Faculdade de Ciências e Tecnologia

Igneous and Metamorphic Petrology

Code

10665

Academic unit

Faculdade de Ciências e Tecnologia

Department

Departamento de Ciências da Terra

Credits

3.0

Teacher in charge

Joaquim António dos Reis Silva Simão

Weekly hours

4

Total hours

62

Teaching language

Português

Objectives

 

The study of igneous and metamorphic rocks I and specimen an in thin section. Comprehension of the geological processes responsible for rock diversity; Chemical and mineral compositions which lead to mineral assemblages during geological processes in different tectonic environment.

Prerequisites

 

Frequency on General Geology and Mineralogy  is advised.

Subject matter

Notion of rock. Petrography and Petrology. Petrogenesis. History and development of petrology. The Geological Cycle and the three basic types of rocks: igneous, metamorphic and sedimentary rocks. Structure and Composition of the earth.

Notion of magma. Plutonic rocks (abyssal); rocks filonianas (hipabissais), volcanic (lava or effusive or extrusive).

Relationship between crystallinity of igneous rocks and their mode and place of training: holocristalinas rocks, hemicristalines and glassy.

Reference to metasomatism and granitization. Rock forming minerals. Essential minerals, and minor accessories.

Mode of deposit of igneous rocks: intrusive and extrusive forms.

Types of volcanism.  Secondary products of volcanic activity (pyroclastic). Phenomena of disjunction.

Textural characteristics (structural) of igneous rocks. It’s relationship with the mode of formation. Granularity of igneous rocks.

The form of the mineral constituents. Habit of crystals. Description of the main textural types (structural) of igneous rocks.

 

Generation and evolution of magmas.

Relationship between the location of the phenomena of volcanism and the mechanisms of construction and destruction of the earth''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''s crust in the general framework of global tectonics

The primary magmas as a probable product of partial melting of mantle rocks. Partial melting. Magmatic differentiation, assimilation and magma mixing. Classic examples of magmatic differentiation.

Factors that may depend on the initial composition of a primary melt. Fractional crystallization. Silicates and Bowen''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''s reaction series. Zoned crystals. Fractional crystallization in the stratiform Bushveld Complex, Skaergaard and Stillwater.

Possibility of some granitic rocks have been formed by magmatic differentiation of basic magma.

Analysis and interpretation of the diagram of Niggli.

Composition of igneous rocks: major elements (trace elements) and minor elements (in trace, trace).

Concept of MODA (modal composition) and NORMA (composition rules). Reference to the classification scheme of igneous rocks produced by Cross, Iddings, Pearson and Washington (CIPW).

Calculation of a NORMA.

Streckeisen classification of igneous rocks. Minerals used in the classification of igneous rocks (Q, A, P, F, M).

Main criteria for classification. Estimates of possible chemical compositions of various types of igneous rocks considering the characteristic limits of variation and trends of the percentages of Al2O3, CaO, FeO and Fe2O3.  HARKER Diagrams. Notion of petrogragenetic province.

Basalts and their evolution. Types of basalts. Classification of Yoder & Tiley.

Systematics of igneous rocks. Ultrabasic rocks, dunites, peridotites, etc. Granular basic rock, gabbros and dolerites of different types. Mineralogy, textures and occurrences.

Rock types originated by differentiation of tholeiitic magmas (andesites, dacites, rhyolites) and alkaline magmas (hawaitos, mugearitos, traquiandesitos, trachytes, alkali rhyolites). Probable depths of formation of different types of basaltic magmas.

Rocks Intermediate Diorites and andesites, dacites and granodiorites. Mineralogy, events and relationship to plate tectonics. Examples. Syenites, trachytes (silica undersaturated and types). Occurrence of mineral deposits associated with them. Anorthosites. Composisional and textural characteristics of anorthosites, origin, occurrence, facts and issues. Mineralization associated.

Acidic rocks, granites and rhyolites. Types and sources of granite: igneous, sedimentary and anorogenic.

