Geochemistry

The aim of this course is to introduce the concept of chemical element properties, geochemical classification and the distribution of major and trace elements in minerals, rocks and fluids. We will cover the notion of compatible and incompatible elements, partition coefficients, geochemical equilibria and fractionations, and elemental mobility. The geochemistry of major and trace elements will be studied to understand magmatic processes (partial melting, fractional crystallization) and surface processes (water and matter transfers and fluxes; weathering and water-rock interactions). Radiochronology and geochemistry of radiogenic and stable isotopes will also be addressed to identify the different reservoirs within the Earth, date rocks and fluids (superficial and deep) and study geochemical transfers between the different reservoirs (asthenosphere, lithosphere, hydrosphere and atmosphere). More specifically, stable isotopes of O and C will be studied to characterize the origin of atmospheric fluxes and trace the various processes involved in the water cycle at the scale of hydrosystems. Dissolved and particulate geochemical flux balances in hydrosystems will be addressed in order to understand the dynamics of global terrestrial cycles at the surface.

Hourly volumes :

CM: 20

TD : 22

TP: 3

Know the chemical properties of minerals, rocks and fluids (magmas, water) and how they behave during deep and surface transfer processes within the Earth's various reservoirs (atmosphere, hydrosphere, lithosphere, asthenosphere).

Recommended prerequisites :

Basic knowledge of geology, chemistry and mineralogy.

Continuous assessment. During the semester, students will be assessed on 3 tests to evaluate the practical and theoretical knowledge acquired in lectures, tutorials and practical work.

• Synthetic description of concepts covered in CM: 1x2h and 12 x 1.5h

CM1 (2h, Fleurice): Introduction to geochemistry

CM2 (Fleurice): Geochemical classification of elements. Major, minor and trace elements. Composition of different earth envelopes.

CM3 (Fleurice): Notions of compatible/incompatible elements - partition coefficient

CM4 (Fleurice): Geochemical equilibria and fractionation

CM5 (Fleurice): Geochemistry of trace elements in magmatic processes (partial melting, fractional crystallization).

CM6 (Fleurice): Radiochronology and radiogenic isotopes

CM7 (Fleurice): Notion of reservoirs - balance and geochemical cycle.

CM8 (Christelle): Introduction to water geochemistry (dissolution of carbonates and silicates).

CM9 (Christelle): Introduction to water geochemistry (dissolution of carbonates and silicates).

CM10 (Christelle): Stable isotope geochemistry: S, C, 18O-D

CM11 (Christelle): Stable isotopes in the hydrosphere and atmosphere between present and past. Geochemical tracers in paleoclimatology

CM12 (Christelle): Tracing atmospheric flows and processes involved in the water cycle

CM13 (Christelle): Dissolved and particulate geochemical fluxes in hydrosystems. Matter balance and global cycles

• Summary description of TD sessions and number of hours associated with each session

TD 1: Calculation of mineral structural formulae from geochemical analyses.

TD 2: Geochemical modelling of partial melting and fractional crystallization processes.

TD 3: Geochemical cycle - case study (S, CO2, etc.)

TD 4: Using stable isotopes of water and carbon to characterize the origin of atmospheric flows and certain processes in the water cycle

TD 5: Water-rock interaction: geochemical composition of continental waters and links with the geological nature of watersheds

TD 6: Origin of major elements in hydrosystems: estimation of the atmospheric fraction, the fraction resulting from water-rock interactions and the fraction resulting from anthropogenic impact on surface water.

TD 7: Dissolved element fluxes and global balances: the case of the Amazon basin

• Summary description of practical sessions and number of hours for each session

TP 3h: analytical techniques/lab visits: powder and solution analysis of rocks (XRD, XFR, MC-ICP-MS) and in situ (microprobe and La-ICPMS); laboratory visits to GM, HSM and OSU-OREME.

- Geochemical properties of major, trace and isotopic elements.

- Characterize and explain their behavior in deep and surface transfer processes in various terrestrial reservoirs

- Know how to work independently, describe, write and synthesize.