Plate tectonics Flashcards
After midterm 1
Which is more dense, a continental plate or oceanic plate
Oceanic plate is more dense - 3.0g/cm^3
Continental plate is less dense - 2.7g/cm^3
Oceanic plates are composed of what type of rock
Basaltic rock
Continental plates are composed of what type of rock
silica rich
At what rate do lithospheric plates move
cm/year
What are the 3 types of lithospheric plate boundaries
Divergent, convergent, transform
Are divergent boundaries tension or compression
Tension
Do divergent boundaries create r destroy crust
they’re constructive, so they create crust
in divergent boundaries, new lithosphere can be created by what
volcanism
What is an example of a divergent plate boundary rift valley
east-African rift valley
Divergent plate boundaries typically create continental or oceanic crust
oceanic crust
The mid-Atlantic ridge is what type of boundary
ocean-ocean divergent
Why is there a lot of volcanic activity in Iceland
the mid-Atlantic ridge passes through it
What kind of deposits do we find at divergent plate boundaries
metal deposits
Is convergent plate boundaries compression or tension
Compressions, they’re in collision
Convergent:
the_______ plate is forced beneath the other and down into
the mantle, this process is known as subduction
denser
Do subduction zones have shallow or deep earthquakes
Both
Is mt Fuji and Mt St Helens on a divergent or convergent boundary
convergent, its at a subduction zone
Do convergent or divergent have higher heat flow?
Divergent has a high heat flow. Convergent has a low heat flow. Relative to the geothermal gradient
if we have a oceanic-oceanic boundary, which plate will subduct
the cooler and more dense one
Oceanic-oceanic can cause: a trench, volcanism, islands arcs
All of those
Which type of convergent boundaries are most powerful
oceanic-continental
continental-continental
Which type of convergent boundary does subduction not occur
continent-continent
instead mountains are built
The Alps and Himalayas are examples of what type of plate boundary
Convergent continental-continental
Which type of convergent boundary has little to no volcanism
continent-continent
Which type of boundary does lithospheric material neither be created nor consumed
Transform
Are the earthquakes from transform boundaries shallow or deep? and what is their intensity
Shallow but destructive earthquakes
Which of the following occurs at a transform boundary: subduction, volcanism, trench, earthquakes
earthquakes
transform faults are generally found ____________ to divergent ocean
rift zones such as the Mid-Atlantic ridge
perpendicular
Are hot spots associated with plate boundaries
No
Describe how hotspots work
Mantle plume: upwelling of hot rocks
in convectional cells in the mantle to
the base of the lithosphere
Heat from the plume melts overlying
rocks and magma seeps up to surface
creating a volcano.
Hot spots leave clues and can tell us about the movement of ______
plates
Can use _______ evidence to work out direction, speed of plate movement over time
hotspot
