Introduction to structural geology Flashcards
Structure
A geometric configuration of rocks
Structural Geology
The study of structures created by deformation of rocks
Tectonics
Combining many structural geology observations to interpret regional scale processes
Example of deformation structures (3)
- Fault
- Fold
- Joint
Seismic Exploration
The use of seismic wave to map under the surface
GPS uses
Are used to monitor plate tectonic motion (you put a gps on the ground and record data as its moving)
(3) Factors to combined in the study of structural geology
- Geometry
- Kinematic
- Dynamic
Geometric Analysis
- Shape, Orientation, Size of structures
- Relationship between hierarchical structures
Kinematic Analysis
Relative movement of particles
Strain accumulates progressively: finite strain = sum of many increments
Dynamic analysis
Concider the forces that cause displacement and deformation
Stress is the magnitude of forces acting on a point
rheology describes how a material responds to applied forces
Rheology
how material react to stress
Tectonic Interpretations
models that we present with maps, cross sections and stereonets
Rake (pitch)
Measure the plane containing the line
measure the angle from horizontal
True Dip
angle as measured perpendicular to strike
Apparent dip
smaller than true dip
Formula to get apparent dip from true dip
a=arctan((tan(d))(sin(b))) where
a=apparent dip
d=true dip
b=angle between strike of plane of interest and cross section line
Primary Structure
Characteristic of rock when they form (not a deformation)
Deformation
any combination of Rotation, Translation, Distortion, volume change
Deformation takes TIME
Why do rocks deform
Because of Plate Tectonics
Relative Motion (Displacement)
When a force is applied the ends move apart. We only see the final stage, we don’t see when the deformation happens
Displacement Vectors
each particle in the body we examine moves and they each get a vector
It characterizes before and after, the displacement and the approximate path taken
Homogeneous and heterogeneous deformation
we assume that rocks deform as a continuum of particles
Deformation may vary, but it doesn
Deformation matrix
Describes the new position of a point in terms of its original position
