Minerals and rocks

The aim of this course is to introduce the concepts and tools needed to observe and describe magmatic and metamorphic rocks, understand their genesis and appreciate their importance in the geosciences.

The course begins with an introduction to the concepts of mineralogy (crystallography, crystallochemistry) and the tools needed to identify the constituent minerals of magmatic and metamorphic rocks, both macroscopically and microscopically.

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

Two field trips in the Montpellier region will be proposed to illustrate and complete the lessons: the first will be devoted to volcanism in the Hérault valley (D'Agde au Salagou), the second to magmatic and metamorphic activity in the Cévennes.

Identify the main minerals in magmatic and metamorphic rocks and understand the conditions of their formation. Identify the main magmatic and metamorphic rocks and understand the conditions of their genesis.

Basic knowledge of chemistry: periodic classification of elements and physico-chemical properties of chemical elements. Basic notions of mineralogy and crystallography (definition of a mineral, what it's made of, what properties enable it to be identified, recognition of common minerals).

Continuous assessment. During the semester, students will be assessed on 3 tests to evaluate the practical and theoretical knowledge acquired in lectures, practical work and in the field:

- a test on mineralogy accounting for 40% of the final mark,

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

- a test on metamorphism accounting for 30% of the final mark.

• Synthetic description of the concepts covered in CM :

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

CM2: mineralogy: silicate systematics. Presentation of the major groups of silicates and focus on a few silicates illustrating the role of atomic-scale structuring on 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

• Summary description of practical sessions and number of hours for each session

Practical 1: Mineralogy. Reminder of the physical properties of minerals, enabling them to be identified. Macroscopic recognition of silicates (quartz, micas, amphibole, pyroxenes, garnets, olivine, metamorphic silicates).

Practical 2: Macroscopic recognition of silicates. Work on the atomic structures of a few silicates to illustrate the course (quartz, olivine, micas).

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

Practical exercise 4: Introduction to the optical microscope: using analyzed polarized light.

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/manips covered during your field trip(s) and details of destinations/sites

Outing 1: Volcanism in the lower Hérault valley: Baumes volcano, Lézignan-la-Cèbe flows, Cap d'Agde volcano and Conque beach. The aim of the outing is to illustrate the basaltic volcanism that prevailed in the lower Hérault valley during the Quaternary era. Through field observation of outcropping volcanic edifices, the aim is to highlight different eruptive styles (phreatomagmatism, strombolian dynamism, lava flow structuring). The aim is also to reflect on the origin of magmas by observing outcropping rocks.

Outing 2: Metamorphism in the Cévennes: Arres, Col de la Barrière, Dourbies.

The main aim of this outing is to identify the metamorphic rocks and structures outcropping in the Cévennes (greenschists, metamorphic dolomites, cordierite and andalusite schists) and to reconstruct the emplacement history of these metamorphic rocks. A 2km section will be cut between Col de Rhodes and Dourbies to characterize the metamorphism associated with the emplacement of the Saint-Guiral-Liron granitic pluton.

• Macroscopic recognition of the main minerals in magmatic and metamorphic rocks
• Understand the basic operating principle of a polarizing optical microscope and how to use it to identify common minerals in polarized and polarized-analyzed light.
• Identify the main types of magmatic and metamorphic rock and associate them with geological contexts.
• How to read a geological map
• How to read a landscape and construct an outcrop drawing