Rates of metamorphic crystal growth: insight from elemental heterogeneities at the crystal scale

Durée: Possiblement > 6 semaines - à définir // Début du stage: dès que possible

Water liberated deep down in subduction zones through metamorphic dehydration reactions affects the physical parameters governing rocks’ behaviour (crystals & inter-granular medium) through favouring stress release. Therefore, the kinetic of metamorphic reactions will define the rate at which those parameters change through time. Although there is a collection of evidence indicating that crystallization in igneous system can occur over rather short period of times (10’s to 100’s of years) there is, up to date, no clear path to extract a duration of crystallization in metamorphic systems. A new approach developed by the supervisors of this project enable to do so. This cutting-edge approach has yielded preliminary results of duration in the order of weeks for crystallization of oscillatory zones in ultra-deep garnet from Dora Maira (> 30 kbar). The aim of this project is to expand these new results to deeper PT conditions where serpentine breaks down to form metamorphic olivine and integrate these results within a broader framework which will include geophysical observations, such as slow slips and tremors.

A solid background in metamorphic petrology and mineral geochemistry is expected. Lastly, it should be stressed that the selected student will have to make his/herself familiar with (i) an emerging (and thus unsettled) field of research, (ii) state of the art analytical LA-ICP-MS protocol and (iii) the physics of crystal growth medium.