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Dr.-Ing. Guillaume Desbois

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curriculum vitae

Education

2003 / 2006: PhD Mineralogy - Earth Sciences, LMTG-OMP, UMR 5563; Toulouse, France

2002 / 2003: Post graduate (DEA) Earth Sciences and Environnement, P. Sabatier University; Toulouse, France

2001 / 2002: Graduate (Maîtrise) Earth and Universe Sciences, C. Bernard University; Lyon, France

2000 / 2001: Formation for Physic-Chemistry teaching, University of Burgundy; Dijon, France

1999 / 2001: BSc in Applied Physics, Dublin City University; Ireland

1998 / 1999: B.A. (Licence) Physical Sciences, University of Burgundy; Dijon, France

1996 / 1998: Two years university degree (DEUG) in Sciences of matter, University of Burgundy; Dijon, France

1995 / 1996: General Certificate of Education in Natural Sciences, B. Palissy high school; Gien, France

Research experience

2001 / 2002: MasterI-Thesis:
MgSiO3-Perovskite: equation of state at low temperature
Daniel I., Laboratoire de Dynamique et de la lithosphère, Ecole Normale Supérieure / UMR 5590 ; Lyon , France
Diffraction X measurement performed in diamond cell at ESRF (Grenoble, France) under a pressure of 22 GPa and at 10K suggest a distortion of the crystal structure at 10K and led to think about a possibility of phase transition of MgSiO3-perovskite near 0K.

2002 / 2003: MasterII-thesis:
Measurement of profile of oxygen diffusion in natural diopside single crystal from Adirondack Mountains (NY, USA) - Ionic microprobe measurement and modeling.
Ingrin J., LMTG-OMP, UMR 5563 ; Toulouse, France
Measurement of oxygen diffusion profile by ionic microprobe associated to measurement of Al, Si profile by electron microprobe show that diopside single crystals exhibits, at least, two stages of crystallization in relation to thermal history experienced by the massif of Adirondack. A preliminary oxygen diffusion modeling has been studied in the aim to constrain the cooling rate of these diopside after the granulite metamorphism.

2003 / 2006: PhD-Thesis:
Numerical 3D modeling of atomic diffusion in minerals and applications to the study of hydrogen and oxygen isotopes and Al-Si.
Ingrin J. and Jaoul O., LMTG-OMP, UMR 5563; Toulouse, France
My thesis presents a 3D numerical modeling (finite differences) which can simulate atomic diffusion in single crystals. This new tool allows: to simulate anisotropic diffusion, a large choice of crystal shapes, any initial distribution of concentration, any concentration at surface as a function of time and any temperature change as a function of time. The 3D modeling has been applied to four cases of study : three of them deal with experimental hydrogen diffusion in diopside, lawsonite and tourmaline, the fourth deals with Al-Si and O natural diffusion profiles in diopsides from Adirondacks mountains (NY, USA). These studies illustrate the power of the 3D modeling developed for the description and the interpretation of diffusion profiles. This new tool will be very useful for the interpretation of detailed zonations at grain scale measured by modern analytical techniques.

2006 – recent: Post-doc
Deformation mechanisms and rheology of salt glaciers
Geologie-Endogene Dynamik; Aachen, Germany
Salt glaciers which flow downhill from extruded mountains of Halite (NaCl) have played a major role in the evolution of many sedimentary basins. Halite in these extraordinary structures is much softer than halite in deep subsurface, and it deforms to very large strains by solution precipitation creep activated by the small grain size and traces of water in the grain boundaries. The central aim of this research project is to quantify the deformation mechanisms of Halite in active salt extrusions in Iran, and Oman, by integrating analyses at two different scales.
At the scale of the grain boundaries (nm) samples will be studied by a number of different methods in a high resolution cryogenic SEM, which allows stabilization of the water films in the grain boundaries at 77K, in situ sample preparation by ion-beam-excavation and observation of the frozen fluid at high resolution, combined with microchemical analysis with EDX. We are studying grain boundaries from actively deforming Halite, and also investigate how rainwater penetrates the salt mass by laboratory experiments followed by CRYO-SEM. This will allow us to test the different models for grain boundary structure in solution-precipitation creep, which have been subject of much controversy for the past twenty years. At the scale of grains (mm) samples are studied by transmitted light microscopy of gamma-decorated (blue) thin sections, subgrain size paleopiezometry of polished and chemically etched samples using reflected light microscopy and orientation imaging using EBSD and Helium permeability measurements.

