Dr Michelle Harris, University of Plymouth, School of Geography, Earth and Earth Sciences
Dr Andrew Parsons, University of Plymouth, School of Geography, Earth and Earth Sciences
Prof Chris MacLeod, School of Earth and Environmental Sciences, Cardiff University
Fast-spreading rate ocean ridges are responsible for forming 50% of the world’s oceans, yet the magmatic processes involved in building the crust remain poorly understood. Transportation of melt at these ridges is typically considered as a 2D process, yet lateral variations in seafloor morphology and erupted lava compositions along ridge axes show that there must also be significant along-axis (3D) transport and evolution of melt during formation of the crust. This project aims to discover how this 3D magma transport system operates in upper crustal sheeted dyke complexes along fast-spreading ridges, using field and laboratory analyses of rocks exposed in the Oman ophiolite, a major slice of oceanic crust and mantle exposed on land, representing the only place in the world where this problem may be addressed.
The student will collect samples from sheeted dykes exposed along a >100 km fossil spreading ridge segment in Oman. In Plymouth, they will perform magnetic fabric analyses on these samples to detect imbrication of crystals along dyke margins, use these microfabrics to determine the 3D orientation of magma flow during dyke intrusion, and map out domains of different dyke emplacement directions along the ridge. They will also determine dyke geochemical compositions and relate these to flow regimes. Paleomagnetic analyses will allow the student to correct dyke orientations and flow directions for the effects of later tectonic rotations, thereby reconstructing the Oman spreading ridge system.
The student will be trained in: (i) advanced geological fieldwork techniques (including field description and structural analysis of mafic rocks) during two field seasons in Oman; and (ii) a range of magnetic and geochemical techniques that also have wide applications outside of the specific topic of this project. The project links to a wider NERC-funded investigation of the 3D anatomy of magma transport along fast-spreading ridges, allowing the student to become skilled in collaborative research practices via membership of an interdisciplinary research team addressing a major topic in marine geoscience.
We seek an enthusiastic individual with an Earth Science-related degree, and a passion for fieldwork, geophysics, igneous petrology and structural geology.