Geochemistry

The objective of this course unit is to introduce the concept of the properties of chemical elements, geochemical classification, and the distribution of major and trace elements in minerals, rocks, and fluids. We will discuss 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 (transfers and fluxes of water and matter; weathering and water-rock interactions). Radiocarbon dating and the geochemistry of radiogenic and stable isotopes will also be covered to identify the various reservoirs within the Earth, date rocks and fluids (both surface and deep), and study geochemical transfers between the different reservoirs (asthenosphere, lithosphere, hydrosphere, and atmosphere). Stable oxygen and carbon isotopes will be studied more specifically to characterize the origin of atmospheric fluxes and to trace the various processes involved in the water cycle at the scale of hydrosystems. The budgets of dissolved and particulate geochemical fluxes in hydrosystems will be addressed in order to understand the dynamics of global terrestrial cycles at the Earth’s 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 transport processes within the various terrestrial reservoirs (atmosphere, hydrosphere, lithosphere, asthenosphere).

Recommended prerequisites:

Basic knowledge of geology, chemistry, and mineralogy.

Continuous, comprehensive assessment. Students will be evaluated throughout the semester via three assessments designed to evaluate the practical and theoretical knowledge covered in lectures, tutorials, and lab sessions.

• Summary of the topics covered in CM: 1 session of 2 hours and 12 sessions of 1.5 hours

CM1 (2 hours, Fleurice): Introduction to Geochemistry

5th Grade (Fleurice): Geochemical classification of elements. Major, minor, and trace elements. Composition of the Earth's various layers.

3rd Grade (Fleurice): Concepts of compatible and incompatible elements – distribution coefficient

CM4 (Fleurice): Geochemical Equilibria and Fractionation

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

CM6 (Fleurice): Radiometric dating and radiogenic isotopes

CM7 (Fleurice): The Concept of Reservoirs—Inventory and Geochemical Cycle.

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

CM9 (Christelle): Introduction to the Geochemistry of Water (dissolution of carbonates and silicates).

CM10 (Christelle): Stable Isotope Geochemistry: S, C, 18O-D

CM11 (Christelle): Stable isotopes in the hydrosphere and atmosphere: Present and Past. Geochemical tracers in paleoclimatology

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

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

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

Assignment 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 Cycles—Case Study (S, CO2, etc.)

TD 4: Use of stable isotopes of water and carbon 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 to the Geological Characteristics of Watersheds

TD 6: Origin of Major Elements in Hydrosystems: Estimation of Contributions from the Atmosphere, Water-Rock Interactions, and Anthropogenic Impacts on Surface Water

TD 7: Fluxes of Dissolved Substances and Overall Balances: The Case of the Amazon Basin

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

3-hour lab session: analytical techniques/lab tour: powder and solution analyses of rocks (DRX, XFR, MC-ICP-MS) and in situ analyses (microprobe and La-ICP-MS). Tour of the laboratories at GM, HSM, and OSU-OREME.

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

- Be able to characterize and explain their behavior in deep and surface transport processes within various terrestrial reservoirs

- Be able to work independently, describe, write, and summarize.