T4. Sedimentary transfers, diagenesis and resources

 

The object of this theme is the reconstruction of soil erosion, the transfer of sediments and contaminants at the earth’s surface, their transport to sedimentary basins and all of the transformations that occur during their burial. The methodological approach adopted is varied and includes sedimentology, geochemistry, magnetic properties, measurement of radioactive tracers, etc. This approach allows us to extract significant information, at various time scales from different types of natural samples (sediments, water, rocks, minerals, etc.). The information retrieved throws light on the formation conditions (deposition conditions, sedimentary environment, hydrolysis conditions, etc.), on export conditions (erosion, percolation, fracturing, burial, etc.) and on long-term transformations (burial diagenesis, modification of petro-physical properties, fluid-rock interactions, etc.) The studies focus on current environments (transfer of particles and contaminants, evolution of carbon in the soil and in aquatic environments, etc.) and past environments, landscape evolution, palaeoclimate and the accumulation of resources within reservoirs (hydrocarbons, metals, materials).

 

Sub-themes and associated methods:

 

T4.1 – Erosion, chemical alteration and sedimentary dynamics in the past

  • Climate changes and sedimentary dynamics [Laser granulometry, X-ray diffractometry, SEM, Environmental magnetism, Cathodoluminescence microscopy]

  • Clay sedimentology [X-ray diffractometry]

  • Reconstruction of marine currents [Laser granulometry, X-ray diffractometry, SEM, Environmental magnetism]

 

T4.2 Diagenetic evolution of sediments. [X-ray diffractometry, SEM, Cathodoluminescence microscopy, Water porosimeter, Optical microscopes]

  • Characterisation of fluid-mineral interactions [X-ray diffractometry, SEM, Cathodoluminescence microscopy, Water porosimeter, Optical microscopes]

  • Characterisation of mineralogical transformations [X-ray diffractometry, SEM, Cathodoluminescence microscopy, Optical microscopes]

  • Characterisation of the transformations of organic matter [EA-IRMS]

  • Relationships between deposition environments and diagenetic evolution [X-ray diffractometry, SEM, Cathodoluminescence microscopy, Optical microscopes]

 

T4.3 Study of the mechanisms and chronology of the physico-chemical processes leading to the formation of exploitable deposits [X-ray diffractometry, SEM, Cathodoluminescence microscopy, Water porosimeter, Optical microscopes]

  • Dating of newly-formed phases [SEM, Cathodoluminescence microscopy, Optical microscopes, LA-ICPMS-HR]

  • Characterisation of the geometry of sedimentary bodies and the link with porosity and permeability properties. [SEM, Cathodoluminescence microscopy, Optical microscopes]

 

T4.4 – Current soil erosion – transfer of particles and contaminants - Dynamics of environmental change

  • Chronological reconstruction of pollution and sedimentation [Gamma-Ray spectrometry, ICP-QMS]

  • Radio-isotopic chronometry of particle transfer processes [Gamma-Ray spectrometry]

  • Soil carbon dynamics and vulnerability [14C, 13C, 15N]

  • The dynamics and fate of organic matter in aquatic environments (rivers, seas and oceans) [14C, Tritium, 13C]

  • Landscape geomorphology and evolution (valley formation, etc.) [Gamma-Ray spectrometry, ICP-QMS]

  • Fate and persistence of artificial 14C emissions. [14C]

  • The dynamics of natural and anthropogenic magnetic particles in river systems [Environmental magnetism]

  • Analytical tools (associated themes):

  • Lithological thin-section workshop (preparation of thin-sections of rock and unconsolidated sediments) (T4.2, T4.3)

  • Métromesures impregnation cell (T4.2, T4.3)

  • Optical microscopes (T4.2, T4.3)

  • Cathodoluminescence microscopy (T4.1, T4.2, T4.3)

  • X-ray diffractometry (clay-, rock-, and sediment mineralogy) (T4.1, T4.2, T4.3)

  • Wet-phase laser granulometry (T4.1)

  • Scanning electron microscope equipped with an EDS sensor (T4.1, T4.2, T4.3)

  • Cryogenic magnetometers, Magnetic susceptibility test bench, Micromag (AGM2900), Curie scale (T4.1, T4.4)

  • Low-background gamma spectrometry (T4.4)

  • EA-IRMS (T4.2, T4.4)

  • Trace and major element ICP-QMS (T4.4)

  • MC-ICPMS of Sr isotopes (T4.4)

  • ECHoMICADAS 14C (T4.4)