UCL Earth Sciences


Nicholas Backhouse

“Developing new methods to investigate the properties of hydrous minerals at mantle conditions"

PhD project title:

Lab based seismic velocity measurements of antigorite and phase A at upper mantle conditions.

 Project description:

My research involves developing lab based techniques to carry out high pressure and temperature seismic velocity mineral physics experiments in a Paris-Edinburgh cell. Once I have developed the method the aim is to then apply it to studying antigorite and other hydrous minerals at upper mantle conditions. 

Antigorite in subducting oceanic plate undergoes a phase transition at upper mantle conditions, in relatively "hot" settings antigorite transforms into forsterite, enstatite and water. This water is released into the overlying mantle wedge, causing melting and thereby volcanism in the overlying crust. In relatively "cool" settings however, antigorite transforms into enstatite and phase A, the latter of which is a hydrous mineral and thus water is retained in the slab as it continues to subduct. This is thought to be the main process by which water is introduced into the lower mantle. Better understanding of the mineral physics properties of these phases is therefore vital to creating a clearer picture of the Earth's water cycle.