Project EARTH-17-RK3: Magma genesis and transport in subduction zones – theory and computational models.

Supervisor: Prof. Richard Katz

Subduction zones host most of the subaerial volcanism on Earth, representing both a source of hazards and natural resources.  More importantly, subduction-zone magmatism creates the continental crust over geological time.  Despite its importance there are many aspects of subduction-zone magmatism that are poorly understood.  For example,

  • What controls the position of the volcanic front above the subducting slab?
  • Why are metamorphic estimates of equilibrium temperatures beneath arcs so much hotter than typical models predict?
  • What is the role of decompression melting versus hydrous flux melting?
  • What fraction of subducted volatiles (carbon, water) are transported into the deep mantle versus recycled to the surface or stored in the crust?

And many more open questions about the geochemical and geophysical observations of subduction. The complexity of the subduction system makes these questions challenging to answer.

This project will overcome those challenges using new computational tools for simulating coupled mantle convection, petrogenesis and magma transport.  The successful applicant will join a research team that is actively developing the project code.  S/he will contribute to the development of one or more code modules according to interest and background.  S/he will also employ the code to investigate the global systematics of arc volcanism, as a means to understand the processes at depth the control the surface expression.  This may include geochemical signals associated with trace elements, thermal evolution of the lithosphere, or the relationship between devolatilisation of the subducting slab and melting in the wedge.

The student should be prepared to work extensively with scientific software both as a programmer and as a user.  S/he should be enthusiastic about mathematical modelling of physical phenomena and eager to learn both about the dynamics as well as the mathematics.  Code will be deployed on machines from laptops and desktops to the UK’s largest supercomputer, so the student should be willing to struggle with the logistics of software and operating systems. Finally, the student should be motivated to gain a physical understanding of the Earth.  Candidates with first degrees in physics and applied mathematics are strongly encouraged to apply.

Further Reading:

Keller T., R.F. Katz and M.M. Hirschmann, The fate of volatiles in mid-ocean ridge magmatism. Submitted. http://arxiv.org/abs/1608.03841

England, P.C. and R.F. Katz, (2010) Dry melting and thermal advection in the mantle wedge control the location of volcanic arcs. Nature, http://dx.doi.org/10.1038/nature09417