Deformation and Mountain Building Flashcards
Types of deformation
1) Bending.
2) Breaking.
3) Shortening
4) Stretching.
5) Shearing the rocks
Strain
Changes in shape
Deformational strain:
Joints
Folds
Faults
Foliation
Joints
Fractures that have no offset.
Folds
Layers that are bent by slow plastic flow.
Faults
Fractures that are offset.
Foliation
Planar metamorphic fabric.
Deformation results (3)
1) Translation
2) Rotation
3) Distortion
Translation:
change in location
Rotation:
change in orientation
Distortion
change in shape
Strain types (3)
1) Stretching
2) Shortening
3) Shear
Deformation types (2)
1) Brittle
2) Ductile
Ductile
rocks deform by flowing or folding
occur in deeper crust
Higher P and T
Ductile
rocks deform by flowing or folding
occur in deeper crust
Higher P and T
Compression
Compression takes place when an object is squeezed
causes folds to be prominant
Compression
Compression takes place when an object is squeezed
Shear
when two objects rub by one another
causes folds to flatten out
Pressure
occurs when an object feels the same stress on all sides
Pressure
occurs when an object feels the same stress on all sides
Bearing
Compass direction
Plunge
Angle from horizontal
Thrust faults
- older rock on top of newer rock
- common: leading edge of orogenic deformation
- shorten and thicken mountains
Mylonites
Rocks from ductile shear zones
Mylonites
Rocks from ductile shear zones
Hinge
is a line along which the curvature is the greatest
Limbs
less folded “sides” of the curve
Axial plane
connects hinges of successive layers
Syncline
is a fold that opens upward like a trough
Syncline
is a fold that opens upward like a trough.
Monocline
like a carpet draped over a single stair
Dome
Circular landform
is a fold with the appearance of an overturned bowl.
exposes older rock
How do folds develop? (2)
1) Flexural slip
2) Passive flow
How do folds develop? (2)
1) Flexural slip
2) Passive flow
Continental mountain building
caused by thrust faults
fold thrust belts move outward on either side
high mountains may eventually collapse
Orogenesis creates (2)
1) Igneous rock
2) Metamorphic rock
Orogenesis creates (2)
1) Igneous rock
2) Metamorphic rock