GEOL30110 Metamorphic Petrology

Academic Year 2022/2023

The first part of the module outlines the field appearance and tectonic settings of metamorphic rocks. It deals with the development of metamorphic textures and the mechanisms by which minerals crystallise in the solid state in response to strain and changing pressure and temperature conditions. It covers the mineral assemblages that develop in metamorphosed basic igneous rocks (metabasites), mudstones and shales (pelites) and limestones (calc-silicates) and the methods used to study them in the field and in the laboratory. Laboratory techniques include petrological (optical) microscopy, scanning electron microscopy, electron probe microanalysis, radiogenic isotopic dating and the use and interpretation of chemographic and pressure-temperature phase diagrams. The second part of the module explains how PT conditions are quantified, how isotopic ages are interpreted (crystallization versus cooling) in different tectonic settings, e.g. the Barrovian, Buchan and high pressure (blueschist) styles of regional metamorphism, high temperature (granulite-facies) terrains and the metamorphism of ultrabasic mantle rocks, e.g. in rift zones.

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Curricular information is subject to change

Learning Outcomes:

1) Appreciate the role that metamorphic rocks play in recording Earth's memory of past plate tectonic events. 2) Identify and interpret mineral assemblages and textures in metamorphic rocks. 3) Interpret a variety of chemographic and pressure-temperature phase diagrams. 4) Construct a phase diagram from thermodynamic data and analyse it using Schreinemakers' method. 5) Deduce aspects of the tectonic history from (a) field and petrographic observations, (b), pressure and temperatures excursions inferred from chemical zoning in metamorphic minerals, (c) interpretation of mineral isotopic ages.

Indicative Module Content:

Lectures and practical topics:
Introduction to metamorphic rocks and their role as the memory bank for Earth history and crustal evolution.
Techniques used to investigate metamorphic rocks: petrography (mineral identification and textural analysis (linking mineralogy to deformation); Electron probe microanalysis (in situ chemical analysis of minerals); chemography (diagrams that use chemical compositional information to investigate mineral assemblages); thermobarometry (determining pressure and temperature from mineral equilibria); isotopic dating (introduction to thermochronology).
Classification of metamorphism: regional and contact metamorphism; metamorphic grade; metamorphic facies; metamorphic zones and isograds; prograde and retrograde metamorphism; medium pressur.
Materials (rock compositions and mineralogy): pelite (metamorphosed shale/ mudstone); metabasite (metamorphosed basic igneous rocks); carbonate and calc-silicate (metamorphosed limestones); metaperidotite (metamorphosed ultrabasic rocks); metamorphic fluids (water, carbon dioxide; material transport and ore deposits; gas exchange between lithosphere-atmosphere-hydrosphere); mineral reactions and recrystallization mechanisms related to strain.
Tectonic settings of metamorphism: variations in heat, burial and exhumation (why many metamorphic rocks have been deep and hot but some have been hot near the surface and others have been very deep and yet remained cool); baric types, i.e. low pressure (linked to arc magmatism), medium pressure (linked to plate collision) and high pressure (linked to subduction) metamorphism.
Practical classes will provide experience in investigating the mineralogy and textures of pelites and metabasites illustrating a range of metamorphic PT conditions and textural features from many classic locations.
Projects (case studies) will investigate: (1) contact metamorphism around the Leinster and Skiddaw granites; (2) PT conditions and tectonic inferences from zoned minerals in pelitic rocks from the Grampian orogen; (3) extremes of metamorphism (eclogites and granulites, e.g. from the Slishwood Division and migmatites - when rocks start to melt); (4) deep burial but relatively cool metamorphism associated with subduction zones (blueschists from Achill and Isle de Groix and their preservation/ exhumation).

Student Effort Hours: 
Student Effort Type Hours
Lectures

20

Practical

22

Autonomous Student Learning

58

Total

100

Approaches to Teaching and Learning:
Lectures, practicals related to lecture content, short practical projects and independent reading of text books and research articles. 
Requirements, Exclusions and Recommendations
Learning Recommendations:

GEOL30240 Igneous Petrology


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


 
Assessment Strategy  
Description Timing Open Book Exam Component Scale Must Pass Component % of Final Grade
Continuous Assessment: Assessments of practical work Varies over the Trimester n/a Standard conversion grade scale 40% No

50

Examination: 2-hour exam covering entire course Week 12 No Standard conversion grade scale 40% No

50


Carry forward of passed components
Yes
 
Resit In Terminal Exam
Autumn 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
• Feedback individually to students, post-assessment
• Group/class feedback, post-assessment

How will my Feedback be Delivered?

Weekly feedback on content of practical books

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