Reconstructing magma pathways to understand how oceanic crust forms
Lead Supervisor: Dr Andy Parsons
Location: University of Plymouth, School of Geography, Earth, and Environmental Sciences
Duration: 8 weeks
Suitable undergraduate degrees: Geology, Geophysics, Earth Sciences
Earth’s network of mid-ocean ridges represents the world’s largest volcanic system, responsible for the creation of oceanic crust, which covers >60% of the Earth’s surface. These mid-ocean ridges form plate boundaries between diverging tectonic plates, which have been fundamental to the transfer of heat, mass, and element cycling between Earth’s mantle, lithosphere, oceans, atmosphere, and biosphere, since the inception of plate tectonics over 2 billion years ago.
Despite their importance to the planetary-scale evolution of our planet, the processes responsible for crust formation at mid-ocean ridges remain poorly constrained due to the difficulties of accessing the seafloor and the rocks beneath it. Subaerial portions of oceanic lithosphere known as ophiolites, which have been emplaced and exposed upon the continents, provide one of the best opportunities to investigate mid-ocean ridge processes. However, deformation associated with the emplacement of the ophiolites can deform their original structure, obscuring their record of crustal formation processes. This problem can be overcome using paleomagnetic analyses to restore the ophiolite to its pre-obduction structure and orientation.
In order to understand how oceanic crust forms, this project will combine paleomagnetic and geochemical analyses to constrain, (1) the pre-obduction structure of the Oman ophiolite; and (2) how magma flowed through the sheeted dyke complexes of the Oman ophiolite, which facilitated magma migration from the melt lens to the seafloor.
Using cutting-edge facilities at the University of Plymouth’s Palaeomagnetism Laboratory, the successful candidate will measure the remanent magnetism of sheet dyke samples from the Oman ophiolite to restore its pre-obduction structure. Once restored, anisotropy of magnetic susceptibility (AMS) analyses of sheeted dyke samples will constrain the directions of magmatic flow with respect to the pre-obduction structure of the Oman ophiolite. Handheld X-ray fluorescence (XRF) analyses will measure the wholerock geochemistry of sheeted dyke samples to constrain the crystal fractionation trends of the magma, which will reveal the evolution of magma chemistry as it migrated away from a melt lens.
After data acquisition, the successful candidate will have the opportunity to process and interpret their data to understand how magma flows through the sheeted complex before erupting onto the seafloor. Training in paleomagnetic analysis will be provided by Dr Parsons and Prof Morris. Training in XRF analysis will be provided by Dr Harris and Ms. Wiggins. Training in data interpretation and general concepts in marine geoscience will provided by all supervisors. Towards the end of the placement, findings of this research and its implications for crust formation processes at mid-ocean ridges will be presented in a short report produced by the successful candidate, with help from supervisors.
The successful candidate will join our vibrant and active research group of students, postdocs, and faculty from the University of Plymouth, University of Cardiff, and University of Montpellier, which meets regularly in-person and online. The results of this project will eventually form parts of a peer-reviewed publication, which the successful candidate will be offered the opportunity to contribute to. For further information, interested students can contact Dr Andy Parsons (email@example.com).