Undergraduate Course: Advances in Metamorphism (EASC10073)
|School||School of Geosciences
||College||College of Science and Engineering
|Credit level (Normal year taken)||SCQF Level 10 (Year 4 Undergraduate)
||Availability||Not available to visiting students
|Summary||The study of metamorphic rocks and their implications for understanding mountain belts and the tectonic evolution of the Earth has undergone a radical transformation over the past decade - with extreme metamorphism at ultrahigh T and P being now recognised as central to any models for the Earth, vastly improved thermodynamic methods allowing better P-T estimation, and advances in mineral dating enabling much better time constraints to be placed on processes.
This course will cover these advances. Formal lectures, tutorials and practical sessions will be complemented by assignments and exercises undertaken by the students.
The following topic areas will be covered:
- The Phase Rule and its applications
- Schrienemakers analysis and chemographic principles
- Divariant equilibria and P-X, T-X and pseudosection analysis
- Applications of phase diagrams to UHT rocks
- Ti-Zr thermometry for UHT rocks
- Zircon isotopic and Monazite chemical dating and P-T-time records
Practical (laboratory examination of material, graphical analysis and computer-based calculations of equilibria) will accompany some of these topics.
The option will utilise a basic knowledge of mineralogy, chemical equilibria, geochemistry and metamorphic petrology drawn from G3 course work.
The syllabus is constructed from the following topic areas. Not all of these may be covered in any one year, depending on student numbers and experience (e.g. MEarthSci / honours level).
- The Phase Rule, Chemographics and Metamorphic Phase Diagrams:from AFM to Schreinemakers┐ analysis, and to calculated P-T pseudosections and further contoured phase diagrams.
- Advances in thermometry of UHT rocks using Ti in zircon and quartz, and Zr in rutile. Results, implications, caveats.
- Reaction textures: Principles of interpretation and caveats, the roles of fluids, formation mechanisms, examples. P-T grid, Pseudosection and other forms of analysis.
- Advances in accessory mineral age dating: Zircon behaviour and linkage to P-T via reactions and chemistry; Monazite and its behaviour; P-T-time paths and implications for rates and settings.
Entry Requirements (not applicable to Visiting Students)
||Other requirements|| None
|Additional Costs|| none
Course Delivery Information
|Academic year 2016/17, Not available to visiting students (SS1)
|Learning and Teaching activities (Further Info)
Lecture Hours 15,
Supervised Practical/Workshop/Studio Hours 15,
Programme Level Learning and Teaching Hours 2,
Directed Learning and Independent Learning Hours
|Assessment (Further Info)
|Additional Information (Assessment)
||Written Exam: 0%, Course Work: 100%, Practical Exam: 0%.
20% laboratory-based exercise, examining and describing / interpreting a thin section of a classic UHT rock (see below for details).
80% Essay: Presentation and critique of metamorphic work on a selected UHT metamorphic area (Case Study Project: see below for details).
Laboratory-based exercise: Petrogenesis of a UHT rock (Report, 20%)
The student is provided with a thin section of a rock from a classic UHT region or area. The area may be the same as that which he or she will work on in Assessment 2, but is more likely to be from one of the COs pet UHT areas (Mather Paragneiss, Napier Complex, or South Harris).
The student examines the thin section in depth, and then writes a short report on it, with the following aspects incorporated into that report:
Part 1: Petrography, including mineralogy, mineral textures and reaction relationships. This should incorporate colour microphotographs of the key features (digital images taken on the microscope in the Optical Room), and use these creatively but carefully to deduce, where appropriate, and illustrate key reactions.
Part 2: A P-T analysis based on the petrography of the rock, using simple (MAS, FMAS) and more complex (KMFASH) grids (and even pseudosections) to define qualitative to pseudo-quantitative P-T paths.
Petrographic Description and Analysis Report Length: Maximum 4 sides, including photomicrographs, figures, tables and references. Font size (for text) no less than 11 point Times Roman or 10 point Arial. Word Limit for the main text (i.e. excluding figure captions and reference list) is 1000 words.
Case Study Project on a UHT Metamorphic Area (Essay, 80%)
This project forms the principal assessment for the metamorphic option. Students are provided with lead pdf's on Case Study areas, one Case Study area for each student. The case study areas are all examples of UHT (or near-UHT) granulite localities or terrains that have been subjected to analysis using petrographic, phase equilibria and geothermobarometric approaches, and each also has age information. In each case previous workers have established or proposed P-T conditions and P-T paths, and also attempted to produce P-T-t paths.
