Geochemistry

This course unit aims 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 address the concepts of compatible and incompatible elements, partition coefficients, geochemical equilibria and fractionation, and element mobility. The geochemistry of major and trace elements will be studied to understand magmatic processes (partial melting, fractional crystallization) and surface processes (water and material transfer and flow; weathering and water-rock interactions). Radiochronology and the 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). Stable O and C isotopes will be studied more specifically in order to characterize the origin of atmospheric fluxes and trace the various processes involved in the water cycle at the hydrosystem scale. 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

Understand the chemical properties of minerals, rocks, and fluids (magma, water) and their behavior during deep and surface transfer processes within different terrestrial reservoirs (atmosphere, hydrosphere, lithosphere, asthenosphere).

Recommended prerequisites:

Basic knowledge of geology, chemistry, and mineralogy.

Continuous assessment. Students will be assessed during the semester on three tests evaluating the practical and theoretical knowledge covered in lectures, tutorials, and practical sessions.

• Brief description of the concepts covered in CM: 1x2 hours and 12 x 1.5 hours

CM1 (2 hours, Fleurice): Introduction to geochemistry

CM2 (Fleurice): Geochemical classification of elements. Major, minor, and trace elements. Composition of the different layers of the Earth.

CM3 (Fleurice): Concepts of compatible/incompatible elements – sharing coefficient

CM4 (Fleurice): Geochemical equilibria and fractionations

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

CM6 (Fleurice): Radiochronology and radiogenic isotopes

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

CM8 (Christelle): Introduction to water geochemistry (carbonate and silicate dissolution).

CM9 (Christelle): Introduction to water geochemistry (carbonate and silicate dissolution).

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

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

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

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

• Brief description of tutorial sessions and number of hours associated with each session

TD 1: Calculating the structural formula of minerals based on geochemical analyses.

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

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

TD 4: Use of stable water and carbon isotopes to characterize the origin of atmospheric fluxes 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 atmospheric contributions, contributions from water-rock interactions, and anthropogenic impacts on surface water

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

• Brief description of practical sessions and number of hours associated with each session

3-hour practical: analytical techniques/laboratory visits: powder and solution analyses of rocks (XRD, XRF, MC-ICP-MS) and in situ (microprobe and La-ICPMS). Visits to laboratories at GM, HSM, and OSU-OREME.

- Understand the geochemical properties of major, trace, and isotopic elements.

- Know how to characterize and explain their behavior in deep and surface transfer processes within different terrestrial reservoirs

- Ability to work independently, describe, write, summarize.