GEOS3101/3801 Earth’s Structure and Evolution: unit outlineSemester 1, 2013 6 credit points

Aims: The Earth’s crust and upper mantle, or lithosphere, are a consequence of tectonic and geodynamic pro-cesses operating since Earth’s formation. This unit focuses on information and techniques that enable an un-derstanding of these processes. The main topics presented in this unit include: the formation and evolution of oceanic and continental lithosphere; struc¬tural deformation, magmatism and metamorphism at plate bound-aries; the mesoscopic and microscopic analysis of igneous and metamorphic rocks; mechanisms of heat and mass transfer, and the mechanical behavior (i.e. rheology) of Earth materials. Practical classes are designed to enable students to be competently and independently identify the common crystalline rocks in hand-spec-imen; to gather and interpret the structural field data which enables the determi¬nation of the structural style and deformational history presented in particular tectonic settings, and to understand and interpret petrologi-cal and structural data in terms of thermal and mechanical processes. The concepts and content presented in this unit are essential knowl¬edge for geologists and geophysicists and provide a conceptual framework for their professional practice. There will be a three-day excursion to the South Coast of NSW in the first few weeks of semester to examine relevant themes in a field setting. Students wishing to specialize in the field and become professional geologists will normally need to expand upon the knowledge gained from this unit and either complete an honours project or progress to postgraduate coursework in this field.

Unit Outcomes After completing Geos3101/3801, you are expected to be able to: • identify common rock forming minerals in hand specimen and thin sections; • interpret common mineral textures and rocks fabrics, including finite strain and kinematic indicators; • understand the tectonic, metamorphic and geochemical processes involved in key geodynamic settings, their products and be aware of assumptions underlying their interpretation; • calculate the continental geotherm from observation of surface heat flow and rock content in heat produc-ing radiogenic elements;• understand how lithospheric deformation affects the temperature and pressure evolution of metamorphic rocks; and• when presented with a geological problem, observe and interpret the key data and relationships and pro-vide a satisfactory explanation or interpretation.

Lectures will be delivered at 10 am on Monday in Madsen room 336. Students must attend all lectures to derive benefit from this unit of study. Most lectures will have assigned reading, to be completed in preparation, and some will require group presentations. To maximize learning outcomes and promote a dynamic and collabor-ative learning environment, students are requested to read the lecture material prior to attending the lecture.

Practical classes will be delivered between 2 and 4 pm on Monday or Tuesday in Madsen room 336. The pclass-es will be delivered between 2 and 4 pm on Monday or Tuesday in Madsen room 336. The practical exercises are oriented toward solving problems relevant to the unit objectives and all exercises should be completed. The use of a laptop in the classroom is encouraged. Although simple tools such as Excel and Livemath (no programming required) are sufficient, students are invited to use during the practicals their knowledge of Matlab or Mathematica, or their open source equivalents: Octave, Freemat or SciLab. Lecture notes and supporting material will be available on-line through Blackboard.

Assessment: 40% two hour exam covering theoretical concepts mostly addressed in lectures 30% practical test (week 8; 15%) and presentations (15%) 15% South Coast Field excursion: Friday March 22 - Monday March 25 15% student presentation (week 13) Portions of the unit will be weighted by contact time proportion.

Presentations: Student pairs will be assigned one or two topical research papers on a theme relevant to the unit. Together you will prepare a 4 minute computer video presentation on that topic for delivery during week 13, and a typed 1-2 page synopsis of the topic that should include diagrams. Please attach to the synopsis a signed statement indicating the contribution made by each person. Topics will be assigned by week 5 to give you time to prepare the material; you are encouraged to consult the teaching staff between weeks 5 and 12 with respect to preparation of the talk and synopsis. Your talk should explain the significance of the topic at an introductory level that could be understood by, for example, an interested first year student, and cover sufficient detail to engage your peers (i.e. fellow third year students). It may be a video of yourself delivering the presentation, or mix diagrams and/or animations with such material - its nature is flexible. The material will be placed on a server and made available for comment from an audience outside the University.

