candidate in all aspects of the project and provide a supportive environment for them to develop their research identify and network. 

Additional Project Information: 

Mid-ocean ridges have been responsible for the formation of Earth’s oceans and the persistence of plate tectonics for >2 billion years. At slow-spreading mid-ocean ridges, fault systems known as Oceanic Core Complexes (OCCs) create new lithosphere (outermost rocky layer of Earth) by exhuming deep mantle rocks to the seafloor[1]. Reactions between mantle rocks and seawater alter seafloor and ocean chemistry through hydrogen production, carbon sequestration, and metal-sulphide mineralization[2]. Crucially, the full impacts of these processes on global ocean chemistry and plate tectonics cannot be constrained without understanding how OCCs exhume mantle rocks to the seafloor[1-2]. 
In 2023, IODP Expedition 399 (including lead-supervisor Parsons) collected a 1.2km rock core (U1601C) from the Atlantis Massif OCC at the Mid-Atlantic Ridge[1]. The unprecedented completeness of the core presents new opportunities to investigate OCC formation at a greater resolution than ever before[1]. This PhD project capitalizes timely on the new, unique, and immediate research opportunities offered by U1601C.
This project will determine the role of ductile deformation and magmatism during formation of Atlantis Massif, through microscale analysis of U1601C[3-4]. This includes testing the hypothesis that magmatism drives deformation during OCC formation[3-4]. 
The project has two components: 
  1. The candidate will quantify the conditions of deformation in U1601C using analytical facilities (Years 1-2) at the Plymouth Electron Microscopy Centre. This includes training in state-of-the- art electron microscopy techniques from Parsons, Harris, and Piazolo (Plymouth and Leeds) to quantify deformation temperatures and kinematics and role of magmatism during deformation[2- 4]. Initially, the candidate will analyse samples collected by Parsons. They will then visit the Bremen Core Repository to observe the full 1.2 km U1601C core in-persons and select additional targeted samples based on their initial analyses. The candidate will integrate their data with existing thermal models for Atlantis Massif to understand how the recorded deformation and magmatism controlled the formation of the OCC as it cooled.
  2. The candidate will use IODP Exp 399 borehole geophysics datasets to reorientate the core into N-E-S-W coordinates[5] (Year 2) using software and expertise provided by Deans and the European Petrophysics Consortium. This includes visits to Univ. Southern Mississippi and Leicester for training. This will allow the candidate to relate their microscale data to the kilometre- scale 3D structure of Atlantis Massif to determine how observed ductile shear zones and magmatism control OCC formation. Through this micro-to-macro-scale data integration, the candidate will develop the first 3D structural model for Atlantis Massif (Year 3) that explains the roles of shear zones and magmatism during OCC formation. 
The supervisory team will provide quality training and supervision from experts in their fields to support the development of the candidate’s international research identify. At Plymouth, the candidate will be supported further with transferable skills courses to develop their research, communication, technical, and managerial expertise. Science communication will be developed through conference presentations and peer-reviewed publications. These opportunities will give the candidate every prospect of becoming a leading expert in geoscience research, with a diverse set of transferable skills applicable to the research, technology, engineering, and educational sectors.

References 

Lissenberg CJ, Parsons AJ, et al. (2024). A long section of serpentinized depleted mantle peridotite. Science, 385, 623-629. DOI:10.1126/science.adp1058.
Schwarzenbach E, Harris M (2023). Hydrothermal alteration of the oceanic lithosphere. Reference Module in Earth Systems and Environmental Sciences. Elsevier. DOI:10.1016/B978-0-323-99762-1.00016-4 
Casini L, Maino M, Sanfilippo A, Ildefonse B, Dick HJ (2021). High‐Temperature Strain Localization and the Nucleation of Oceanic Core Complexes (16.5° N, Mid‐Atlantic Ridge). Journal of Geophysical Research: Solid Earth, 126(9), p.e2021JB022215. DOI: 10.1029/2021JB022215 
Gardner RL, Piazolo S, Daczko NR, Trimby P. (2020). Microstructures reveal multistage melt present strain localisation in mid-ocean gabbros. Lithos, 366, p.105572. DOI: 10.1016/j.lithos.2020.105572 
Deans JR, Yoshinobu AS (2019). Geographically re-oriented magmatic and metamorphic foliations from ODP Hole 735B Atlantis Bank, Southwest Indian Ridge: Magmatic intrusion and crystal-plastic overprint in the footwall of an oceanic core complex. Journal of Structural Geology, 126, pp.1-10. DOI: 10.1016/j.jsg.2019.05.001 

Eligibility 

Applicants should have a first or upper second class honours degree in an Earth Sciences related discipline.
If your first language is not English, you will need to meet the minimum English requirements for the programme, IELTS Academic score of 6.5 (with no less than 5.5 in each component test area) or equivalent.
ARIES is currently awaiting confirmation of funding under the BBSRC-NERC DLA award scheme, which is expected shortly. Funding for this studentship is subject to this confirmation.  
Successful candidates who meet UKRI’s eligibility criteria will be awarded a fully-funded ARIES studentship of fees, maintenance stipend (£19,237 p.a. for 2024/25) and research costs.
A limited number of ARIES studentships are available to International applicants. Please note however that ARIES funding does not cover additional costs associated with relocation to, and living in, the UK. 
NB: The studentship is supported for 3.5 years of the four-year registration period. The subsequent 6 months of registration is a self-funded ‘writing-up’ period. 
ARIES is committed to equality, diversity, widening participation and inclusion in all areas of its operation. We encourage applications from all sections of the community regardless of gender, ethnicity, disability, age, sexual orientation, and transgender status. Projects have been developed with consideration of a safe, inclusive, and appropriate research and fieldwork environment. Academic qualifications are considered alongside non-academic experience, with equal weighting given to experience and potential. 
For further information, please visit www.aries-dtp.ac.uk.
If you wish to discuss this project further informally, please contact  Dr Andrew Parsons . 
Please see our apply for a postgraduate research programme page for a list of supporting documents to upload with your application. 
For more information on the admissions process generally, please visit our Apply for a postgraduate research programme page or contact the Doctoral College .
The closing date for applications on 8 January 2025. 
Shortlisted candidates will be invited for interview after the deadline. We regret that we may not be able to respond to all applications.  Applicants who have not received a response within six weeks of the closing date should consider their application has been unsuccessful on this occasion.