2007 – recent: Post-doc
In-situ investigation of the meso-porosity in wet clay rich geomaterials
Geologie-Endogene Dynamik; RWTH, Aachen, Germany
In fluid-filled porous geomaterials, fluid-rock interactions have important effects on their physical and chemical properties. Though the bulk expression of these properties are relatively well known for a number of geomaterials, the relation between nanostructures and macroproperties are poorly understood for a complete understanding of the fluid-rock interactions. Thus, one of the present challenges in experimental geosciences is to directly characterize the structures of the porous media at the nano scale. However, some geomaterials like clay or shale are so fluids-sensitive that investigations on dried samples, required for conventional electron microscopy imaging, are proscribed. For instance, one new alternative for geosciences is to use the cryo-SEM technology which combines the vitrification of the in-situ fluids to stabilize the microstructures and the SEM imaging at high resolution. In addition, the development of ion milling tools, like FIB, directly embedded into the SEM chamber allows the preparation of high quality polished cross-sections suitable for high-resolution imaging. The FIB-cryo-SEM therefore offers a powerful combination for direct and in-situ investigations of the elusive structures in geomaterials at pore scale.

2008 – recent: Post-doc
Ar-beam cross sectioning and SEM Imaging porosity in sandstone tight gas reservoir
Geologie-Endogene Dynamik; RWTH, Aachen, Germany
Extracting value from tight gas reservoirs, which contain large accumulations of hydrocarbons, represents a challenge for the entire oil industry to give a substantial boost to the world’s reserves. The development of new technologies to enhance tight gas reservoir productivity is strongly dependent on a high-resolution understanding of the porosity. Numerous methods are now available to characterize sandstone cores. However, the pore space characterization at pore scale remains difficult due to the fine pore size and delicate sample preparation, and has been mostly indirect until now. Thus, we propose a new alternative method combining high resolution SEM and argon ion beam cross sectioning (BIB, Broad Ion Beam) to prepare smooth and damage free surfaces. The combination of Ar-beam cross-sectioning facility and high-resolution SEM imaging has the potential to result in a step change in our understanding of porosity, its morphology, spatial distribution and evolution, as well as bringing unprecedented clarity, resolution and predictive reliability.

2009 – recent: Post-doc
In-situ investigation of porosity and microstructures in SAFOD samples (San Andreas Fault, USA)
Geologie-Endogene Dynamik; RWTH, Aachen, Germany
The SAFOD drilling project committee gives us recently the unique opportunity to apply the BIB-cryo-SEM techniques on preserved samples from the active San Andreas Fault Gauge in order to make the role of the porosity in the mechanical behavior of this active fault zone clearer.

Teaching experience

2008: Field trip supervisor at RWTH Aachen University
Geologie-Endogene Dynamik; Aachen, Germany Organization and student support, „Tektonik für anfanger“, Comblain au Pont, Belgium

2008: Part-time lecturer at RWTH Aachen University
Geologie-Endogene Dynamik; Aachen, Germany Lectures in microtectonics

2004 / 2006: Part - time lecturer at Toulouse University
Université Paul Sabatier ; Toulouse, France "Chemical alteration of rocks", "Extern cycle", "Isotopy in geology" and "Oceanic cycles": Bachelor/master.

2005 / 2006: Scientific activity leader for Haute Garonne department
Association "La main à la pâte" ; Toulouse, France Promote scientific approach at elementary school and college. Popularization and diffusion of Earth sciences, especially for earthquakes and volcanology

2000 / 2002: Part - time lecturer for private high schools
"Inter maths"; Dijon and Lyon, France Lectures in mathematics, physics and chemistry

projects

Competences:

• Experimental diffusion, mineralogy
• Salt and clay microstructures. Gamma irradiation
• Rocks deformation
• Microtectonics
• Cryo-SEM
• Electron microprobe
• Ion microprobe
• IR Microscopy
• Modeling, Finite Element Method
• Programming
• Team worker
• Sociable, open-minded
• Rigorous
• Autonomous
• Fluent speaker
• Carefully done drafting
• Presentation and summarizing qualities
• Capacity for leading assembly