GEOL333 (Fall 2004) Structural Geology and Orogenesis

Tu Th 11:00 - 12:15. Labs Tu 1:00 - 3:50. Mount Holyoke College

Michelle J. Markley

office: 326 and 329 Clapp Hall ; office phone: 538-2814; email: mmarkley@mtholyoke.edu

office hours: Mondays 11:00 – 1:00

Objectives

This course covers the basic techniques of field geology, structural analysis, and multidisciplinary approaches to mountain building (orogenesis). Lectures concentrate on field techniques, stress, strain, faulting, folding, fabric, rock strength, the relation between rock deformation and metamorphism, isotopic systems and deformation mechanisms. Of seven labs, five are field trips that involve collection of original data. Seven short problem sets emphasize quantitative skills. During the final weeks of the semester, students research the Swiss Alps (Helvetic and Jura Provinces). A final paper and two oral presentations emphasize fluency in the published literature of structural geology. Class participation makes up 10% of the final grade.

Text

G. H. Davis and S. J. Reynolds, 1996, Structural Geology of Rocks and Regions, second edition (Wiley) is available from the Odyssey bookstore.

Problem sets

The purpose of problem sets is to hone your quantitative skills. I will pass out homework assignments on the days specified in the syllabus. In general, the completed assignment will be due a week after you receive it (at the beginning of class). Each homework assignment is worth 2 points--the first for its timely completion and the second for the correct answer. I encourage you to work in groups on these problem sets. They make up 10% of the final grade.

Labs

Labs include two components: (1) making and documenting original observations, and (2) interpreting these observations in the context of class lecture material. Although I expect each of you to make original observations and interpretations, I encourage you to work together to develop strategies and ideas.

Labs are due to me a week after they are introduced to you, and I will return them one week later. Labs are late if I receive them after I have begun grading. Late labs garner no credit, but I will make comments on them as I do on graded labs. An enclosed set of "guidelines" summarizes my expectations for these lab reports. The syllabus contains a sheet called “Lab Write-ups” that will serve as the format for grades. Labs make up 40% of the final grade.

Oral presentations

Each student will make two oral presentations to the class. During each presentation, you will present material from an article on the geology of Swiss Alps. Please practice your presentations at the Speaking Center. The syllabus contains a sheet called “Class Presentations” that will serve as the format for grades on oral presentations. Each oral presentations makes up 10% of the final grade.

Final paper

A short (3 page) paper is due at the end of the semester. This paper is the only final assignment in the class, so use it as an opportunity to review and clarify material from the lectures and labs, or as an opportunity to extend your new knowledge into other disciplines. The final paper makes up 20% of your final grade. This syllabus contains detailed descriptions of possible paper topics and format. I will run lab-time peer review sessions of the first draft of this paper. You must bring two copies of the complete first draft of your paper to the peer review session and turn in the second draft on the date specified in the syllabus.

Optional field trip

Please attend New England Intercollegiate Geological Conference (NEIGC) field trip B-2 with me (see www.salemstate.edu/~lhanson/NEIGC/2004NEIGC.html), on Saturday October 9 (WARNING--this is during mid-semester break).

Books on reserve at the library

G. H. Davis and S. J. Reynolds, 1996, Structural Geology of Rocks and Regions, 2nd edition (Wiley). This is your text. (QE601.D3 1996 Folio)

S. Marshak and G. Mitra, 1988, Basic Methods in Structural Geology (Prentice Hall). This is a standard lab manual for structural geology that has two parts: (1) "Elementary Techniques," with great how-to chapters on stereonets, attitude calculations from field data, and contour map construction; and (2) "Special Topics," with a wide range of mostly excellent chapters on topics such as rock deformation experiments, folds, cross-sections, and strain analysis. (QE601.M365 1988)

E. M. Moores and R. J. Twiss, 1995, Tectonics (W. H. Freeman and Company). This is a good introduction to plate tectonics. (QE601.M65 1995 Folio)

