OVERVIEW

The Petrography course provides the theoretical and applied foundations for the recognition, classification, and interpretation of igneous, sedimentary, and metamorphic rocks, with particular attention to the geological processes that determine their origin and evolution.

The course combines lectures, practical laboratory sessions, and field activities in order to develop operational skills useful for the study of geomaterials and for the interpretation of the geological landscape.

AIMS AND CONTENT

AIMS AND LEARNING OUTCOMES

The course provides a description of the Earth's interior, offering knowledge on the petrogenesis of igneous, sedimentary, and metamorphic rocks. Once students have acquired the tools to apply genetic criteria in distinguishing the three main rock groups, the program introduces classification diagrams to assign the correct nomenclature to rocks.

Classroom exercises using rock collection samples are designed to demonstrate, clarify, and apply the analytical procedure for rock identification. The integration of these steps leads to the correct naming of rocks using scientifically validated classification diagrams.

A further specific learning objective within the field of natural sciences is to understand the driving forces behind lithospheric dynamics and the relationship between rock textures and their evolution within the endogenic and/or exogenic cycle. Students should be able to discuss the relevance of a rock to specific petrogenetic environments, based on its texture, mineralogical composition, and, where possible, chemical composition.

Finally, a key learning goal of the course is to equip students with the tools necessary to correctly recognize, interpret, and classify rocks—essential skills for successfully following third-year Earth Science courses, which are closely related and built upon this foundational knowledge.

PREREQUISITES

The Petrology course requires prior knowledge in inorganic chemistry and mineralogy.

TEACHING METHODS

Classroom lectures. The theoretical component of the course is delivered through face-to-face lectures supported by multimedia presentations (PowerPoint), digital teaching materials, and guided consultation of web resources of scientific interest.

Practical sessions. Practical activities are based on the observation, description, and discussion of specimens from the DISTAV teaching rock collection. Sample analysis is carried out through guided demonstrations and direct interaction with students, also with the support of 3D projection systems when necessary.

Indoor laboratory sessions take place in laboratories equipped with petrographic microscopes and appropriate technical lighting. Students are required to provide themselves with a 10× hand lens and a steel point for performing the scratch test, which is used for the comparative assessment of mineral microhardness.

The course also includes field excursions to areas of particular geological interest in Liguria, focusing on the study of Apennine and Alpine ophiolites. Field activities will enable students to apply the rock classification criteria presented during the course and to develop skills in the collection, interpretation, and cartographic representation of geological and lithological data.

SYLLABUS/CONTENT

Course Outline

Introduction

Overview of the composition and internal structure of the Earth. Fundamentals of global tectonics and Earth dynamics, with particular emphasis on endogenous and exogenous processes governing the evolution of the lithosphere.

Petrogenetic Processes

a) The Magmatic Process

Definition of magma and silicate melt; chemical and physical properties of magmas and mechanisms of melt generation. Magma dynamics within the Earth’s crust, including ascent and emplacement processes. Cooling and solidification of melts, with particular focus on magmatic crystallization processes.

b) The Sedimentary Process

Processes of weathering, erosion, transport, sedimentation, chemical precipitation, and diagenesis. Relationships between sedimentary processes, depositional environments, and the evolution of sedimentary successions.

c) The Metamorphic Process

Metamorphic recrystallization and the principal factors controlling metamorphism. Thermodynamic conditions, stability limits, and the role of pressure, temperature, and fluids in metamorphic processes.

Igneous Rocks

Fundamentals of igneous petrology: nature of melts and magmas, and the chemical and physical properties of silicate systems. Processes of magma generation, evolution, and solidification. Crystallization of silicate melts and application of binary phase diagrams to natural systems.

Magmatic evolution: fractional crystallization.

Influence of the crystallization environment and rates of nucleation and crystal growth on the structures and textures of igneous rocks. Principles and criteria for the classification of igneous rocks.

Magmatic series, variation diagrams, and relationships between magmatism and geodynamic environments.

Sedimentary Rocks

Classification of sedimentary rocks based on depositional processes and textural and compositional characteristics. Paleoenvironmental interpretation of sedimentary successions.

Basic concepts of pedology and soil-forming processes.