Teaching Staff: Geoffrey Clarke geoffrey.clarke@sydney.edu.au

Patrice Rey patrice.rey@sydney.edu.au unit coordinator Jonathan Aitchison

GEOS3101/3801 Earth’s Structure and Evolution

Timetable Lecture title Practical title

Clarke: Earth’s mineralogical evolutionW1 Introduction; asymmetry in petrology Metapelitic rocks and the PT spectrumW2 Petrofabrics and parents Timing mineral growth W3 The subduction factory Subduction metamorphismW4 South Coast excursion South Coast excursion EasterW5 Equilibria and equilibration Petrography and field relationshipsW6 The extremes of metamorphism Trial practical test and reviewW7 Petrology in field work Corona Reaction Textures W8 Practical test

Rey: Earth’s geodynamics and evolution: Tectonic and Geodynamic approachesW9 Heat generation and transfer Continental GeothermW10 Tectonic forces and gravitational forces Isostasy and Earth’s surface elevationW11 The Notion of Rheology Map analysis and cross-sectionW12 The Deformation of the Earth’s lithosphere Interpretation of rock fabrics

W13 Student Presentations Student Presentations

This unit focuses on information and techniques that enable an understanding of how oceanic and continental lithosphere form and evolve through tectonic and geodynamic processes. The unit is divided into petrology (weeks 1–8) and tectonics (weeks 9–13), with a component of fieldwork (week 3) and a group 4 minute video presentation (week 13). Petrology is a core subject in Geosciences, and relates closely to mineralogy, geochem-istry, geo¬physics, tectonics, economic geology and planetary sciences. It is thus a required component of the undergraduate geology cur¬riculum. There are three components to petrology: (i) observation and analysis; (ii) experimental; and (iii) theoretical. Its fundamen¬tal principles are embedded in the disciplines of physical chem-istry, mechanics and transport processes, and material sciences. Geological information comes from the mineralogy, fabric, physical properties and geochemical characteris-tics of rocks. Rock fabric, mineralogy, geochemistry and physical properties evolve in response to changes in stress, pressure, temperature, fluid abundance and composition. These parameters are, in turn, driven by geodynamic and tectonic processes, including subduction, seafloor spreading, continental collision and plate aggregation. In this unit, you will build on material covered in junior and intermediate years to learn fundamental principles of both qualitative and quantitative approaches in petrology and structural geology, to be able to solve geological problems on diverse scales. Using a combination of conceptual and problem-based learning, you will examine the structural, metamorphic and magmatic evolution of the oceanic and continental lithosphere at active plate margins. The structural, metamorphic and magmatic evolution of the lithosphere mostly unfolds over time scales several orders of magnitude longer than our lives, limiting our ability to directly observe many key processes. Thus, we study it by analyzing the end products (what we can see: structural fabrics and regional finite strain, mineral-ogical assemblages, chemical and isotopic composition etc) from which lithospheric tectonic evolution and changes in the intensive physical variables can be unraveled. In the first eight weeks of Geos3101/3801, Geoff will lead practical classes where you will perform mesoscopic and microscopic analysis of igneous and metamorphic rocks and become competent in the identification of the common crystalline rocks through solving mesoscopic and microscopic problems that reflect macroscopic processes. Related lectures will address the fundamental parameters of how and why mineral equilibria change, and, as we can only rarely observe the changes, methods that let us anal¬yse and track such processes. Having a sound understanding of rocks at the mesoscopic and microscopic scale, you will jump to the macroscopic scale in weeks 9 to 12 to learn, in Patrice’s classes, the physical principles and processes driving petrologic changes and to understand the interplay between plate boundary forces, internal forces, continental geotherm, and crustal flow. In his lectures, Patrice will emphasize the important role of heat generation and transfer in the definition of the continental geotherm, and the origin of plate boundary forces and that of volume forces. Finally you will learn about the rheology of the mantle, the continental lithosphere and the oceanic litho¬sphere. At completion of this part of the course you will have a sound understanding of the interdependence between tectonic processes, heat transfer and metamorphic evolution. Throughout the semester you will also complete independent research by preparing a 4 minute video and a 2-page synopsis on an assigned topic. To complete this task, you will need to access the University library and download appropriate material relevant to the course of weeks 1 to 12. Presentations will be delivered in week 13.

