3 plate tectonics part two

Question 1

Lithosphere and athenosphere

Answer 1

Lithosphere
Rigid (but can bend if there’s a heavy load)
Made up of crust and upper mantle
Asthenosphere
Partly molten
Soft
Able to flow

Question 2

basic temp and density physics

Answer 2

Heat rises
Density decreases
Cold sinks
Density increases

Question 3

What provides the motion of liquidish in the asthenosphere

Answer 3

probably not just convection: more complicated see screenshot of warm and cool zones

Question 4

which came first ridge push or slab pull

Answer 4

The chicken (ridge push)
The spreading at the ridges
The egg (slab pull)
The sinking at the subduction zones

Current thinking
Probably slab pull started the cycle of plate tectonics, but… we don’t know

Question 5

Earth’s plates

Answer 5

7 main plates: Pacific, Eurasian, African, Antarctic, Indian-Australian, North American, South American

Question 6

Plate boundaries divergent

Answer 6

divergent
Plates moving apart
Types:
Oceanic
Continental

Question 7

plate boundaries convergent

Answer 7

Convergent
Plates moving together
Types:
Continental – Oceanic
Oceanic – Oceanic
Continental - Continental

Question 8

plate boundaries transform

Answer 8

Transform
Plates sliding past each other
Types:
Continental
Oceanic

Question 9

crust is created and destroyed where?

Answer 9

Crust is created at divergent plate boundaries
Crust is destroyed at convergent plate boundaries

Question 10

divergent mid ocean ridge

Answer 10

Plates moving apart

Major features:
Volcanic rise
Central rift valley (“rift axis”)
Faults

Examples:
East Pacific Rise
Mid-Atlantic Ridge

Question 11

divergent continental rifts

Answer 11

Parts of a continent moving apart

Major features:
Volcanism
Faulting
Eventually seafloor creation

Examples:
East African Rift-Red Sea
Our backyard

Question 12

basin and range(our backyard)

Answer 12

Narrow north-south-trending mountains separated by basins
Horst = Mountain range
Graben = Valley See screenshots to describe these boundaries

Question 13

convergence key principle oceanic vs continental

Answer 13

Oceanic crust
Younger
Denser
Sinks into the asthenosphere

Continental
Older
Less dense
Will NOT sink into the asthenosphere

Question 14

convergent: continental-oceanic and earthquake evidence

Answer 14

Plates moving together
Light vs Dense

Major features:
Continental volcanic arc
Trench
Accretionary prism

Examples:
Andes
Cascadia
Aleutian Islands

earthquake evidence : Earthquake depths
Increasing depth of earthquake away from trench
Wadati-Benioff Zone

Question 15

convergent: oceanic-oceanic

Answer 15

Plates moving together
Dense vs denser

Major features:
Island volcanic arc
Trench
Small accretionary prism

Example:
IBM Arc (Izu-Bonin-Mariana)

Question 16

convergent continental-continental

Answer 16

Plates moving together
Light vs light

Major features
Folded mountain belts

Examples
Himalayas
Ancient Appalachians

Question 17

Transform plate boundaries

Answer 17

Sideways motion
Link between other types of boundaries

Major features:
Crust deformed
Not created, not destroyed
Fracture zones

Example:
San Andreas Fault
Between ocean ridge segments
Dead Sea

Question 18

convergent boundaries can turn from continental-oceanic to continental continental if all fo the ocean is moved beneath and continental plates connect

Answer 18

true blue write it out

Question 19

mantle plumes

Answer 19

Mantle plumes and hotspot volcanoes
Mantle plume
Rising column of molten rock through the mantle and lithosphere
**Does NOT move relative to the plates’ motions

Question 20

whys

Answer 20

Why does new oceanic floor get generated at the ocean ridges?
Why does old oceanic floor get pushed and destroyed at the ocean trenches?
Why do the plates move?
When did it all start?