COURSE INFORMATION. NAME OF THE SUBJECT: Petrology of igneous and metamorphic rocks TEACHING STAFF

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1 COURSE INFORMATION NAME OF THE SUBJECT: Petrology of igneous and metamorphic rocks Code number: Degree in Geology Academic Year: Foundational/Elective/Compulsory course. 3 rd year Second semester: 4 1/2 hours a week, 2 days a week 6 credits TEACHING STAFF Prof.: Antonio Castro Dorado Department: Geology Office: EX. P3. N2. 01 Phone: dorado@uhu.es Office hours: First Semester: and Second Semester: and PROGRAMME 1. DESCRIPTION Rocks form most of our planet, they form the continents where life was developed on Earth since the last 3000 millions years. The history of the Earth is written in the rocks in such a way that the study of rocks allows us to reconstruct the complex processes involved in mountain building, volcanism, new crust generation, mantle dynamics, etc. Consequently, Petrology of Igneous and Metamorphic Rocks is a fundamental subject for undergraduate students in Geology. Understanding the rocks, their origin, composition, classification, etc. are the essential basis to set a fundamental background for other geological subjects. The distinction between igneous and metamorphic rocks is conceptually clear. However, the recognition of particular rocks as igneous or metamorphic is not always straightforward. Many metamorphic rocks have an ultimate igneous origin and the igneous past can be, and must be, recognized. Consequently, clear and unambiguous definitions of concepts and terms must be provided to students. On the other hand, rocks are complex in terms of mineralogy, structures and field relations. Thus, the application of rigorous criteria for rock classification must be applied. These are being revised periodically by international, UNESCO-rooted, expert committees, the Sub-commission for the Classification of the Igneous Rocks and the Subcommission for the study of Metamorphic rocks; both part of the IUGS (International Union of Geosciences). Many basic principles are common for igneous and metamorphic petrology. However, the methodology of study of natural rocks differs significantly from one group to the other. Thus, the subject is configured in a first block of lessons about the 1

2 fundamental common principles, and particular lessons treating igneous and metamorphic rocks separately. The subject is conceived in a double sense, conceptual and practical. Lessons are accompanied with practical sessions. A large part of the practical sessions will consist of microscopic studies of rocks representing case-studies of classical petrologic problems. 2. PREREQUISITES The study of rocks requires a solid conceptual basis on thermodynamics and reaction kinetics and crystallization processes. Most igneous and metamorphic rocks are essentially formed by a reduced group of silicate minerals, with subordinate phosphates and oxides as accessory minerals. The identification of these minerals is fundamental to study rocks. Furthermore, rocks form part of large-scale complexes such as mountain chains, the ocean floor, volcanic islands, etc. Thus, the geological setting of igneous and metamorphic rocks constitutes the basis of any petrologic study. In summary, students following this subject must have basic knowledge of the following matters: Chemical thermodynamics Mineralogy of silicate minerals Tectonics and General Geology 3. OBJECTIVES/LEARNING OUTCOMES - A general purpose of this subject is to educate students to think and speak in the scientific way of petrologists. To accomplish this general objective, the following partial objectives and outcomes proposed are: 1. To provide students with the basic knowledge on the physico-chemical processes that lead to the generation of varied rock types in the igneous and metamorphic environments. 2. To provide students with the skills to recognize rocks and to identify processes involved in their generation. 3. The acquisition of a petrological language based on concepts and terminologies applied to the study of rocks. 4. To gain new intuition on physical processes related to the generation of igneous and metamorphic rocks 5. To handle petrological data commonly used in petrological modeling of rock and magma generation. 6. To recognize the rocks in their tectonic environments by projecting rock data into large-scale geodynamic processes. 4. TEACHING METHODOLOGY Lectures and practical sessions will be combined in most of the teaching units listed in the next section. Lectures will tend to provoke the active participation of students. To motivate interaction during lectures, the students will be asked to answer critical questions to follow the explanations. Visual projections will be used for illustrative purposes of geological examples, avoiding excessive lettering. The use of classical blackboard is 2