The student task is to produce a report on their case study. This report should utilise the work we have done on how to use and interpret phase diagrams, and other metamorphic data, to develop a critical discussion of the P-T and, where possible, P-T-t paths proposed for your case study. The report should therefore be structured along the following lines, with variations described under details relating to individual Case Study areas:
Part 1: Context - background geology and why understanding the nature of the UHT metamorphism in the case study area is important.
Part 2: Description of the key aspects of the petrography, including mineralogy, mineral textures and reaction relationships. You should, where appropriate in the light of the published photomicrographs, comment on the validity and quality of the petrographic observations and highlight any inconsistencies or cases where features are left 'dangling' without discussion or interpretation by authors.
Part 3: Presentation and then discussion of the P-T information and P-T and/or P-T-time paths, based on your critical review of the presented pseudosections, geothermobarometry, age dating and so on.
The essay should illustrate that the student understands the principles (e.g. phase diagrams, geothermobarometry, age dating) and can apply those to clearly describe what is reported about the UHT case study and evaluate, to a reasonable extent and given the absence of his/her own data, the robustness / quality of the interpretations made in the literature. Ultimately the one-line question to address is 'How well do we understand this example, in the light of the evidence?'.
Case Study Essay Length: Maximum 16 sides, including figures, tables and references. Font size (for text) no less than 11 point Times Roman or 10 point Arial. Word Limit for the main text (i.e. excluding figure captions and reference list) is 3000 words.
First Assessed Report (Petrogenesis of a UHT rock): 1200, Thursday 2nd March.
Assessed Project (Case Study): 1200, Tuesday 28th March.
||Feedback is provided through the following avenues:
1. In-class Q&A sessions on the material presented as lectures;
2. Explicit follow-up on formative practical exercises on using the phase rule and constructing phase diagrams (schreinemaker's analysis, P-T-X diagrams, simple pseudosections). Students undertake these exercises in their own time and then the exercises are worked through in real time in the following lecture / practical class before proceeding on to the next topic.
3. Explicit follow-up of short calculation-based exercises (Ti or other thermometry, re-calculation of compositions in molar terms, 'rough' calculations of test equilibria). Students undertake these exercises in their own time and then the exercises are worked through in real time in the following lecture / practical class before proceeding on to the next topic.
4. Discussion of key features of student thin sections, by arrangement, on the petrographic microscope.
5. Written feedback and indicative class (provisional mark) on the first summative assessment (the 20% lab-based petrographic exercise).
|No Exam Information
On completion of this course, the student will be able to:
- An understanding of the graphical and thermodynamic principles and techniques used in the analysis of mineral equilibria in high-grade metamorphism.
- An appreciation of the recent advances in the ways in which the understanding of metamorphism and metamorphic processes have developed through thermodynamic and experimental approaches.
- Enhancement of skills to perform thermodynamic calculations on metamorphic examples to extract P-T information.
- Enhancement of petrographic skills to integrate the calculations and mineral age data with microtextural observations to construct P-T-t records of crustal rocks.
- Development of a detailed knowledge and understanding of a selected UHT area involving the critical appraisal of relevant current literature.
|Orogenesis: the making of mountains (MRW Johnson & SL Harley, CUP, 2012)|
Papers from the following issues of Elements:
Zircon - Tiny but Timely (volume 3, number 1, February 2007)
Thermodynamics of Earth Systems (volume 6, number 5, October 2010)
When the Continental Crust Melts (volume 7, number 4, August 2011)
One Hundred years of Geochronology (volume 9, number 1, February 2013)
Further references specific to selected case studies are provided in the course website at the time of setting of those case studies.
|Graduate Attributes and Skills
||Use of computer programs for calculation of equilibria
Preparation of report on lab investigation
Production of report on a literate exapmle of UHT
|Keywords||EASC10073 metamorphismthermodynamicsphase diagramsaccessory mineralsU-Pb geochronologyP-T pathUHT
|Course organiser||Prof Simon Harley
Tel: (0131 6)50 8547
|Course secretary||Miss Sarah Thomas
Tel: (0131 6)50 8510
© Copyright 2016 The University of Edinburgh - 3 February 2017 3:48 am