Crustal Deformation
Cards (6)
- Types of Deformation:
- Brittle Deformation:
- Occurs abruptly or at lower temperatures.
- Results in fracturing or forming faults.
- Ductile Deformation:
- Occurs gradually over time or at higher temperatures.
- Results in bending or forming folds without fracturing.
- Faults: Structures Formed by Brittle Deformation
- Faults are fractures in rock layers where noticeable movement has occurred.
- Key Components:
- Footwall: Rocks below the fault plane.
- Hanging Wall: Rocks above the fault plane.
- Types of Faults
- Dip-Slip Faults:
- Characterized by vertical motion along the fault plane.
- Classified as:
- Normal Fault:
- Hanging wall moves down relative to the footwall.
- Common in divergent boundaries (tensional stress).
- Reverse Fault:
- Hanging wall moves up relative to the footwall.
- Common in convergent boundaries(compressional stress).
- Thrust Fault: A type of reverse fault with a low angle of inclination.
- Strike-Slip Faults:
- Nearly vertical with horizontal (sideways) movement.
- Result from shearing stress, common in transform plate boundaries.
- Folds - are wave-like structures in layers of rocks formed under compressional stress.
- Types of Folds:
- Domes (Anticlinal):
- Shaped like an arch; oldest rocks at the center.
- Formed by upfolding of sedimentary layers.
- Basins (Synclinal):
- Shaped like a basin; youngest rocks at the center.
- Formed by downward folding of rock layers.
- Monoclines:
- Simple folds with slight bends on one side.
- Older layers remain at the bottom, younger ones on top.
- Faults vs. Folds:
- Faults are created through brittle deformation; folds form through ductile deformation.
- Types of Faults:
- Dip-Slip Faults: Normal and Reverse (including Thrust).
- Strike-Slip Faults: Horizontal movement.
- Types of Folds:
- Synclines: Youngest rocks at the center (basin).
- Anticlines: Oldest rocks at the center (dome).
- Monoclines: Bends on one side of strata.