3 considered essential to help during lectures. The students will be supplied with a handout to follow particular parts of lectures. Lectures will be combined with joint seminars in reduced groups and practical sessions. Practical sessions are focused on petrographic examinations with the optical microscope of rocks from classical associations. Because Petrography is included in another subject (Petrografía) in the Huelva graduate catalog for Geology, the programmed sessions in this subject will be focused on particular processes that have been previously introduced in the lectures. A reduce but intensive field work of two or three sessions is also included as a part of the practical sessions. 5. CONTENTS 1. Lectures: Lectures are organized in three thematic blocks and fourteen lessons. The summarized content of these lessons are as follows: Thematic block one: General Principles of Igneous and Metamorphic Petrology L1: Scope of Petrology Rocks as material and abstract substances. Petrology and thermodynamics. Methods in the study of rocks. Geochemical and geophysical connections. L2: The structure of the Earth The mantle: its composition and thermal regime. The continental crust: its structure, age and composition. The oceanic crust. Heat flow and thermal regime of the lithosphere. Thematic block two: Igneous Rocks L3: Magmas and magmatic rocks Physical properties of magmas. Crystallization of magmatic rocks. Nucleation and growth of crystals. Volatile solubility. Viscosity and flow of magma. Magma chambers and eruption of magma. Shape of plutonic bodies. L4: Phase diagrams in igneous petrology Two component systems. Systems with solid solutions. Systems with peritectic reactions. Ideal systems for basalts and rhyolites L5: Basalts and the origin of basaltic magmas Natural occurrence of basalts. The Bowen s concept of differentiation series. The Yoder-Tilley basalt tetrahedron. The source of basalt magmas. Differentiation of basaltic magmas. Liquid lines of descent for basaltic magmas. L6: Andesites and arc magmatism Natural occurrence of andesites and related arc magmas. Magmatic series: the Peacock index. Origin of andesites. Source components in arc settings. L7: Granite batholiths and the origin of the continental crust 3

4 Rock associations in batholiths. Emplacement mechanisms of plutons and batholiths. Cordilleran and intra-plate batholiths. Granite types. Crustal recycling and granite magma generation. L8: Archaean and Proterozoic igneous rocks. Igneous rocks of the Archaean cratons. TTG complexes and the origin of protocontinents. Proterozoic igneous rocks: massif-type anorthosites and related rocks. Thematic block three: Metamorphic Rocks L9: Metamorphism and metamorphic rocks General principles and definitions. The limits of metamorphism. Metamorphic grade and metamorphic facies. L10: Metamorphic mineral assemblages Equilibrium and compatibility diagrams. Petrogenetic grids. L11: Compositional series Pelites and greywackes. Metabasites and calc-silicate rocks. Metamorphism of ultramafic rocks. L12: Rocks derived from ultrametamorphism and anatexis in the crust Migmatites. Metamorphic reactions leading to melt generation. Congruent and incongruent melting. Peritectic mineral phases and restites. L13: Microstructures of metamorphic rocks Porphyroblast matrix relations and tectonic implications. Intra-crystalline deformation and flow. Deformation mechanisms. Development of foliations in metamorphic rocks. Mylonites and cataclasites. L14: Geothermometry and geobarometry General principles. Solid solutions. Solvus thermometry. Pseudosections. 2. Practical sessions 2.1 Petrological modeling (sessions in reduced groups) - The use of classification diagrams and series characterization in igneous rocks - The use of thermodynamic modeling using the software MELTS - Geochemical modeling of igneous processes by using major and trace elements - Identification of magmatic series. Geochemical discriminant diagrams - Algebraic handling of the compositional space in metamorphic systems - Making compatibility diagrams and identification of equilibrium assemblages 2.2 Microscopic and textural analyses: - Examination of igneous textures and textural modifications in igneous rocks - Examination of textures and rock types resulting of crystallization/differentiation processes - Identification of equilibrium and disequilibrium textures in metamorphic rocks by application of interfacial free-energy principles and dihedral angles. - Porphyroblast-matrix relations and identification of tectonic processes by means of textural analysis 4

5 6. BIBLIOGRAPHY Bucher, K., Grapes, R., 2011, Petrogenesis of Metamorphic Rocks, Springer-Verlag Berlin Heidelberg Castro Dorado, A Petrografía de Rocas Ígneas y Metamórficas. Paraninfo. Madrid. MacKenzie, W.S., Guilford, C., Yardley, B.W.D., 1990, Atlas of metamorphic rocks and their textures. Longman. Maaløe S Principles of Igneous Petrology. Springer-Verlag. Berlin. Philpotts, A.R., Ague, J.J Principles of Igneous and Metamorphic Rocks. Cambridge University Press. Spear, F.S., 1993, Metamorphic phase equilibria and pressure-temperature-time paths. Min. Soc. Am. Monographs. Winter, J., 2001, An Introduction to igneous and metamorphic petrology.prentice-hall. Yardley, B.W.D., 1989, An introduction to metamorphic petrology. Longman. 7. ASSESSMENT Assessment will be based on the following parts: 1. Written exam on fundamental concepts of igneous and metamorphic petrology. 2. Petrographic study of selected rocks in thin sections 3. Continuous assessment according to participation in seminars (reduced groups) and practical sessions The relative charges of these parts in the final assessment are: 1: 50%; 2: 20%; 3: 30% Antonio Castro Professor of Petrology and Geochemistry 5