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cula

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te a

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ng o

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le to

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rate

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w a

mat

hem

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al

reci

pe to

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ve m

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l pro

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s

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lain

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e to

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ct th

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eolo

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profi

le fo

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tinen

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ic li

thos

pher

es A

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be

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to e

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ate

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r res

pect

ive

inte

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ed s

treng

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expl

ain

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conc

ept o

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tle-d

uctil

e tra

nsiti

on, A

ND

to b

e ab

le to

exp

lain

how

this

tran

sitio

n ch

ange

s w

ith

tem

pera

ture

and

stra

in ra

te; a

nd i

ndep

ende

ntly

est

ab-

lish

a m

athe

mat

ical

sol

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n to

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eolo

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blem

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As

abov

e

Stu

dent

s M

US

T at

tain

a p

ass

or h

ighe

r gra

de in

ALL

sub

ject

are

as.

Not

es1

C

omm

on ig

neou

s ro

cks:

thos

e de

fined

in th

e IU

GS

cla

ssifi

catio

n of

igne

ous

rock

s (L

e B

as &

Stre

ckei

sen,

Jou

rnal

of t

he G

eolo

gica

l Soc

iety

of L

ondo

n, 1

48, 8

25–8

33, 1

991)

. C

omm

on m

etam

orph

ic ro

cks:

refe

r to

glos

sary

from

Ver

non

& C

lark

e (2

008)

giv

en o

n B

lack

boar

d si

te.

Com

mon

min

eral

s: th

ose

form

ing

com

mon

igne

ous

and

and

met

amor

phic

rock

s, a

s ex

amin

ed in

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Textbooks for background reading

Ben van der Pluijm and Stephen Marshak, 2004. Earth Structure An Introduction to Structural Geology and Tectonics. WW Norton & Company. Second Edition.

Bucher, K. & Frey, M., 1994. Petrogenesis of Metamorphic Rocks. Springer. Comprehensive rewrite of Winkler’s dated but valued text.

Deer, Howie & Zussman,1992. An Introduction to the Rock Forming Minerals, 2nd edition. Longman. Standard reference for mineralogy and mineral chemistry.

Dickin, Radiogenic Isotope Geology. Cambridge. Recent text for isotopic petrology and geochronology.

Kearey & Vine, 1990. Global Tectonics. Blackwell. Excellent summaries of geodynamics, though a rewrite will be released in 2008 (Kearey, Vine & Klepeis).

Marshak, S., 2008. Earth, Portrait of a Planet, 3rd edition. Norton & Co., New York. This is the recommended first year text and covers many basic issues very well.

Rollinson, H.1993. Using geochemical data. Longman. Great summaries of isotopic petrology, geochemistry and the uses of trace element data in petrology.

Spear, F.S., 1993. Metamorphic Phase Equilibria and P-T-t paths. Mineralogical Society of America, Monagraph. Detail on what the title suggests, but this will take some time for you to get in.

Vernon, R.H., 2004. A practical guide to rock microstructure. Cambridge.Vernon, R.H. & Clarke, G.L., 2008. Principles of Metamorphic Petrology. Cambridge.

You received a preliminary copy of Chapter 1 last year, attached is Chapter 2.Wilson, M. 1989. Igneous Petrogenesis, A Global Tectonic Approach. Chapan & Hall

Chapters 1-3 provide an excellent petrologic background.Winter, 2001. Igneous and metamorphic Petrology.

Good coverage of some fundamental issues.Yardley, B.W.D., 1989. An Introduction to Metamorphic Petrology. Longman.