C. W. Passchier and R. J. Trouw, 1996, Microtectonics (Springer-Verlag). This is a beautiful book intended for students at an advanced level. It has great photomicrographs (photos of thin sections of deformed rocks) and contains unusually well written chapters on a range of topics including flow and deformation, deformation mechanisms, small scale structures, and how-to advice on orienting and cutting samples for structural analysis. (QE440.P38 1996)

R. J. Twiss and E. M. Moores, 1992, Structural Geology (W. H. Freeman and Company). This is a solid intro level text for structural geology that goes into more detail on most topics than your text does. (QE601.T894 1992 Folio)

B. van der Pluijm and S. Marshak, 1997: Earth Structure; an Introduction to Structural Geology and Tectonics (WCB/McGraw-Hill). This is another good intro level text. (QE601.V36 1997 Folio)

Educational CD on reserve at the library

H. R. Burger and T. A Harms, An Introduction to Structural Methods v. 1.0 (Tasa Graphical Arts). An educational resource that includes excellent units on the orientations of lines and planes, stereographic projection, and geologic map interpretation. Use it to educate yourself or review material from lecture.

Class schedule

If it's in italics, then bring it in or suffer!

If it's a Chapter in bold, read it in Davis and Reynolds or fall behind!

I. Introduction (Chapter 1; Part III sections A-D & H)

Thursday 9/9: Location and Orientation

PROBLEM SET #1: Strike and Dip

II. Brittle structures (Chapters 3, 5, and 6)

Tuesday 9/14: Stress

LAB #1: Journal of Structural Geology

Thursday 9/16: Mohr Circles and Joints

PS #1 due

PROBLEM SET #2: Pressure at Depth

Tuesday 9/21: All day in the field

LAB #2: Primary Structures (*field trip*)

LAB #1 due

Thursday 9/23: Fracture Geometries and Failure Envelopes

PS #2 due

PROBLEM SET #3: Mohr Circle problem

Tuesday 9/28: Fault Geometries

LAB #3: Fractures (*field trip*)

LAB #2 due

III. Ductile Structures (Chapters 7 and 8)

Thursday 9/30: Folds

PS #3 due

PROBLEM SET #4: Beta Diagrams

Tuesday 10/5: Foliation and Lineation

LAB #4: Foliation and Lineation, part 1 (*field trip*)

LAB #3 due

Thursday 10/7: Multiple Deformation Events

PS #4 due

Saturday 10/9: OPTIONAL FIELD TRIP all day long

Tuesday 10/12: MID-SEMESTER BREAK

Thursday 10/14: Multiple Deformation Events

PROBLEM SET #5: Rotation on a Stereonet (Part III section I)

IV. Kinematic Analysis and Strain (Chapters 2 and 9)

Tuesday 10/19: Strain and Kinematics

LAB #5: Foliation and Lineation, part 2 (*field trip*)

LAB #4 due

Thursday 10/21: Shear Zones

PS #5 due

PROBLEM SET #6: Pure Shear vs. Simple Shear

Tuesday 10/26: Kinematic Indicators

LAB #6: Kinematic Indicators (*field trip*)

LAB #5 due

Thursday 10/28: Strain Analysis

PS #6 due

PROBLEM SET #7: Strain Rates

Tuesday 11/2: 3D Strain

LAB #7: Experiments

LAB #6 due

Thursday 11/4: CLASS CANCELLED

Tuesday 11/9: CLASS CANCELLED

Thursday 11/11: CLASS CANCELLED

V. Orogenesis (Chapters 4 and 10)

Tuesday 11/16: Dislocations and Recrystallization

LAB TIME: Introduction to the Alps

LAB #7 due

Thursday 11/18: Diffusion and Deformation Mechanism Maps

PS #7 due

Tuesday 11/23: Rock Strength

LAB CANCELLED FOR THANKSGIVING

Thursday 11/25: THANKSGIVING

Tuesday 11/30: First Oral Presentations

LAB TIME: First Oral Presentations

Thursday 12/2: PTt paths and Isotopic Systems

Tuesday 12/7: Second Oral Presentations

LAB TIME: Second Oral Presentations

Thursday 12/9: Dating Shear Zone Development with Getty and Gromet

Tuesday 12/14: Dating Multiple Deformation Events with Monazite

LAB TIME: Peer Review of Final Papers

Tuesday 12/21: Final draft of final paper due

Labs: guidelines for writing about the results of your research

--Try not to exceed the one page limit. One page means one 8.5 x 11 page with 1 inch margins, 1.5-spaced text, using a 12 point font such as Times.

