Caribbean Subduction: Seismic Imaging Melt and Volatiles in the Lesser Antilles

Dense oceanic tectonic plates sink beneath buoyant continental plates at subduction zones. The ocean plate adds volatiles like water to the mantle, lowering the melting temperature, and enabling melting and eventually volcanoes at Earth’s surface. Subduction zones are an important part of plate tectonics, in particular regarding the input of volatiles like water to the system. The pathways of volatiles and melting in subduction zones are relatively unknown, and yet fundamental to our understanding of the forces that drive melting and dictate the location of volcanoes. This study will image water and melt in the Antilles Subduction Zone using data from a new 30 instrument seismic deployment on the ocean floor and also stations located on Caribbean Islands. This is the first time Atlantic Plate subduction has been imaged at this scale and resolution. It represents an exciting opportunity to investigate an ocean plate formed at slow spreading, the role of fracture zones in the downgoing plate on water storage and transport, and a large, systematic variation in ocean plate sedimentation within one system.

Seismic methods such as joint surface wave and receiver function imaging and/or joint surface wave and body wave imaging will be developed. The project also has the possibility of developing joint interpretation and/or inversion with magnetotelluric data. These images will provide powerful constraints since shear velocity is strongly affected by volatile content and the ratio of shear velocity to compressional velocity is strongly affected by melt. The joint inversions will represent the culmination of the project and will be fully integrated with geochemistry and geodynamic modelling. The goal will be a systematic global evaluation of volatiles and melting in subduction systems.

All doctoral candidates will enroll in the Graduate School of NOCS (GSNOCS), where they will receive specialist training in oral and written presentation skills, have the opportunity to participate in teaching activities, and have access to a full range of research and generic training opportunities. GSNOCS attracts students from all over the world and from all science and engineering backgrounds. There are currently around 200 full- and part-time PhD students enrolled (~60% UK and 40% EU & overseas).

The student will gain experience with cutting edge ocean bottom seismic equipment. The student will develop skills and learn techniques from passive source seismology as a member of one of the largest and most active geophysics groups in the UK. The student will learn to cull, process, and invert seismic data using dense seismic arrays. The student will have excellent computational facilities and be trained in programming skills for Seiscomp3, FORTRAN, Matlab, SAC, and the UNIX operating system. The student integrate the seismic results with petrologic and active seismic experiments currently being done in the region by collaborators at Univ. of Liverpool, GFZ-Potsdam, Univ. Bristol, University of Durham and Imperial College London to collaborate with colleagues. A wide range of opportunities to develop the range of generic skills essential for successful completion of the PhD and their future career are available through the Graduate School NOCS. The project will also involve field opportunities on land and at sea. This training will prepare the student for a career path in academia and industry.