An excellent and compact reference.

Reading for Lectures

Week 2 Petrofabrics and parents Comment

Group 1 Vernon (2004), Chapter 3.1–3.7. Microstructure of igneous rocks Group 5Group 2 Vernon (2004), Chapter 4.1–4.9 Microstructure of metamorphic rocks Group 6Group 3 Vernon & Clarke (2008), Chapter 3.1–3.5; Time of mineral growth relative to structural fabrics Group 7Group 4 Vernon & Clarke (2208), Chapter 7. Parent Rocks Group 8

Week 3 The subduction factory

Group 5 Gill, Jim. “What is ‘Typical calc - alkaline andesite?’” In Orogenic Andesites and Plate Tectonics. Group 1 New York, NY: Springer-Verlag, 1981, chapter 1, pp. 1-12. ISBN: 9780387106663.

Group 6 Tatsumi & Kogiso (2003). The subduction factory: its role in the evolution of the Earth’s crust and mantle. Group 2 Geological Society, London, Special Publications 2003, v. 219, p. 55-80. doi: 10.1144/GSL.SP.2003.219.01.03

Group 7 Subduction Factory I Hacker et al. (2003). Journal of Geophysical Research, 108. Group 3Group 8 Why is lawsonite rare? Group 4

Whitney & Davis (2006) Geology June, 2006 v. 34, no. 6, p. 473-476, doi: 10.1130/ G22259.1 Clarke et al. Journal of Metamorphic Geology Volume 24, Issue 8, pages 715–725, 2006, DOI: 10.1111/j.1525-1314.2006.00664.x

From Ben van der Pluijm and Stephen Marshak, 2004. Earth Structure An Introduction to Structural Geology and Tectonics. WW Norton & Company. Second Edition. Week 9: Chapter 1: Overview Week 10: Chapter 3: Force and Stress Week 11: Chapter 5: Rheology Week 12: Chapter 14: Whole Earth Structure and Plate Tectonics

Lecture Presentations

Groups nominated will prepare a 20 minute presentation covering the key elements of the assigned topic. You are expected to cover the main issues in the topic, including overall context and relevance to the theme of the unit. It may be that you need to com-plete additional reading to provide context. Your presentation should be prepared for the benefit of your peers (not the lecturers), and should engage them.

Groups nominated to comment are expected to review and discuss key issues presented on the assigned topic, and seek the clari-fication of ambiguous or possibly less well explained issues. Your comment is expected to be supportive and exploratory, and will additionally require that you prepare a page for handout to the class summarising key points.

Groups will be marked on both presentation and comment.

Criteria for the assessment of presentations

Goals in getting you to give a talk include giving you practice at the exercise and getting you to think about and discuss themes relevant to the unit of study outcomes. Due to the time frames in which geology operates, interpretations of many processes are ambiguous and you should learn to critically appraise theories. So be prepared to ask questions! Some topics are easier than others, and this will be considered in the assessment. However, whenever you give a presentation, you can consider the following criteria, not all of which may apply to a given exercise:

A: General presentation (30%) 1 INTRODUCTION - was it effective in laying the groundwork for body of talk 5 %2 DELIVERY - smooth and well paced 10 %3 GRAMMAR and word choice 5 %4 TIMING-finish in time allowed 5 %5 SUMMARY / conclusion - organized and reinforced main points 5 % B: Visual aids (20%)1 Could you read / COMPREHEND them? 10 %2 SEQUENCE - was it appropriate? 5 %3 EFFECTIVENESS - in supporting conclusions 5 % C: Content and organization (40%)1 LOGIC- logical and smooth progression from problem through study to result 10 %2 SIGNIFICANCE - new and useful contribution? 10 %3 RELEVANCE- of presented material to the task 10 %4 CONCLUSIONS - well-supported and documented 10 % D: Audience response (10%)1 QUESTIONS - several, indicating audience interest 5 %2 REPLIES - well handled 5 %