99903 - PETROGRAFIA (10 CFU)

Academic Year 2022/2023

Learning outcomes

Students will acquire the ability to describe igneous and metamorphic rocks in the field (outcrop scale) and in the lab (hand samples; petrographic thin sections). With this new knowledge, students will be able to understand the main igneous and metamorphic processes and their geologic significance.

Course contents

Review of rock identification and classification - General review of the most common magmatic, metamorphic, and sedimentary rocks and their forming minerals. Classification criteria. Since this is part a review, students are required to study on their own in the available student facilities.

Igneous rocks - The magma: physical and chemical features. Upwelling and solidification of magmas: intrusive vs. volcanic settings. Origin of mantle magmas. Igneous differentiation: fractional crystallization, gravitative setting and cumulus rocks, assimilation, mixing and mingling of different melts. Bowen's reaction series. Anatectic magmas and origin of granites. Mineralogical and chemical features of igneous rocks. Classification of igneous rocks. Magmatic series and their relation to different geodynamic settings.

Metamorphic rocks - Definition and its drivers: pressure, temperature, deformation and fluids. Meso/microstructures and their classification. How to classify a metamorphic rock. Netamorphic reactions and the record they left into the rocks. Metamorphic grade and facies. Metamorphic facies series. Geotherm and Pressure-Temperature-time paths. Regional metamorphism (subduction, orogenic and sea floor) and contact metamorphism.

Laboratory of optical microscopy for petrographic analysis - Classification, analysis and interpretation of igneous and metamorphic rocks by polarizing optical microscopy.

Field Trip - A single-day excursion with practical exercises of classification of igneous and metamorphic rocks.

Readings/Bibliography

Klein C., Philpotts A. (2018) Mineralogia e Petrografia (1a ed. italiana), Bologna, Zanichelli. Pagine: 544. ISBN: 9788808320605

WINTER, John D. Principles of igneous and metamorphic petrology. Pearson education, 2013.

Philpotts A., & Ague J. (2022). Principles of Igneous and Metamorphic Petrology (3rd ed.). Cambridge: Cambridge University Press. doi:10.1017/9781108631419 (or older editions)

HOWIE, R. A.; ZUSSMAN, Jack; DEER, W. An introduction to the rock-forming minerals. Mineralogical Soc of Great Britain; 2013. third edition (or older)

Teaching methods

Class lectures augmented by

  • Rock sample practicals (review)
  • Optical petrography practicals
  • Field Excursion

As concerns the teaching methods of this course, all students must attend the course on health and safety that consists of the online Modules 1 and 2, and Module 3 in class.

Information about Module 3 attendance and schedule is available on the website of your degree programme.

Assessment methods

Final assessment: practical exam + oral exam.

The practical exam consists in a 2-hr session aimed at describing and classifying igneous and metamorphic rocks thin section using a polarizing optical microscope. Each student will receive two thin sections. At the end of the practical exam, the student must deliver a written report in which he/she highlights the mineralogical and microstructural characteristics of the rocks, as well as their classifications and genetic features.

If the practice test fails, the student will not proceed to the oral interview. If the practical test is successful, the candidate proceeds to the oral exam in order to test their knowledge and level of understanding of the theoretical principles treated during the course. The identification and classification of hand specimens may also be considered during the oral exam.

The final exam aims to test:

  1. skills in the recognition of minerals and structures and classification of rocks at various observation scales
  2. knowledge of the main topics covered in class.

As for point (1), the student must be able to:

  • know and understand the basic criteria and terminology to describe and classify a rock at the different observation scales,
  • apply basic knowledge to the interpretation of the origin and evolution of a rock sample,
  • organize logically and describe the information obtained from the analysis of rock samples,
  • critically evaluate these observations, highlighting the limits and uncertainties this approach

As for point (2), ("knowledge of the main topics covered in class") the main evaluation criteria are:

  • Terminological accuracy and correct use of the specialized lexicon;
  • Ability to use the basic petrographic knowledge during the argumentation;
  • Focusing on the question = don't go off topic
  • Logical sequence in reasoning;
  • Ability to take a critical position regarding one's own arguments and those of others;
  • Creativity to solve interpretation issues.

Teaching tools

  • Video Projectors supporting Power Point presentations
  • Devices for remote teaching
  • Hand-sized samples
  • Thin sections
  • Polarizing Optical Microscopes
  • Mineral and rock collections of the Mineralogical collection Museo Luigi Bombicci 

Office hours

See the website of Alberto Vitale Brovarone

See the website of Roberto Braga

See the website of Veronica Peverelli