Tectonic Plates - Unit 1
Tectonic Plates:
- What are the lithosphere and the asthenosphere?
- Lithosphere is primarily crust and the very very top part of the mantle.
- Athenosphere is more malable part of the the mantle. Lithosphere is brittle.
Athenosphere is solid, but can be moved and manipulated by tectonic forces. Like
a softened caramel.
- From top to bottom Continental crust - Lithospheric mantle - Asthenosphere
- How are continental and oceanic plates similiar and different?
- Continental plate is thicker and less dense
- Continental Lithosphere is more varied. Granite, etc.
- Oceanic Lithosphere is comprised primarily of Basalt
- Oceanic crust is thinner but tends to be dense. This is because of oceanic pressure
which increases temperatures of the crust and makes it thinner. More volcanic
activity because of this as well.
- What are the types of plate boundaries?
- Divergent Boundaries - Mid ocean ridges are always the result of divergent
boundaries. Even though they separate, they create mountains under the ocean
due to magma rising up and pushing up material and magma.
- Convergent Boundaries - volcanoes are common, 3 different kinds. Ocean on
ocean, ocean on continental, continental on continental
- Ocean Ocean - one is forced underneath, the one that goes under does not
immediately melt. It must heat up over a long time far below, the pressure
is so causes it to liquify, or certain materials retain water. When water gets
hot enough it can cause melting at points it normally wouldn’t have
happened. This happens once it is forced far enough down to boil the
water.
- Ocean trenches are created by the snagging of the very edge of the
winning plate. This creates an ocean trench which accounts for the
deepest points of the ocean. The volcanic area is offset slightly
more into the winning plate.
-
- Ocean Continent - Ocean Lithosphere always goes under the continental.
This is like the ocean to ocean, but the resulting volcanic activity creates
things like andesite, due to different composition.
- Continent Continent - Starts as an ocean to continent and then runs out of
ocean, then the two continents are all that is left to collide.
- N
either are dense so neither plate will subduct, this creates
mountains as they smoosh together.
- Most earthquakes of all convergent boundaries.
- Mountain ranges create a lot of weight on the lithosphere and force
it down.
- Mountains begin eroding and this causes the lithosphere to rise
- Transform Fault / Transform Boundary (Sliding) - most occur on mid-ocean
ridges
- Hot Spot Volcanism:
- Certain material rises through the mantle. Scientifically unexplained.
- Volcanoes are covered later, likely not on the quiz.
- Could be explained by exceptionally hot points in the mantle underneath
weaker parts of the athenosphere and lithosphere.
What are the 3 types of convergent boundaries (with details)
volcanoes common, 3 different kinds. Ocean on ocean, ocean on continental, continental
on continental
What features and hazards would you expect to find at each type, typically?
Divergent Boundaries
- Features: Rift valleys (on land) and mid-ocean ridges(under the ocean).
- Hazards: Volcanic activity as magma rises to fillthe gap, shallow earthquakes, and the creation
of new crust.
Convergent Boundaries
- Features: Deep ocean trenches, volcanic island arcs,continental mountain ranges.
- Hazards: Powerful earthquakes, volcanic eruptions,and potentially tsunamis, especially where
one plate subducts beneath another.
Transform Boundaries
- Features: Fault lines as plates grind past eachother.
- Hazards: Frequent, shallow earthquakes caused by the buildup and sudden release of pressure
between the sliding plates. Little to no volcanic activity or major mountain formation
- W
hat drives tectonic plates?
The heating of the earth’s core and gravity. The Earth core heats from radioactive
materials.
- Mid ocean ridges are longest mountain ranges on earth and are located under the ocean
rofessor doesn’t care about people, only their discoveries and scientific contributions. Explain
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concepts and how they work.
Magnetic aspect to the formation of ridges?
- Magnetic striping is how we can tell that plates are moving apart from each other.
Types of plate interaction:
Convergent
Divergent
Transform
Earthquakes tend to be around the plate boundaries and are a result of lithospheric forces
Lithospheric plates ARE Tectonic plates.
ayers:
L
SURFACE -> Lithosphere (Crust) -> Athenosphere (Absolute uppermost part of the mantle) ->
Mantle -> Core
asalt is high in iron. It is magnetic. AKA Igneous rocks. Magnetic Striping is where the
B
magnetic field of a non-solid rock is locked in when it turns solid. They seperate in the middle
and this provides proof that the two plates are moving apart.
he Core is hot because of radioactive decay. Different radioactive materials decay and react in
T
the core, it heats up, and melts rock. Hints, magma.
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