PLEASE NOTE: Application deadline date 08 Jan 2024. Applications are no longer being accepted for this project
Project Overview
The properties of upper oceanic crust are controlled by exchanges of heat and chemicals between the ocean and the Earth’s interior. This project will study their temporal variation in a corridor in the eastern Pacific with unprecedented detail to understand the entire life cycle of an oceanic plate.
Project Description
Oceanic lithosphere makes up 70% of the Earth’s surface, forming at mid-ocean ridges, evolving through physical and chemical exchanges with the ocean, and eventually being recycled back into the Earth’s interior at subduction zones. A key process within this cycle is hydrothermal circulation: seawater penetrates into the crust and upper mantle, reacts with the minerals in the rocks, and exits with an altered chemical composition, often depositing new minerals as it does so. It is difficult to constrain the age range over which this hydrothermal circulation occurs, however much of the interaction happens in the upper part of the crust (“seismic layer 2”) and changes properties that we can measure remotely using acoustic waves.
In this project you will study the evolution of the upper oceanic crust through its entire life cycle in the eastern Pacific – from the East Pacific Rise where it forms to the subduction zone at the Middle Americas Trench, including continuous transects of several hundred km. You will work with several multichannel seismic reflection datasets where the streamer recorded sound waves that have interacted strongly with seismic layer 2 enabling us to constrain sound speed and density. You will use downward continuation to simulate an experiment carried out on the seabed, and then use a combination of the traveltimes of seismic energy and their waveforms to investigate how the properties of layer 2 vary with age. Ultimately you will interpret the results in terms of fluid fluxes and their variation across the plate.
The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted in the School of Ocean and Earth Science at the National Oceanography Centre Southampton. Specific training will include:
Marine geophysical data acquisition through participation in an appropriate research cruise.
Processing of marine seismic reflection data
Analysis of marine seismic reflection data, including aspects of high-performance computing
The background will leave the student well-equipped for a future career in research, in consultancy, or more broadly in marine geophysical surveying.
Ingo Grevemeyer, Cesar R. Ranero, Monika Ivandic; Structure of oceanic crust and serpentinization at subduction trenches (2018). Geosphere, 14: 395–418. https://doi.org/10.1130/GES01537.1
Marjanović, M., Barreyre, T., Fontaine, F. J., & Escartín, J. (2019). Investigating fine-scale permeability structure and its control on hydrothermal activity along a fast-spreading ridge (the East Pacific Rise, 9°43′–53′N) using seismic velocity, poroelastic response, and numerical modeling. Geophysical Research Letters, 46, 11799–11810. https://doi.org/10.1029/2019GL084040
Michelle Harris, Rosalind M. Coggon, Martin Wood, Christopher E. Smith-Duque, Timothy J. Henstock, Damon A.H. Teagle, Hydrothermal cooling of the ocean crust: Insights from ODP Hole 1256D (2017). Earth and Planetary Science Letters, 462, 110-121, https://doi.org/10.1016/j.epsl.2017.01.010.
