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Diastrophism

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kzoe1996

This document discusses different types of landforming processes caused by stress and strain on rocks. It describes three main types of deformation - folding, faulting, and fracturing. Folds form from compressional stress causing rocks to buckle into arches (anticlines) or sinks (synclines). Faults form when rocks fracture from strain, with one side displaced relative to the other along the fault plane. The main types of faults are normal, reverse, thrust, transform, and oblique-slip faults, which result from different types of differential stress.

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Landforming Processes: DIASTROP HISM
Stress and Strain •Stress is force acting on rock •Strain is rock’s response to stress When a rock is subjected to stress, it deforms and is said to strain. A strain is a change in size, shape, or volume of a material. Uniform Stress – is a stress wherein all the forces act equally from all directions Differential Stress – occurs when stress acting on the rock is not equal in all directions
Tensional stress (or extensional stress) – stress which stretches rock Compressional stress – stress which squeezes rock Shear stress – stress which results in slippage and translation Three Kinds of Differential Stress
Diastrophism
1. Folds 2. Faults Types of Deformation WhenTypes of Deformation When Rocks are Subjected to StressRocks are Subjected to Stress
FOLDING • Compressional stress causes rocks to buckle and fold – Anticline: arch-shaped fold – Syncline: sink-shaped fold
Anticlines begin as ridges Synclines begin as valleys
Diastrophism
FAULTING • Rock is strained beyond ability to remain intact; rock fractures; one side is displaced with respect to the other . Fault plane: surface along which 2 sides move Fault scarp: cliff formed along fault face
Diastrophism
The two sides of a non- vertical fault are known as the hanging wall and footwall. hanging wall occurs above the fault plane footwall occurs below the fault
Types of FAULTS 1. Normal Fault - results from extensional stress - vertical movement along an inclined fault plane
Diastrophism
HORST and GRABENHORST and GRABEN (result of normal faulting)(result of normal faulting) Graben down-faulted block Horst up-faulted block
Diastrophism
2. Reverse Fault - results from compressional stress - Vertical movement along inclined fault plane such that one side rides up over the other. - often creates landslides
Diastrophism
3. Thrust fault - reverse fault with very low angle - more horizontal than vertical movement
Diastrophism
4. Transform(Strike-slip) Fault - horizontal movement; no fault scarp
Diastrophism
5. Oblique-slip faults - have both a vertical and horizontal component of motion along the fault - adjacent points on different sides of the fault have moved up or down and back or forward relative to each other. They are essentially a combination of strike-slip and dip-slip motion.

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Diastrophism

  • 2. Stress and Strain •Stress is force acting on rock •Strain is rock’s response to stress When a rock is subjected to stress, it deforms and is said to strain. A strain is a change in size, shape, or volume of a material. Uniform Stress – is a stress wherein all the forces act equally from all directions Differential Stress – occurs when stress acting on the rock is not equal in all directions
  • 3. Tensional stress (or extensional stress) – stress which stretches rock Compressional stress – stress which squeezes rock Shear stress – stress which results in slippage and translation Three Kinds of Differential Stress
  • 5. 1. Folds 2. Faults Types of Deformation WhenTypes of Deformation When Rocks are Subjected to StressRocks are Subjected to Stress
  • 6. FOLDING • Compressional stress causes rocks to buckle and fold – Anticline: arch-shaped fold – Syncline: sink-shaped fold
  • 7. Anticlines begin as ridges Synclines begin as valleys
  • 9. FAULTING • Rock is strained beyond ability to remain intact; rock fractures; one side is displaced with respect to the other . Fault plane: surface along which 2 sides move Fault scarp: cliff formed along fault face
  • 11. The two sides of a non- vertical fault are known as the hanging wall and footwall. hanging wall occurs above the fault plane footwall occurs below the fault
  • 12. Types of FAULTS 1. Normal Fault - results from extensional stress - vertical movement along an inclined fault plane
  • 14. HORST and GRABENHORST and GRABEN (result of normal faulting)(result of normal faulting) Graben down-faulted block Horst up-faulted block
  • 16. 2. Reverse Fault - results from compressional stress - Vertical movement along inclined fault plane such that one side rides up over the other. - often creates landslides
  • 18. 3. Thrust fault - reverse fault with very low angle - more horizontal than vertical movement
  • 20. 4. Transform(Strike-slip) Fault - horizontal movement; no fault scarp
  • 22. 5. Oblique-slip faults - have both a vertical and horizontal component of motion along the fault - adjacent points on different sides of the fault have moved up or down and back or forward relative to each other. They are essentially a combination of strike-slip and dip-slip motion.