chapter 2 Flashcards
What is the difference between oceanic and continental crust in terms of composition, thickness, and density?
Oceanic crust:basalt and contains iron…thinner…DENSER….
Continental:mostly granite…thicker…less dense
Compare and contrast a tectonically passive continental margin with a tectonically active continental margin. •-Which has a wider continental shelf?
Passive: Wide, flat continental shelf, gentle continental slope, continental rise
Active:Narrow continental shelf, steep continental slope, trench instead of continental rise
Which U.S. coastline is tectonically active? Tectonically passive?
Active-U.S. West coast
Passive-Gulf and East coast
Compare the continental shelf on the East and West coasts of South America. Which one is wider? Which one is passive?
East coast continental shelf is wider than the west coast continental shelf. The west coast is active and the East coast is passive
Abyssal plains are not commonly found in the Pacific. Why?
There are more abysmal plains in the Atlantic because in the Pacific the trenches trap the sediments as it comes off shore. The seiments get stuck in the trenches and does not reach the open ocean basin floor and thus does not have the opportunity to create abysmal plain
What is a submarine canyon?
Canyone that is sliced into the side of a continental slope
What forces are involved in the formation of a submarine canyon
Eroded by turbidity currents
where are submarine canyons found
May be extensions of continental stream valleys
Describe a turbidity current
Down-slope movement of water and sediment…underwater avalanche…and deposit submarine fans
Describe a submarine fan
Found on continental rise at base of submarine canyon•Fan shape deposit•Formed from turbidity currents
What is a seamount?
Volcanoes active or extinct taller than 100 meters
Describe the formation of a coral atoll
Forms from coral build up on volcanoes•Volcano sinks
What is seafloor spreading?
The oceanic lithosphere spreads from the central axis (the ridge is the axis)•Creates new oceanic lithosphere
What is subduction? Draw a cross section of a subduction zone.
Denser plate subducts(is pushed) under less dense plate•Deep sea trenchforms where 2 plates meet•Subducting plate partially melts-creating a chain of island volcanoes parallel to the trench called a volcanic island arc
Divergent plate boundaries
Which way are the plates moving relative to each other?
Plates move away from each other ← → (seafloor spreading occurs here
Divergent plate boundaries
What type of lithosphere is created?
Forms Mid Ocean ridges…mid atlantic ridge, East Pacific Rise, …..new ocean crust is formed
Divergent plate boundaries
What is a hydrothermal vent? Where are they found?
Hydrothermal vent is: underwater hot spring, rich in mineral and chemicals.
Life at the bottom chemosynthetic uses chemicals and heat to survive
Black
What is a black smoker?
The hottest of the hydrothermal vents•Contain dissolved metals that make the water dark•Home to diverse communities of marine life
Are there earthquakes or volcanoes at divergent boundaries?
Yes, there are Earthquakes and volcanic activity in the form of non-explosive lava flows
-Name 2 examples of a divergent plate boundary
Mid Atlantic Ridge, East Pacific Rise
What happens to age of the ocean floor, and depth, and heat flow from the mantle as you move away from a mid-ocean ridge? Divergent plate boundary
Gets older
Which way are convergent plates moving
towards eachother
What are the three types of convergent plates
Oceanic-oceanic convergent–Oceanic-continental convergent–Continental-continental convergent
Oceanic-Oceanic Converging
Which plate subducts
What happens to the subducting plate?
Oceanic crust is destroyed•The denser plate subducts(always oceanic)
Denser plate subducts(is pushed) under less dense plate•Deep sea trenchforms where 2 plates meet•Subducting plate partially melts-creating a chain of island volcanoes parallel to the trench called a volcanic island arc
How does an Island Arc form?
Subducting plate partially melts-creating a chain of island volcanoes parallel to the trench called a volcanic island arc
Where does a deep sea trench form?
deep sea trench forms where two plates meet
Where is the deepest place on the ocean floor Oceanic-Oceanic Converging?
trench
Is the lithosphere created or destroyed Oceanic-Oceanic Converging?
destroyed
Are there earthquakes and volcanoes Oceanic-Oceanic Converging?
yes and yes
Two examples of Oceanic-Oceanic Converging?
A-Aleutian IslandsJ-Japan
What is a oceanic-continental subduction zone
Denser plate subducts under the less dense plate
What happens to the subducting plate oceanic-continental
Subducting plate partially melts-creating a chain of island volcanoes parallel to the trench called a volcanic island arc
How does a continental arc form oceanic-continental
Subducting plate partially melts-creating a chain of volcanoes parallel to the trench called a volcanic arc (not an island because these occur on coastlines, not in the middle of the ocean)
Where does the oceanic trench develop with an oceanic-continental
where to plates meet parallel to the coast line
Is the lithosphere created or destroyed with oceanic-continental
destroyed
Are there earthquakes and volcanoes oceanic-continental?
yes
Two examples of oceanic-continental
Andes mountains, Cascades
Does a continental-continental have a subduction zone?
no subduction zone
Are there volcanoes with a continental-continental?
No
Are there earthquakes or volcanic activity with continental-continental?
Earthquakes but no volcano
Is lithosphere created or destroyed or neither? with continental-continental
Colliding crust pushes upward creating mountain ranges
two examples of continental-continental
Himalayas and Alps
Transform plate boundary:
Which way are the plates moving relative to each other?
Plate slide past each other
Volcanoes with transform plate boundaries?
No volcanoes
Earthquakes with transform plate boundaries?
yes
Earth crust created destroyed or neither from transform boundaries?
neither
Example of transform boundary
san andreas fault
Which plate boundaries have earthquakes?
All of them. Divergent, Oceanic-Oceanic Convergent, Oceanic-Continental Convergent, Continental-Continental Convergent, Transform
Which plate boundaries have volcanic activity?
Divergent, Oceanic-Oceanic convergent, Oceanic-Continental convergent
Are the Hawaiian islands a plat boundary?
No
Mantle plume-stationary column of heat from mantle•Plate moves over top of mantle plume•Spot on crust over mantle plume is called a “Hot Spot”
Which direction is the pacific plate moving?
The Pacific Plate moves over the mantle plume. Whichever part of the plate is over the mantle plume has active volcanoes. The volcanoes that have moved away from the mantle plume are extinct.
-Describe how the Hawaiian Islands formed.
The plate moves over the hot spot creating volcanoes and then they move and become extinct.
Which direction is the Pacific Plate moving?
The Pacific Plate is moving towards the North-west.
Which of the Hawaiian Islands is the oldest?
Kauai is the oldest
Which is the Youngest?
The big island of “Hawaii” is the youngest.
What type of plate boundary is Hawaii?
It is not a plate boundary.
Which is closest to the hot spot?
The big island of “Hawaii” is closest to the Hot Spot
How did the Hudson canyon form?
Turbidity current
Active” as in an “active continental margin” does not mean the same thing as “convergent”. If I am asking you for a type of plate boundary, and you say “active,” it will not be acceptable.
The types of plate boundaries are: divergent, oceanic-oceanic convergent, oceanic-continental convergent, continental-continental convergent, and transform. “Active” just means that there is a plate boundary. It doesn’t really mention the type. All of the active continental margins we looked at were convergent though
Which of the following is in the first stage of the Wilson Cycle? Second stage?Atlantic Ocean Red Sea East African Rift Valley
First Stage: East African Rift Valley Second Stage: Red Sea Next Stage: Atlantic Ocean
What is the tectonic setting for Utah? (Are we a plate boundary? If not, what are we?)
intraplate
Which plate boundary is closest to Utah going East? Going West?
Going East-the Mid-Atlantic Ridge Going West-The San Andreas Fault•
