PhD position on the role of metamorphic fluid release on the generation of deep earthquakes

Main host institution: Institut des Sciences de la Terre de Paris (ISTeP), UPMC, France

Secondement Institution: Department of Earth, Environmental and Life Sciences (DISTAV), University of Genova, Italy

The Institut des Sciences de la Terre de Paris seeks to appoint a PhD student in petrology, geochemistry and experimental. The successful applicant will work in a multi-­‐disciplinary environment in close collaboration with Anne Verlaguet and Loïc Labrousse in Paris, and Laura Federico in Genoa.

Even if fluid influx or production is often mentioned as a possible mechanism for triggering earthquakes at depth, kinetics and mechanical impact of relevant reactions (linked to eclogitization, eclogite or serpentine dehydration) are still mostly unconstrained. The estimate of both their spatial and temporal characteristic wavelengths and the triggering parameters allowing earthquake nucleation however remains a preliminary issue for implementation of dehydration reactions into realistic thermo-­‐mechanical models for subduction dynamics.

This study will focus on selected examples of paleoseismicity markers (ie. pseudotachylites, eclogite breccias) in the field, at the vicinity or within isolated fragments returned along the fossil plate interface in the Western Alps (Mont Viso), Ligurian Alps (Voltri), and Franciscan Complex (California) in order to constrain their spatial extent, recurrence, and the chief controlling parameters. Trace elements and isotopic compositions of breccia minerals / pseudotachylite will be used to constrain the source of fluid associated with the seismic activity.

In the laboratory, HP-­HT experiments (piston cylinder) will be designed to test the hypotheses derived from field observations. The kinetics of eclogite dehydration will be characterized with in-­‐situ reaction progress monitoring (synchrotron), as a function of both initial lithology and external fluid amount and composition. Trace element redistribution (among reactants / products / trapped fluids) during dehydration reactions will be studied. The kinetics of eclogite fracturing associated with its dehydration will then be studied in HP-­‐ HT-­‐deviatoric stress experiments (Griggs type), as a function of the triggering parameters characterized in the static experiments (fluid amount, composition, reaction progress).

Candidates must hold an MSc in Earth Sciences or related discipline. Experience and interest in petrology, geochemistry, structural geology and high-­pressure experimental petrology is highly advantageous.

The Université Pierre et Marie Curie (UPMC) is located in the heart of Paris Latin Quarter. Paris is a very liveable city and one of the largest cultural centers in Europe. The Institut des Sciences de la Terre de Paris is a key player in the dense network of Earth Science institutes in Paris. As part of UPMC, it also belongs to the “PRES Sorbonne Universités”, a center of excellence gathering several Parisian scientific institutions. The PhD candidate will also spend 3-­‐6 months in the Department of Earth, Environmental and Life Sciences at the University of Genoa, working with Laura Federico in a well-­‐established group of structural geologists and high-­‐pressure petrologists. The PhD candidate will also collaborate with Marcos Moreno (GFZ Potsdam, Germany) and Thomas Pettke (University of Bern, Switzerland).

For further information, please contact Anne Verlaguet (anne.verlaguet@upmc.fr) or Laura Federico (federico@dipteris.unige.it).

Starting date is expected between March and April 2014.

New deadline to apply: Feb 15th, 2014.