Subduction Flashcards
What is the cause of the Subduction Mountains?
Compressional stress
Where are the Subduction Mountains located?
Oceanic subduction zones (Japan)
Continental Subduction zones (Andes)
Forms where ocean crust goes down a trench
Accretionary Wedge
Thrust slices pile up over time with the youngest slice added at the ___
Base
Are fold and thrust zones unique to subduction?
No, it also occurs in a collision
Where the rocks are hotter and can slide a long distance, you get:
A fold and thrust belt
A mix of strong and weak rocks make:
Both folds and faults
Unique to continental subduction
Suspect Terranes
Smaller continents get dragged toward the trench
Suspect Terranes
They can’t subduct so they get added on instead
Suspect Terranes
When two large continents collide, they make wide and very complicated mountain belts.
Collision Mountains
Different compressional folds and faults form at different locations and depths
Collision Mountains
Bring ocean rocks to mountain tops
Thrust faults
Form deep underground
Large recumbent folds
To remove the ocean between two continents what do you need on at least one side
Subduction
Volcanic mountains deform rocks before the continents collide
Active Margin
Quiet and undisturbed until it tries to go down the trench
Passive Margin
Unique to collision
Suture Zone
Ultramafic rocks end up smashed between the two continents, marking the former ocean
Suture Zone
Folds and thrusts form on both sides of the:
Suture
Deformation is worse on the side that tried to subduct =
The former passive margin
Result of being under the two plates of collision
A much wider and deeper fold and thrust best than in subduction zones
Fault blocks appear to rise up as mountains, but they are really sinking
Rift valleys
Rifting Mountains
Can occur over a narrow or wide region
Rifting Mountains
Allow valleys to sink along facing foot walls
Normal faults
Ranges made from basin and range terrain
Horsts
Basins made by basin and range terrain
Grabens
One valley breaks through the crust forming a new ocean
Typical Rift
Hundreds of valleys form but none break through the crust
Soft Rifting
