Geochemistry

The objective of this course is to introduce the concept of chemical element properties, geochemical classification and distribution of major and trace elements in minerals, rocks and fluids. We will approach the notion of compatible and incompatible elements, partition coefficient, geochemical equilibrium and fractionation and mobility of elements. 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; alteration and water-rock interactions). Radiochronology and stable and radiogenic isotope geochemistry will also be addressed to identify the different reservoirs within the Earth, to date rocks and fluids (surface and deep) and to study the geochemical transfers between the different reservoirs (asthenosphere, lithosphere, hydrosphere and atmosphere) Stable isotopes of O and C will be more specifically studied in order to characterize the origin of atmospheric fluxes and to trace the different processes involved in the water cycle at the scale of hydrosystems. Dissolved and particulate geochemical flux budgets in hydrosystems will be addressed in order to understand the dynamics of global terrestrial surface cycles.

Hourly volumes:

CM : 20

TD : 22

TP : 3

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

Recommended prerequisites:

Basic knowledge of geology, chemistry and mineralogy.

Continuous assessment. The students will be evaluated during the semester on 3 tests allowing the evaluation of the practical and theoretical knowledge seen in courses, TD and TP.

• Synthetic description of the 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 the different terrestrial envelopes.

CM3 (Fleurice) : Notions of compatible/incompatible elements - partition 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): Notion of reservoirs - geochemical balance and cycle.

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

CM9 (Christelle): Introduction to water geochemistry (dissolution carbonates, 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. Material balance and global cycles

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

TD 1: Calculation of the structural formula of minerals from geochemical analyses.

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

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

TD 4: Use of stable isotopes of water and carbon to characterize the origin of atmospheric fluxes and some processes of 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 part, from water-rock interactions and from anthropic impact on surface water

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

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

TP 3h: analytical techniques/lab visit: powder and solution analysis of rocks (XRD, XFR, MC-ICP-MS) and in situ (microprobe and La-ICPMS).

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

- Know how to characterize and explain their behavior in the processes of deep and surface transfers within the various terrestrial reservoirs

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