GEOL30240 Igneous Petrology

Academic Year 2023/2024

The module begins with an introduction to magma sources and the variability of igneous rocks compositions. This is followed by a discussion of the processes involved in generating and modifying magmas, including partial melting, fractional crystallization, assimilation, AFC, mixing and mingling. Techniques used for chemical and isotopic analysis are introduced and the utility of trace elements and radiogenic isotopes in igneous petrology is explained. Magma sources and petrogenetic processes are then discussed in a plate tectonic context. Practical classes amplify the concepts raised in the lectures using graphical plotting and calculations and use thin section petrography to make links between texture and magmatic processes, especially crystallization.

Lectures and online material in the second part of the module explore the petrogenesis of igneous rocks in the framework of plate tectonics, using understanding of magmatic processes, geochemical and isotopic data covered in the first part of the module. It covers the formation of magmas and igneous rocks at mid-ocean ridges, destructive margins, oceanic intraplate settings and at continental rifts. The classification, magmagenesis and emplacement of granites are discussed. Practicals, including thin section petrography, phase diagram interpretation and radiogenic isotope plotting are used to illustrate some of the variety of igneous rocks in these different plate tectonic settings and as evidence demonstrating the generation, evolution and crystallization of magmas.

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Curricular information is subject to change

Learning Outcomes:

On completion of this module students should be able to:
1) Explain how igneous rocks can be classified.
2) Describe the range of processes that lead to the formation of igneous rocks.
3) Be able to identify all of the common rock-forming minerals and some accessory phases in thin sections ofigneous rocks
4) Explain how geochemical and radiogenic isotope data are acquired and their uses in constraining the sources, evolution and crystallization of magmas.
5) Interpret igneous rock textures and mineral assemblages in thin sections and relate thin section observations to inferences drawn from phase diagrams.
6) Critically evaluate the evidence for the petrogenesis of igneous rocks in a variety of plate tectonic settings.

Indicative Module Content:

Indicative module content.

Lecture 1: The composition of Earth’s mantle and crust
Lecture 2: Classification and nomenclature of igneous rocks
Practical 1: Petrography of selected plutonic rocks (diorite & syenite)

Lecture 3: Partial melting and recap of solidus and liquidus curves, basic phase diagram revision
Lecture 4: Fractional crystallisation – minerals, chemical effects, cumulates; immiscibility
Practical 2: Intrusive rock textures

Lecture 5: Igneous textures and their interpretation. Links to phase diagrams
Lecture 6: Geochemical analysis of rocks and data interpretation
Practical 3:Geochemistry practical

Lecture 7: Rb-Sr, Sm-Nd, Ar-Ar isotope systems and their use as tracers
Lecture 8: Magma chamber processes and layered intrusions
Practical 4: Skaergaard petrography

Lecture 9: Assimilation, AFC, MASH, magma mixing and mingling
Lecture 10: Mantle melting processes in plate tectonic context
Practical 5: Volcanic rock textures

Mid-term Exam (45 minute practical + 75 minute theory)

Lecture 11: Mid-ocean ridge magmatism - 1
Online (Brightspace) exercise: Mid-ocean ridge magmatism - 2
Practical 6: Radiogenic isotope ratios in oceanic basalts: probing the mantle

Lecture 13: Island arc magmatism - 1
Online (Brightspace) exercise: Island arc magmatism - 2
Practical 7: Calc-alkaline volcanics of Mexico: petrography and petrology

Lecture 15: Continental destructive margin magmatism - 1; origin and classification of granites
Online (Brightspace) exercise: Continental destructive margin magmatism - 2
Practical 8: Pan-African granites of Dur al Gussa, Libya: petrography and petrology

Lecture 17: Oceanic intraplate and LIP magmatism - 1
Online (Brightspace) exercise: Oceanic intraplate and LIP magmatism - 2
Practical 9. Tahiti ocean island basalt (OIB) igneous activity

Lecture 19: Continental rift alkaline magmatism
Online (Brightspace) exercise: Carbonatites and their relationship to alkaline magmatism
Practical 10: Petrography of Si-undersaturated continental alkaline rocks

End of Semester 45 minute practical + 75 minute theory exam

Student Effort Hours: 
Student Effort Type Hours




Specified Learning Activities


Autonomous Student Learning




Approaches to Teaching and Learning:
A blended learning approach is used. The module consists of 15 in-person lectures. In addition there are 5 online (Brightspace) student-directed learning exercises and ten 2-hour hands-on practical sessions. The practicals are designed to reinforce and develop material presented during the lectures and online exercises are are an essential part of this skills-based course. 
Requirements, Exclusions and Recommendations

Not applicable to this module.

Module Requisites and Incompatibles
GEOL20120 - Investigating Minerals, GEOL20250 - Crystals to Sedimentary Rocks

Assessment Strategy  
Description Timing Open Book Exam Component Scale Must Pass Component % of Final Grade In Module Component Repeat Offered
Continuous Assessment: Assessment of practical notebook (normally weekly) Throughout the Trimester n/a Standard conversion grade scale 40% No


Examination: 2-hour exam on theory & practical work of second half of course Unspecified No Standard conversion grade scale 40% No


Examination: 2 hour exam on theory & practical work of first half of course Week 7 No Standard conversion grade scale 40% No



Carry forward of passed components
Resit In Terminal Exam
Spring Yes - 2 Hour
Please see Student Jargon Buster for more information about remediation types and timing. 
Feedback Strategy/Strategies

• Feedback individually to students, on an activity or draft prior to summative assessment
• Group/class feedback, post-assessment

How will my Feedback be Delivered?

Feedback to students, both individually and as a group weekly via comments on work submitted in lab books. Feedback to group and individually if requested following mid-term exam.

Name Role
Ms Hilde Koch Lecturer / Co-Lecturer