Crustal Deformation and Orogenesis

Question 1

What are the 5 tectonic features?

Answer 1

1. Trench
2. Hot Spot
3. Mid-Oceanic Ridge
4. Mountain
5. Ridge

Question 2

What type of boundary causes a Trench?

Answer 2

Convergent Boundary

Question 3

What type of boundary causes a Mid-Oceanic Ridge?

Answer 3

Divergent Boundary

Question 4

What type of boundary causes a Mountain?

Answer 4

Convergent Boundary

Question 5

Describe Crustal Deformation

Answer 5

Pressures resulting from tectonics, gravity and weight of overlying material that can lead to deformation/ changes of the earth’s surface’s features

Question 6

Crustal Deformation arises from what 2 considerations?

Answer 6

Composition and Amount of Pressure - together they affect the type of deformation

Question 7

Describe Composition in relation to Crustal Deformation

Answer 7

Composition can be brittle or ductile
Brittle: Faulting- changing by breaking
Ductile: Deformation- changing without breaking

Question 8

What are the 3 possible forces at play in plate boundaries?

Answer 8

1. Tensional forces
2. Horizontal bending
3. Compressional forces

Question 9

Describe Tensional Forces

Answer 9

• Occur at Divergent boundaries (nonbreaking, crustal material begins to thin)
• Faulting at Divergent boundary thins to the point of breakage and then one side drops down away from the other = Normal Fault

Question 10

Describe Horizontal Bending

Answer 10

• Occurs at Transform boundaries
• Horizontal bending= non-breaking
• Shear forces
• Strike-slip Fault

Question 11

Describe Compressional Forces

Answer 11

• Occurs at Convergent boundaries
• Compressional forces = shortening of crustal material
• Folding (non-breaking)
• Reverse Fault = breakage (opposite of Normal fault)

Question 12

What are the 2 types of Folding?

Answer 12

1. Anticline (up)

2. Syncline (down)

Question 13

Define Orogenesis

Answer 13

The birth of mountains

- Convergent plate boundary phenomenon

Question 14

When does Orogenesis occur?

Answer 14

Can occur through folding, warping, crustal uplift and volcanism

Question 15

What is Orogeny?

Answer 15

A mountain building episode

Question 16

What are the 3 types of Orogenies

Answer 16

1. Oceanic-Continental
2. Oceanic-Oceanic
3. Continental-Continental

Question 17

What is a Thermal Orogeny?

Answer 17

Orogeny made from Igneous activity (melting rock) occurs in Oceanic-Continental orogeny

Question 18

What is a Mechanical Orogeny?

Answer 18

Orogeny made from non-Igneous (non-melting) activity

Occurs in Continental-Continental orogeny

Question 19

Describe Oceanic-Continental Orogenies

Answer 19

Ocean plate subducts under continental plate

• Thermal Orogeny (subducted plate melts, migrates back toward surface with volcanic activity inland of subduction and granitic batholiths at the base of mountains)
• Shortening
• Plate Subduction (related to it being thermal)
• Folding
• Igneous, Sedimentary, Metamorphic
• Folded Sedimentary formations
• Mountain on the edge of a continent

Question 20

Describe Oceanic-Oceanic Orogenies

Answer 20

Ocean plate subducts under another ocean plate

• Compression forces
• Thermal Orogeny (subducted plate melts, migrates back toward surface)
• Simple volcanic island arcs form on overriding plate
• Material melts, comes up to surface (volcanic island) inward from trench
• Folding, warping (chains of small islands)
• Igneous rock
• Volcanoes

Question 21

Describe Continental-Continental Orogenies

Answer 21

-Mechanical
-Collision of large masses of continental crust
-Thick crustal material
-Crust shortening but no subduction
Intense folding, uplift, overthrusting and faulting
-no volcanic activity