A seismic study of the continent-ocean transition southwest of the UK

PLEASE NOTE:  Application deadline date 08 Jan 2024.  Applications are no longer being accepted for this project

 

Project Overview 

At some rifted margins, mantle rocks are exhumed both from beneath the continent and through tectonic extension at the mid-ocean ridge, then hydrated and intruded by melt. This project aims to quantify the evolution of mantle hydration and melting during breakup at such margins, using a new seismic dataset.

Project Description 

The breakup of continents is fundamental to the creation of the Earth’s surface and its oceans but many aspects remain poorly understood. Breakup involves a complex interplay of extensional tectonics and magmatism, resulting in a range of rifted margin types, including a “magma-poor” end-member involving broad regions of exhumed and serpentinised (hydrated) mantle. Breakup at such margins is commonly followed by slow to ultra-slow seafloor spreading, which can also result in mantle exhumation and thus ambiguity about where seafloor spreading starts. Normal faulting plays a key role in supplying fluids driving serpentinisation beneath hyper-extended continental crust but its role in regions of exhumed mantle is less clear. To address these issues, we will image lateral variations in serpentinisation and magmatism at the Goban Spur margin, southwest of the UK using a new dataset of densely-sampled ocean bottom seismic (OBS) data across this margin acquired in September 2023. The student will integrate this dataset with pre-existing wide-angle seismic data and extensive multichannel reflection data along the same profiles and nearby, some of which were newly acquired in 2021. Interpretation will be guided also by results from an electromagnetic survey carried out as part of the same project.

Location: 
University of Southampton/National Oceanography Centre
Training: 

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 at National Oceanography Centre Southampton within the vibrant Ocean BioGeosciences group. The student will also be a member of the University’s Geology and Geophysics research group. Specific training relevant to a future academic career as well across a range of industries (e.g. geohazard assessment, offshore survey and engineering and reinsurance) includes:

Processing of wide-angle seismic data, including quality control of the ocean bottom seismometer (OBS) data and determination of precise seafloor locations of instruments.

Determination of seismic velocities via seismic travel-time tomography and full waveform inversion, including aspects of super-computing.

Subsurface reflection imaging using mirror imaging of OBS data

Downward continuation of available long-streamer multichannel seismic data

Seismic interpretation and evaluation of rifted margin processes, specifically focused on the interaction of magmatism and serpentinisation during the onset of seafloor spreading.

Integration of seismic results with electromagnetic results.   

 

Eligibility & Funding Details: 
Background Reading: 

Bayrakci, G., Minshull, T. A., Sawyer, D. S., Reston, T. J., Klaeschen, D., Papenberg, C., ... & Morgan, J. K. (2016). Fault-controlled hydration of the upper mantle during continental rifting. Nature Geoscience, 9(5), 384-388.

 

Bullock, A. D., & Minshull, T. A. (2005). From continental extension to seafloor spreading: crustal structure of the Goban Spur rifted margin, southwest of the UK. Geophysical Journal International, 163(2), 527-546.

 

Davy, R. G., Morgan, J. V., Minshull, T. A., Bayrakci, G., Bull, J. M., Klaeschen, D., ... & Cresswell, D. (2018). Resolving the fine-scale velocity structure of continental hyperextension at the Deep Galicia Margin using full-waveform inversion. Geophysical Journal International, 212(1), 244-263.