17 May 2024
Job Information
- Organisation/Company
CNRS- Department
Institut des Sciences de la Terre d'Orléans- Research Field
Geosciences
Astronomy
Environmental science- Researcher Profile
First Stage Researcher (R1)- Country
France- Application Deadline
6 Jun 2024 - 23:59 (UTC)- Type of Contract
Temporary- Job Status
Full-time- Hours Per Week
35- Offer Starting Date
1 Sep 2024- Is the job funded through the EU Research Framework Programme?
Not funded by an EU programme- Is the Job related to staff position within a Research Infrastructure?
No
Offer Description
Plate boundary fault zones exhibit a wide range of dynamic behaviours, from aseismic slip to mega-earthquakes. So far, there is no consensus on a model describing the processes controlling these fault behaviours. A possible answer might lie in the properties of smectite, a swelling clay mineral that form the core of many of the fault zones and that is able to adsorb significant amounts of water in-between nanometric interlayers. Despite their potential importance, the thermodynamics of hydration/dehydration reactions in smectite and the connections between these reactions and the fault deformations remain poorly known. These fundamental questions are the heart of the ANR project SMEC funding this Ph.D. position.
The objectives of the SMEC project are: 1) to decipher the thermodynamics of hydration/dehydration in smectite, as a function of the conditions of confining pressure, fluid pressure, and temperature, 2) to link hydration to the mechanical behaviour, and 3) to upscale this coupling between hydration and mechanics to the scale of faults in the perspective of applying it to address large-scale natural examples. These questions will be addressed using a combination of laboratory experiments and numerical simulations from the clay mineral layer to the plate boundary fault.
Within the framework of SMEC (the funding project, see below), the objectives of the present Ph.D. project are twofold. The first goal is to constrain experimentally the conditions of dehydration/hydration in smectite. Experiments of dehydration/hydration reactions will be carried out at ISTO, using a semi-transparent, high-pressure and high temperature vessel at ISTO equipped with in situ XRD monitoring. XRD patterns will be modelled in terms of water layer distribution in smectite interlayer space. The role of the different parameters (Pfluid-Psolid-T conditions, nature of interlayer cation) on the reactions will be assessed. The details of dehydration/hydration reactions will be analysed on the basis of complementary Synchrotron experiments using the same experimental setup.
In a second part, the Ph.D. project will focus on the effect of such hydration/dehydration reactions on smectite mechanical properties. Friction experiments will be carried out in the Paterson rig to analyse the mechanical properties of smectite aggregates. Steady-state friction coefficient, as well as rate-dependence, will be estimated as a function of interlayer water, interlayer cation, temperature and confining/pore pressure. Second, the role of dehydration reactions occurring during deformation to trigger slip instabilities, will also be explored.
These experimental results will then be used as inputs to develop theoretical and numerical approaches of smectite thermodynamics and mechanical properties (not handled in the present position but in other parts of the overall SMEC project).
Requirements
- Research Field
- Geosciences
- Education Level
- Master Degree or equivalent
- Research Field
- Astronomy
- Education Level
- Master Degree or equivalent
- Research Field
- Environmental science
- Education Level
- Master Degree or equivalent
- Languages
- FRENCH
- Level
- Basic
- Research Field
- Geosciences
- Years of Research Experience
- None
- Research Field
- Astronomy
- Years of Research Experience
- None
- Research Field
- Environmental science
- Years of Research Experience
- None
Additional Information
Additional comments
The project will be hosted in the Institute of Earth Sciences of Orléans (https://www.isto-orleans.fr/en/home/ ) at the University of Orléans (http://www.univ-orleans.fr/en ). SMEC project, encompassing the present Ph.D. position, involves a consortium of 7 labs and the recruitment of 3 Ph.D. positions. Regular trainings and scientific discussions between the 3 Ph.D. positions and the scientific partners of SMEC will be organized.
We are looking for a highly motivated student with a strong interest in deformation processes and mineral reactions. The applicant should hold a Master degree (or equivalent) in Earth Sciences or Mechanics.
The application should include a full CV, transcripts of academic degrees, a statement of research interests and the contact information of two potential referees.
- Website for additional job details
https://emploi.cnrs.fr/Offres/Doctorant/UMR7327-MARROU0-046/Default.aspx
Work Location(s)
- Number of offers available
- 1
- Company/Institute
- Institut des Sciences de la Terre d'Orléans
- Country
- France
- City
- ORLEANS
- Geofield
Where to apply
- Website
https://emploi.cnrs.fr/Candidat/Offre/UMR7327-MARROU0-046/Candidater.aspx
Contact
- City
ORLEANS- Website
https://www.isto-orleans.fr/
STATUS: EXPIRED