--If you are writing about the results of field research, carefully describe the rock types (lithologies) you examined.

--Use tables to present your raw data on the orientations of various structures. Label each table and its column headings carefully (for example, Table 1: measurements of the orientation of primary and secondary features, including column headings like strike and dip of bedding, and trend and plunge of amphibole lineation).

--Use figures to clarify your arguments and present visually your results. Refer to each figure in the text of your one-page write-up, and label and title each figure.

For example:

Figure 1 shows that foliation is subhorizontal at the western end of the roadcut, although the orientation of schist foliation varies locally. Pegmatite veins consistently crosscut this schist foliation (Figure 2).

These statements are appropriate if the label to Figure 1 reads Figure 1: Equal angle stereographic projection of poles to schist foliation surfaces, western side of the roadcut, and the label to Figure 2 reads Figure 2: sketch of intrusive contact between schist and pegmatite, with 1 meter bar for scale.

--Write clearly and use scientific language (try reading your text if you lack vocabulary). Use the active voice whenever possible.

For example: During pure shear, a line with an initial orientation of 45° to the positive x axis experiences elongation and clockwise rotation.

--Elaborate on your observations and results. Spend the bare minimum of time on descriptions of how you made these observations.

For example: In general, bedding strikes east-west and dips ca. 30° to the north. Cylindrical open folds locally reorient bedding. b diagrams (Figure 1) show that fold axes trend north-south and plunge shallowly to the north.

--Remember that you are identifying plausible explanations for patterns in the data you collected. Think creatively, and justify your arguments and conclusions carefully.

For example: Joints tend to strike east-west, and this single orientation for the many joint surfaces is most consistent with predictions from the tensile fracture criterion (critical sn is constant). Joint geometry therefore suggests that this joint system developed in tension. This hypothesis, however, does not explain the few joints I observed that strike north-south. Joints in these orientations may result from...

--Discuss your results positively and consider the broad implications of your research rather than berating yourself or speculating about research you did not conduct.

For example: During the strike-slip experiment, fracturing occurred first along the edge of the block near my thumb imprint. This observation suggests that brittle structures such as fractures may nucleate at perturbations or inhomogeneities in materials.

Good scientific writing requires clear presentation of research and succinct and creative discussion of ideas. Please follow these guidelines.

Guidelines for Final Paper

You MUST bring two copies of your first draft of your final paper to lab on

Tuesday December 14 in order to review it with your peers.

The final draft of your final paper is due under my office door on Tuesday December 21.

Attached MUST be the two copies of peer reviewed first drafts

Paper format

Typed and three pages long. Three pages means three 8.5 x 11 pages with 1 inch margins, 1.5-spaced text, using a 12 point font such as Times. The format and organization of your paper are up to you to decide, but you should include subheadings (like any published article in the Journal of Structural Geology).

Topics

Please choose one of the following topics:

--Identify an unresolved question about the Alps that is geological, geophysical, or tectonic. Convince your reader that this question is interesting. Propose a research project that addresses this problem.

--Identify and discuss a conflict between the observations and/or interpretations in some of the articles. What is the nature of this conflict (i.e. does it relate to conflicting observations or interpretations)? Do you foresee any resolution to the conflict?

--Identify and discuss a common observation in some of the articles. Discuss the consequences of this observation for either structural or regional geologists.

--The most exciting geological, geophysical, or tectonic epiphany I had during oral presentations was...

Citations

Use five or more references from the articles presented (Markley, 2002). You may use your two articles, although this is not required. In other words, you must reference and discuss at least three other presentations. In the "References" section below, Markley (2002) gives an example of the citation style you should use for your reference list.

References

Markley, M. J., 2002, Guidelines for research papers. Journal of Fabulous Pedagogy v.1, p. 876-876.