Tracking magma migration during oceanic crust formation

Lead supervisors: Dr Andy Parsons

Location: School of Geography, Earth, and Environmental Sciences, University of Plymouth

Duration: 8 weeks

Suitable undergraduate degrees: Geology, Geophysics, Earth Sciences

Project background

Oceanic crust, which covers >60% of the Earth’s surface, is created at mid-ocean ridges that collectively represent the world’s largest volcanic system. These ridges are an important type of tectonic plate boundary that forms between diverging tectonic plates. As tectonic plates move away from each other, new oceanic crust is formed along the mid-ocean ridge plate boundary. That oceanic crust then migrates with the tectonic plates towards subduction zone plate boundaries, where it is eventually recycled back into the Earth’s mantle. Mid-ocean ridges and the processes that occur along them, are therefore fundamental to the transfer of heat and mass, and element cycling between Earth’s mantle, lithosphere, oceans, atmosphere, and biosphere, and have been so since the inception of plate tectonics over 2 billion years ago.

Despite their fundamental 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, therefore provide one of the best opportunities to investigate mid-ocean ridge processes. This project will address the problem of oceanic crust formation at a mid-ocean ridge setting by investigating how magma migrated from lower to upper crustal depths during formation of the Oman ophiolite.

In order to track the migration of magma through the Oman ophiolite, the successful candidate will use rock magnetic analyses to identify and measure magmatic foliations and lineations in upper and lower crustal samples from the Oman ophiolite. Analysis of the anisotropy of magnetic susceptibility (AMS) in igneous rocks provides a 3D measurement of crystal orientations, which align in the direction of magmatic flow during crust formation. Using cutting-edge facilities at the University of Plymouth’s Palaeomagnetism Laboratory, the successful candidate will analyse the AMS of lower crustal gabbros and upper crustal dykes. After data acquisition is complete the successful candidate will process and interpret their data to understand how magma flows from the lower to upper crust, before erupting onto the seafloor. Sample sets collected along the spreading-axis of the ophiolite will provide an additional constraint on the how magma migration may vary laterally. Training in paleomagnetic analysis, data interpretation, and general concepts in marine geoscience will be provided by Dr Parsons and Prof Antony Morris. Towards the end of the placement, the findings of this research and its implications for our understanding of crust formation 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 (andy.parsons@plymouth.ac.uk).