Minerals and rocks

The objective of this course is to introduce the concepts and tools for observing and describing magmatic and metamorphic rocks, to understand their genesis and to appreciate their importance in the geosciences.

The course will begin with an introduction to the concepts of mineralogy (crystallography, crystallochemistry) and to the tools needed to identify the constituent minerals of magmatic and metamorphic rocks, both on a macroscopic and microscopic scale.

The different types of magmatic and metamorphic rocks will then be exposed and placed in the geodynamic contexts in which they were formed.

Two field trips in the Montpellier area will be proposed to illustrate and complete the lessons: the first trip will be devoted to the volcanism of the Hérault valley (from Agde to Salagou), the second will be in the magmatic and metamorphic domain in the Cévennes.

Know how to identify the main minerals of magmatic and metamorphic rocks, know their conditions of formation, identify the main magmatic and metamorphic rocks and know their conditions of genesis.

Basic knowledge of chemistry: periodic classification of elements and physicochemical properties of chemical elements. Basic knowledge of mineralogy and crystallography (definition of a mineral, what is it made of, what are the properties allowing to identify them, recognition of common minerals).

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

- a test on mineralogy counting for 40% of the final grade,

- a test on magmatism accounting for 30% of the final grade

- a test on metamorphism counting for 30% of the final grade.

• Synthetic description of the concepts covered in CM:

CM1 : mineralogy. Notions of crystallochemistry : how is a crystal built ? From the properties of the elements to the construction of a silicate (Pauling's rules).

CM2 : mineralogy : silicate systematics. Presentation of the main groups of silicates and focus on some silicates illustrating the role of the structuring at the atomic scale on the physical and chemical properties.

CM3: Magmatic Petrology: Classification of magmatic rocks, structure and nature of the mantle, partial melting and fractional crystallization processes.

CM4: Magmatic petrology: physical properties of magmas, eruptive dynamics and styles, magmas in their geodynamic context.

CM5: metamorphic petrology

CM6: metamorphic petrology

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

TP1 : Mineralogy. Reminder of the physical properties of minerals allowing their identification. Macroscopic recognition of silicates (quartz, micas, amphibole, pyroxenes, garnets, olivine, metamorphic silicates)

TP2 : Macroscopic recognition of silicates. Work on atomic structures of some silicates to illustrate the course (quartz, olivine, micas).

TP3 : Initiation to the optical microscope : use of polarized light without analysis.

TP4 : Initiation to the optical microscope : use of polarized light analysis.

TP5: Macroscopic and microscopic recognition of volcanic rocks.

TP6 : Macroscopic and microscopic recognition of plutonic rocks.

TP7: Macroscopic and microscopic recognition of metamorphic rocks MP/MT.

TP8: Macroscopic and microscopic recognition of HP/HT metamorphic rocks.

• Description of the themes/manipulations addressed during your field trip(s) and details of the destinations/sites

Field trip 1 : Volcanism of the lower Hérault valley : Baumes volcano, Lézignan-la-Cèbe flows, Cap d'Agde volcano and Conque beach. The purpose of the outing is to illustrate the basaltic volcanism that prevailed during the quaternary era in the lower Hérault valley. It is a question of highlighting, through field observation of volcanic edifices at the outcrop, different eruptive styles (phreatomagmatism, strombolian dynamism, structuring of lava flows). It is also a question of reflecting on the origin of magmas through the observation of rocks at the outcrop.

Output 2: Metamorphism in the Cevennes: Arres, Col de la Barrière, Dourbies.

During this outing, it will be essentially a question of identifying the metamorphic rocks and structures at the outcrop in the Cevennes (green schists, metamorphic dolomites, cordierite and andalusite schists) and of reconstructing a history of the setting of these metamorphic rocks. A section of about 2km will be realized between the Rhodes pass and Dourbies in order to characterize the metamorphism linked to the setting of the Saint-Guiral-Liron granitic pluton.

• Know how to recognize the main minerals of magmatic and metamorphic rocks on a macroscopic scale
• Know the basic principle of operation of a polarizing optical microscope and how to use it to identify common minerals in polarized and polarized-analyzed light.
• Know how to identify the major types of magmatic and metamorphic rocks and know how to associate them with geological contexts.
• How to read a geological map
• Know how to read a landscape and construct an outcrop drawing