Structural geology

This course introduces the fundamentals of Structural Geology at undergraduate level. The teaching will focus on the analysis of the various objects and deformation processes present at all levels of the earth's crust. Rock deformation will be studied using examples from the field (photos and geological maps), samples, thin sections and experiments. The main focus will be on the analysis of deformation processes (brittle and ductile), as well as the associated structural objects. The interpretation of these structures will be addressed in terms of tectonic regimes. Techniques for structural measurements and stereographic projections of objects encountered in the field will be taught. Structural analysis will range from small-scale microscopy to large-scale study of 1:⁵⁰,000 geological maps and satellite photos of deformed domains.

Hourly volumes:

• CM: 6h
• TD : 6h
• Practical work: 6h

The aim of this course is to provide students with fundamental notions of structural geology, practical know-how and mastery of tools for acquiring, processing and interpreting field data. Students will understand how to approach the analysis of naturally deformed objects at all scales, and how to characterize a deformation regime from natural field data.

• HAT102T Geology
• HAV213T Earth evolution and regional geological history

Recommended prerequisites :

• HAT202T Experimentation and terrestrial dynamics

100% Continuous assessment: 5 marks for CM, TD and TP.

Synthetic description of the concepts covered in CM :

• Stereographic projection techniques: theory, notation systems, transfer techniques: examples of planes and lines.
• Analysis and interpretation of tectonic objects and processes (part 1): brittle deformation
• Analysis and interpretation of tectonic objects and processes (part 2): ductile deformation
• Deformation micro-mechanisms: cataclastic creep, dynamic recrystallization and diffusion. Shear criteria.

Summary description of TD sessions and number of hours associated with each session

• Stereo reports 1/2: objects and axes of principal stresses - Brittle deformation: styloliths, tension cracks, faults and striations. Tilting (rotation) of layers. Links with tectonic regime. 1h30.
• 2/2 stereo reports: objects and axes of main deformation - Ductile deformation: schistosity and lineation; superposition and crenulation; folds, axes and axial planes; flank tilting around the fold axis. 1h30.
• Geological map of Lavelanet or Mas-d'Azil: cross-section from map extracts. 3h.

Synthetic description of TP sessions and number of hours associated with each session

• Measurements of plans on campus, positioning and transfer of data to map; 1st use of compass and clinometer. 1h30 (Homework => Stereographic projections).
• Micro-optics: 4 thin sections of deformed rock to observe (3 granites: deformation at BT, MT and HT, + 1 micaschist) => annotated drawings of two thin sections, + explanations. 1h30.
• Geological maps of Ornans or Pontarlier: structural diagram and cross-section. 3h.

No land

• Understand the mechanisms of crustal rock deformation at all depths.
• Recognize, analyze and interpret a geological structure in the field, on a map or under a microscope.
• Know how to measure structural objects in 3D and master stereographic projection techniques (2D conversion).
• Master the techniques of reading and analyzing geological maps.