Metamorphic Rocks

Factors controlling metamorphism and their role in mineralogical and textural transformations. Controlling factors and kinetic factors.

Types of metamorphism and their crustal and geodynamic settings. Processes of metamorphic recrystallization, metamorphic reactions, kinetics, and reversibility of mineralogical transformations.

Mineral parageneses, relationships between deformation and recrystallization. Structures and textures of metamorphic rocks.

Representation of reactions in pressure–temperature (P–T) space, phase stability, and mineral assemblages. Metamorphic facies, geothermal gradients, facies series, and relationships between metamorphism and geotectonics.

Practical Activities – Igneous Rocks

Methods for rock identification through the analysis of structure, texture, mineralogical composition, and chemical composition.

Study of the principal minerals occurring in igneous rocks: structural and chemical characteristics, macroscopic and microscopic identification, and equilibrium relationships with silicate melts.

Analysis of intrusive, effusive, and subvolcanic rocks; description of igneous structures and textures; and application of the main classification criteria.

Practical Activities – Sedimentary Rocks

Macroscopic identification of the textural, structural, and mineralogical characteristics of sedimentary rocks. Application of the main classification criteria and methods.

Practical Activities – Metamorphic Rocks

Study of metamorphic minerals and their structural and compositional characteristics. Macroscopic and microscopic identification of metamorphic rocks, with analysis of their principal structures and textures.

Two field excursions are planned, devoted to the study of the ophiolitic succession of the Northern Apennines and the Alpine ophiolitic units of the Voltri Group, aimed at the direct observation of their main lithological features.

RECOMMENDED READING/BIBLIOGRAPHY

• Klein & Philpotts – Earth Materials: Introduction to Mineralogy and Petrology. Zanichelli Publishing.
• Morbidelli L. – Rocks and Their Constituents. Bardi Publishing.
• Winter J.D. – An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.

Copies of the PowerPoint presentations used during the lectures will be made available for download on AulaWeb.

TEACHERS AND EXAM BOARD

Exam Board

LAURA GAGGERO (President)

ROBERTO CABELLA

CRISTINA CARBONE (President Substitute)

PIETRO MARESCOTTI (President Substitute)

LESSONS

LESSONS START

From March 1, 2021. Consult the site of the study course for updates.

Class schedule

The timetable for this course is available here: Portale EasyAcademy

EXAMS

EXAM DESCRIPTION

The attending student may take the exam through three written tests and three rock identification assessments during the semester. At the end of the lectures, the final oral interview to assign the grade is based on a summary of any deficiencies found and possible further discussions. The final grade is based on the three written tests, but it is not necessarily their arithmetic average.

Alternatively, the student may register for the official exam sessions held throughout the year. The exam consists of:
i) classification of a rock sample provided during the exam,
ii) three questions on igneous, sedimentary, and metamorphic processes, and
iii) one question related to fieldwork exercises.

ASSESSMENT METHODS

The three written tests during the semester are evaluated based on logical consistency, appropriate use of technical-scientific language, and the ability to apply what has been learned in class.

The final oral interview at the end of the course aims to assess whether the student's preparation has become more solid compared to previous weeks, and whether the student has critically addressed and filled any knowledge gaps identified in the written tests.

The traditional exam session evaluates, through questions ranging from simple to complex, the depth and accuracy of the student's knowledge (factual content), the ability to organize this knowledge into a rational framework, the ability to draw on prerequisite knowledge from Inorganic Chemistry and Mineralogy, and the ability to interrelate connected topics.

A passing grade corresponds to the ability to classify a rock (igneous, sedimentary, or metamorphic) using proper nomenclature criteria, providing justification for their application.

FURTHER INFORMATION

Regular attendance is strongly recommended, especially for the field exercises. Students are required to provide suitable clothing for field excursions (hiking boots) and a magnifying lens.

Students with a certified physical disability or specific learning disorder (SLD) registered with the University can find information about available support services on the dedicated webpage: https://unige.it/disabilita-dsa, managed by the Student Inclusion Services for Students with Disabilities and Specific Learning Disorders (SLD). Students who wish to discuss possible accommodations or other circumstances regarding lectures, coursework, and examinations should speak with both the instructor and Professor Cristina Carbone (cristina.carbone@unige.it), the Department’s disability liaison.