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Society of Earth Science Students
A student-run club for all students interested in Earth Science, regardless of major.
Activities: field trips, weekly speakers, outreach to kids and adults, and the Tucson Gem and Mineral Show Junior Education area
Meetings:Fridays 1:00 pm Gould-SimpsonBuilding Room 209
Society of Earth Science Students
Meetings:Fridays 1:00 pm Gould-SimpsonBuilding Room 209
Some past trips:• Pinacate volcanic field, Mexico• Grand Canyon• Kartchner Caverns• Moonlight hikes
Society of Earth Science Students
Meetings:Fridays 1:00 pm Gould-SimpsonBuilding Room 209
Tucson Gem and Mineral Show
Society of Earth Science Students
Meetings:Fridays 1:00 pm Gould-SimpsonBuilding Room 209
Come to the meetingsJoin the field trips
www.geo.arizona.edu/SESS
Free pizza and soda at the first meeting!
Friday September 6th
(Chapter 1 in D & R)(Chapter 1 in D & R)
Overview of Structural GeologyOverview of Structural Geology
OUTLINEOUTLINE 1) What is structural geology?1) What is structural geology?
2) What are structures?2) What are structures? 3) Goals of structural analysis3) Goals of structural analysis
4) Intro. Geometry4) Intro. Geometry
What is structural geology?
- Study of rock deformation, “the study of the architecture of the Earth’s crust”
- “forensic science”
Why is structural geology important? - Fundamental to Earth Science
- Insight about planetary evolution
- Relations between tectonics and climate
- Natural hazards- Resource exploration and management
What skills will be practiced?
- Scientific method- 3-D Visualization and presentation
- Mapping- Quantitative
- Integrating multiple disciplines
What are structures?Two main types:
(1) Primary structures: Develop during formation of a rock body; e.g.,cross-bedding, ripple marks, mudcracks, pillows (in basalt)
(2) Secondary structures: Form in rocks as a result of deformation- the structures this class are focused on!
Secondary Structures
Devil’s Postpile, Sierra Nevada, CA
Joints: fractures with very little or no displacement
Veins: fractures filled with minerals
Secondary Structures cont.
Faults: fractures that have accommodated displacement
Folds: systematically curved layers
Secondary Structures cont.
Cleavage: closely spaced subparallelsurfaces that impart a splitting property
Foliation: very closely spaced subparallel planar features
Goals of Structural AnalysisGoals of Structural Analysis
Geometry:Geometry: mapping, measurements mapping, measurements
Kinematics:Kinematics: movements related to deformation movements related to deformation– Translation: change in positionTranslation: change in position– Rotation: change in orientationRotation: change in orientation
– Distortion: change in shapeDistortion: change in shape– Dilation: change in volumeDilation: change in volume
Dynamics/Mechanics:Dynamics/Mechanics: relating deformation to relating deformation to stressesstresses
Intro. Geometry: Structural measurementsIntro. Geometry: Structural measurementsTools: compass and protractorTools: compass and protractor
Planar structuresPlanar structures Strike: compass direction of trace of horizontal line on a plane; Strike: compass direction of trace of horizontal line on a plane;
bearing (quadrant, E or W of north) or azimuth (degrees bearing (quadrant, E or W of north) or azimuth (degrees clockwise from N)clockwise from N)
Dip: inclination of plane from horizontal, perpendicular to Dip: inclination of plane from horizontal, perpendicular to strikestrike
Linear structuresLinear structures Trend: direction of a vertical plane that Trend: direction of a vertical plane that
contains the linear feature in the direction of contains the linear feature in the direction of plunge.plunge.
Plunge: angle between line and horizontalPlunge: angle between line and horizontal
Next Lecture:Next Lecture: Geometry and kinematics ofGeometry and kinematics oflarge-scale deformation- Plate Tectonicslarge-scale deformation- Plate Tectonics
Read Chapter 10 in Davis and ReynoldsRead Chapter 10 in Davis and Reynolds
Important terminology/conceptsImportant terminology/concepts
- Structural geology- what is it and why is it important?- Structural geology- what is it and why is it important?
- Primary structures vs. Secondary structures- Primary structures vs. Secondary structures
- Joints- Joints
- Veins- Veins
- Faults- Faults
- Folds- Folds
- Cleavage- Cleavage
- Foliation- Foliation
- Shear zones- Shear zones
- Lineations- Lineations
- Structural analysis- Structural analysis
- Planar features: strike and dip- Planar features: strike and dip
- Linear features: trend and plunge- Linear features: trend and plunge