OVERVIEW

Geochemistry is the study of chemico-physical properties of terrestrial materials in the various aggregation states of matter (crystalline, glassy, liquid and gaseous) and allows the quantitative understanding of chemical reactions and transformation processes of geological systems from a thermodynamic perspective.   

AIMS AND CONTENT

LEARNING OUTCOMES

The aim of the teaching is to provide the basic knowledge on chemico-physical and thermodynamic laws that govern solid-melt-gas phase equilibria and reactivity of Earth materials. Major topics are: i) geochemistry and thermodynamics of crystalline solids (pure solids and solid mixtures); ii) geochemistry of silicate melts and glasses; iii) phase diagrams of petrogenetic interest; iv) geochemistry of aqueous solutions (e.g. Eh-pH and activity diagrams); v) geochemistry of gaseous phases; vi) basic concepts of cosmochemistry and isotopic geochemistry (e.g. age of the Earth, meteorites). Some lectures, tutorials and practice on computational modelling in geochemistry are also included in the course.

AIMS AND LEARNING OUTCOMES

Attendance and participation in the planned educational activities (lectures and laboratory sessions) will enable students to acquire general knowledge for conducting geochemical studies on minerals, rocks, magmas, aqueous solutions and gases in Earth and planetary systems.

Specifically, students will be able to:

• identify, describe and understand chemico-physical properties of matter in its different states (solid, liquid and gaseous)
• understand thermodynamic properties of rock-forming minerals, silicate melts (magmas), aqueous solutions and gases and relate them to their stability conditions and to the main geochemical processes active in the Earth and planetary systems 
• quantify and understand reaction and transformation processes of geological systems from a thermodynamic and chemico-physical point of view
• apply the acquired theoretical knowledge to perform and interpret thermodynamic calculations on crystalline, liquid and gaseous compounds, as carried out during laboratory exercises

PREREQUISITES

The course is particularly beneficial for students who already possess a background in chemistry, physics and/or mathematics.

TEACHING METHODS

Lectures, hands-on tutorials and exercises, computer laboratory activities.

Students who have valid certification of physical or learning disabilities on file with the University and who wish to discuss possible accommodations or other circumstances regarding lectures, coursework and exams, should speak both with the instructor and with Professor Sara Ferrando (sara.ferrando@unige.it), the Department’s disability liaison.

SYLLABUS/CONTENT

The program of the course includes the presentation and discussion of the following topics:

1) GEOCHEMISTRY OF CRYSTALLINE PHASES - Chemical properties of the elements of the periodic table and crystal-chemistry; basic concepts of chemical thermodynamcs (definition of a thermodynamic system; homogeneous and heterogeneous systems; phases and components; equilibrium and disequilibrium; stability and metastability; Gibbs phase rule; Gibbs free energy and chemical potentials; solid-state phase transitions; thermodynamic activity and standard state of reference; Enthalphy, entropy, volume thermal expansion and compressibility, equations of state of crystalline solids); thermochemistry of crystalline solids (isochoric and isobaric heat capacities; Gibbs free energy calculation at high pressure and high temperature conditions; thermodynamic properties and mixing models for ideal and non-ideal binary solid mixtures; structural disorder; excess thermodynamic functions; solvus, miscibility gap and spinodal decomposition).

2) GEOCHEMISTRY OF SILICATE MELTS - Structure-energy properties of multi-component silicate melts (ionic, quasi-chemical and polymeric models; acid-basic properties of molten oxides and Lux-Flood formalism; Toop-Samis polymeric model; effects of pressure and composition on the melting process: Clausius-Clapeyron equation and freezing point depression equation; relations between liquid and glassy state, glass transition; Ghiorso-Carmichael model for complex silicate melts).

3) PHASE DIAGRAMS FOR PETROGENETIC SYSTEMS - Binary phase diagrams with solid-state miscibility and immiscibility (plagioclase and olivine systems; anorthite-diopside system), binary phase diagrams with eutectic points only (kalsilite-nepheline-albite-SiO2) and with eutectic and peritectic points (leucite-sanidine-SiO2), binary phase diagrams with solvus (enstatite-diopside system for pyroxenes; albite-KAlSi3O8 for alkali feldspars); ternary phase diagrams (albite-anorthite-KAlSi3O8, diopside-anorthite-albite and forsterite-enstatite-diopside-SiO2 systems).

4) GEOCHEMISTRY OF AQUEOUS SOLUTIONS - Chemico-physical and thermodynamic properties of H2O; dielectric constant; structural models of liquid water; phase diagram of H2O, supercritic state; water dissociation equilibrium constant, definition of pH and pH scale for aqueous solutions; classification of electrolytes in aqueous solutions; definition of activities, molalities and activity coefficients of electrolytes in aqueous solutions; ionic strenght and Debye-Huckel theory; the "mean salt" method; speciation and method of calculation; hydrolisis and solvation processes; redox conditions, Eh-pH relations and thermodynamic stability of aqueous solutions; Eh-pH diagram of H2O; Eh-pH or predominance diagrams for Ce-O-H, C-O-H, N-O-H, P-O-H,S-O-H, Fe-C-S-Si-O, Mn-C-S-O-H, Cu-C-S-O-H systems; alkalinity, carbonate equilibria; saturation index, solubility product and activity product; affinity to equilibrium in heterogeneous systems; activity diagrams; chemico-physical properties, salinity and chlorinity of seawater.

5) GEOCHEMISTRY OF GASEOUS PHASES - Perfect gases and gaseous mixtures; activity, fugacity, partial pressure, fugacity coefficients; real gases at sub-critical, critical and super-critical conditions; equations of state for real gases (principle of corresponding states, van der Waals equation, Redlich-Kwong equation); reduced parameters and universal chart of gases; solubility of gaseous species in magmas; volcanic gases; fluids in hydrothermal and geothermal systems.

RECOMMENDED READING/BIBLIOGRAPHY

The slides used during lessons and other teaching materials will be available on AulaWeb at the end of each cycle of lessons/laboratory exercises.

Recommended textbooks are:

Ottonello G., (1991) Principi di Geochimica. Zanichelli, Bologna, 708pp. 

Ottonello G., (1997) Principles of Geochemistry. Columbia University Press, New York-Chicester-West Sussex, 894 pp.

TEACHERS AND EXAM BOARD

LESSONS

LESSONS START

https://corsi.unige.it/en/corsi/8763/students-timetable

Class schedule

GEOCHEMISTRY

EXAMS

EXAM DESCRIPTION

Oral exam (see assessment methods)

ASSESSMENT METHODS

The exam will be oral with some parts of thermodynamic calculation to be performed by the students.

Students are recommended to follow updates about COVID-19 on the specific AULA WEB page.

FURTHER INFORMATION

Attendance to lectures is recommended.

Informations for students with a disability certificate can be found at https://unige.it/disabilita-dsa/studenti-disturbi-specifici-apprendimento-dsa, as provided by "Settore servizi per l'inclusione degli studenti con disabilità e con DSA". For further details please also refer to Prof. Sara Ferrando (sara.ferrando@unige.it) as contact person for disabilities at DISTAV.

Ask the professor for other information not included in the teaching schedule.