Rocks Special pegmatites. Occurrence and paragenesis. Carbonatites. Kimberlites.

 

Portuguese intrusive massives: Sintra, Sines and Monchique, Volcanic Complex of Lisbon, Mafra. Lithologies, modes of occurrence, lithological associations. Relation with the global tectonics.

 

Concept of metamorphism and metamorphic rock. Limits of metamorphism: the importance of fluid pressure and the definition of the limit metamorphism / magmatism; limit diagenesis / metamorphism. Geothermal gradients and different regimes of metamorphism.

 

Metamorphic conditioning factors: temperature, pressure, the fluids and the chemical composition changes; time.

 

Notion of metamorphic grade. Types of metamorphism: impact metamorphism, cataclastic metamorphism, contact metamorphism, hydrothermal metamorphism, metamorphic subsidence; regional metamorphism.

 

The Regional metamorphism and its importance in the overall context of the Earth as a dynamic planet. Position on the conditions of pressure and temperature of each type of PT diagram a metamorphic.

 

Concept of metamorphic facies. Assumptions involved in defining the concept of metamorphic facies. Facies metamorphic rocks and their relative positions in space PT.

 

Solid solutions, chemical reactions and metamorphic facies. Chemical compositions of protoliths as affecting metamorphic parageneses.

 

Isograd. Metamorphic facies series of progressive metamorphism.

 

Regional metamorphism rating based on P / T: low, medium and high P / T.

 

Criteria for the Classification of metamorphic: developing foliation and its relationship with the composition of protolith and the action of directed pressure; granularity and their relationship to the crystallization temperature and the nature of the mineral.

Bibliography

Botelho da Costa, J. (1998) - Estudo e classificação das rochas por exame macroscópico. 9ª edição, Fundação Calouste Gulbenkian.

Cox, K. G.; Bell, J. D.; Pankhurst, R. J (1981) - The Interpretation of Igneous Rocks. London.

Frank Press, Raymond Siever (2003) - Understanding Earth, fourth edition, W. H. Freeman.

Kerr, P. C. (1977)- Optical Mineralogy. Mcgraw-Hill College.

Klein, Cornelis; Hurlbut, Cornelius (1999) - Manual of Mineralogy (after D. DANA). 21th Edition revised. Jonh Wiley and Sons, Inc.

Le Maitre, R.W. (1989) - A classification of Igneous Rocks and glossary of terms. Recommendatios of the International Union of Geological Sciencies Subcommition on the Systematics of Igneous Rocks- Blackwell Scientific Publications.

Mackenzie, W. S.; Guilford, C. (1980) – Atlas of rock forming minerals in thin section. Longman Group Ltd.

Mackenzie, W. S.; Donaldson, C.H.; Guilford, C. (1982) – Atlas of igneous rocks and their textures. Longman Group Ltd.

Manuel Bravo – Textos de apoio da disciplina de Petrologia Ígnea e Metamórfica. DCT/FCT/UNL.

Miyashiro, A. (1994) – Metamorphic Petrology. UCL Press Limited, London, 404 p.

Yardley, B. W. D.; Mackenzie, W. S.; Guilford, C. (1990) – Atlas of metamorphic rocks and their textures. Longman Group Ltd, 120 p.

Wilson, M. (1991). Igneous Petrogenesis. A Global tectonic Approach. Harper Collins Academic. 466p.

Teaching method

 

The course is oriented in theoretical and practical classes and having a strong practical component. Study and petrography of the main types of igneous and metamorphic rocks in hand specimen and thin section under the polarizing microscope. Description of textures and identification of essential and accessories minerals. Use of the Streckeisen and Travis sistems for the classification of igneous rocks.

Evaluation method

4 mini-tests, 2 theoretical (60%) and 2 practical (40%).

Final Exam.

Student frequency is obtained with the presence on two-thirds of the practical classes.

Courses