2020-10- Postdoctoral position: Hydrothermal dolomitization

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Postdoctoral position: What controls hydrothermal dolomitization? Insights from dynamic experiments under x-ray tomography.

Scientific context

Fluid-mediated mineralogical replacement is a chemical transformation phenomenon that affects rocks in sedimentary, metamorphic, and even atmospheric conditions. By transforming a solid phase into a more stable one, replacement leads to changes in the structural integrity and permeability of the rock that can have dramatic consequences for earthquake hazards, reservoir quality, civil engineering, while being one efficient way for cycling elements within rocks.

A striking example of such transformation is the hydrothermal dolomitization of limestones, i.e. fluid-mediated stoichiometric substitution Casolid ↔ Mgfluid replacing CaCO3 with dolomite CaMg(CO3)2, creating km-scale geobodies usually related to ore deposits or hydrocarbons, and being very efficient bodies for carbon sequestration.

As for numerous hydrothermal reactions, various chemo-physical models built from chemical analysis and experiments in analogous replacement compete to explain this mineralogical transformation. Yet, relevant comparison to natural systems remains limited, and the way to explain the creation of large dolomite geobodies remains unexplained. Consequently, we are far from grasping the full potential of replaced rocks for societal problematics such as georesources or greenhouse gas cycling.

Only recently has dolomitization been successfully recreated in laboratory under a reasonable timescale, a few hours to a week according to the fluid reactivity.

This project proposes to use non-destructive imagery methods (xCT) coupled with hydrothermal reactors to reproduce dolomitization in-situ. The impact of fluid reactivity on the expression and propagation of the reaction front will be specifically addressed. The successful experiment will allow to quantify and describe the microstructures related to replacements (pores, fractures, grains orientation and size) to help unravelling how dolomitization can propagate in nature.

 

Working conditions

Host laboratory :  LFCR

Scientific team: The candidate will be part of the CRG (Characterization of Geological Reservoirs) team

Localisation : Université de Pau et des Pays de l’Adour (UPPA), Pau, France

Duration: 18 months

Starting period: January 6th, 2021 - or otherwise agreed

Work load (in percentage): 100 %.

Main missions:

  • Design and carry experimental work from published protocols in ex-situ reactors
  • Design and conduct in-situ replacement work
  • Acquire and treat 4D xCT data
  • Writting and presenting results throught peer-reviewed publications and conferences.
  • The contract includes 64 hours of teaching that can be arranged to be done in English, this part will be starting in September 2021

Monthly gross salary: 2737€

 

Requirements

Diploma required: PhD Title or an equivalent foreign Diploma in the domain of  geology or chemistry, with a strong emphasize either on mineralogical replacement or experimental work.

Desirable skills:

  • Any past experience with carbonate diagenesis and/or 3D imagery would be a plus.
  • Previous experience with either experimental device or xCT will be strongly appreciated.
  • The candidate must be capable of performing research without day-by-day guidance.
  • The work will be carried out in relationship with several scientists and in collaboration with foreign researchers, so good teamwork skills are required.
  • The candidate must be capable of producing reports and manuscripts to be send for publication to international renowned journals. The candidate should also be able to present oral contributions at conferences and present the results in front of sponsors at a general audience level.

English proficiency is compulsory.

 

Application

Applications must be written in English.

Document required:

  • detailed CV (including a list of publications, if applicable)
  • cover letter
  • contact details of at least 2 referees

For more information and for applying for this position, please contact Nicolas Beaudoin, by email at nicolas.beaudoin @ univ-pau.fr

 

 

Application deadline : November 20th, 2020