MECHANISM OF PLATE TECTONICS: CONVECTION CURRENT, SLAB PULL & RIDGE PUSH | SCIENCE 10 - Week 7
Summary
TLDRThis week's lesson delves into the forces behind plate tectonics: convection currents, slab pull, and ridge push. Convection currents, likened to a conveyor belt, drive plate movement through the sinking and rising of hot and cold materials in the mantle. Slab pull theory attributes plate movement to the gravitational pull of subducting plates, while ridge push, occurring at mid-ocean ridges, is a gravity-driven force where lithosphere slides down the elevated asthenosphere. These mechanisms collectively explain the causes of plate tectonics.
Takeaways
- 🌏 This week's discussion focuses on the possible causes of plate movements, including slab pull, ridge push, and convection currents.
- 🔍 The lesson aims to describe convection current, slab pull, and ridge push, and to explain what causes plate tectonics.
- 🔄 Convection current is likened to a conveyor belt, driving plate movement through the sinking of hot, soft rocks in the asthenosphere, creating a continuous loop.
- 🌋 Convection cells in the mantle are essential for plate tectonics, transferring heat to the surface faster than conduction alone.
- 🌀 Arthur Holmes proposed that convection currents in the mantle cause the plates to move, with heated material rising and cooled material sinking, creating a circling behavior.
- 📉 The slab pull theory suggests that the weight of the tectonic plate itself, through the subduction process, is a driving force for plate tectonics.
- 🌐 The ridge push force is a result of the lithosphere sliding down the slope of the asthenosphere at mid-ocean ridges due to gravity.
- 🌌 The asthenosphere is a less dense, soft, and plastic zone that allows the overriding plate to slide, contributing to plate movement.
- 🏔 The ridge push force increases towards the subduction zone as the plate gets thicker and denser away from the spreading center.
- 📚 The lesson concludes by summarizing the three forces that interact to create plate motion: convection current, slab pull, and ridge push.
Q & A
What are the three forces discussed in the script that interact to create plate motion?
-The three forces discussed are convection current, slab pull, and ridge push.
How does a convection current function in relation to plate tectonics?
-A convection current in plate tectonics refers to the continuous loop of sinking hot, soft rocks caused by energy transfer in the asthenosphere, creating loops of sinking and rising materials in the mantle, which pushes the magma up, forming new crusts and exerting a lateral force on the plate.
What is a convection cell and how does it relate to plate tectonics?
-A convection cell is a circular pattern created by convection within the mantle, where hot material rises and cold material sinks, creating cycles that push the magma up and apart, contributing to seafloor spreading and plate movement.
Who proposed the theory of mantle convection, and what is the essence of this theory?
-Arthur Holmes proposed the theory of mantle convection, which suggests that as the mantle becomes heated, its density decreases, causing it to rise, and when it cools, it sinks, exhibiting a circling behavior that drives plate motion.
What is the slab pull theory and how does it cause plate tectonics?
-The slab pull theory states that the weight of the tectonic plate drives subduction in oceanic crust. As the slab is pulled down into the mantle, it drags the rest of the plate along with it, causing tectonic plate movement.
How does the density of a slab affect its movement according to slab pull theory?
-According to slab pull theory, a denser slab will sink faster than a less dense slab due to gravitational pull, and it will exert a greater force on the plate attached to it, thus affecting plate movement.
What is ridge push and how does it contribute to plate motion?
-Ridge push, or sliding plate force, is a force that occurs at mid-ocean ridges due to the rigid lithosphere sliding down the slope of the raised asthenosphere below. This gravity-driven mechanism results from the elevated position of the oceanic ridge, causing slabs of lithosphere to slide down the flux of the ridge.
What is the role of the asthenosphere in ridge push?
-The asthenosphere acts as a zone of soft, plastic material which is less dense than the riding plate above it, acting as a massive shear zone for the overriding plate, allowing the plate to slide down the slope of the asthenosphere due to the weight difference.
How does the difference in gravitational potential energy between a plate at its spreading center and subduction zone affect ridge push?
-The difference in gravitational potential energy between a plate at its spreading center and subduction zone causes the plate to slide down the slope of the asthenosphere, with the ridge push force increasing towards the subduction zone as the plate gets thicker and denser away from the spreading center.
What is the relationship between convection currents and the formation of seafloor spreading?
-Convection currents in the asthenosphere push magma up, forming new crusts, and exert a lateral force on the plate, which pushes it apart to create seafloor spreading.
Outlines
🌏 Plate Tectonics Forces: Convection Currents, Slab Pull, and Ridge Push
This week's discussion on plate tectonics delves into the forces behind plate movements, including convection currents, slab pull, and ridge push. Convection currents are likened to a conveyor belt, transferring heat within the Earth and creating loops of sinking hot rocks in the asthenosphere. This process is essential for plate tectonics, with Arthur Holmes proposing that mantle convection drives plate motion. Slab pull theory suggests that the weight of the plate itself, particularly during subduction, is a significant force in plate tectonics. Demonstrated through a simple paper clip chain model, slab pull is a strong force that can drag plates along with it. Lastly, ridge push, proposed by a geologist, is a force that occurs at mid-ocean ridges due to the lithosphere sliding down the elevated asthenosphere. This gravity-driven mechanism is influenced by the difference in gravitational potential energy between a plate at its spreading center and the subduction zone.
🌌 The Mechanics of Ridge Push in Plate Tectonics
The second lesson focuses on the ridge push mechanism in plate tectonics. This force is a result of the rigid lithosphere sliding down the elevated asthenosphere beneath mid-ocean ridges. The model suggests that the elevated position of the oceanic ridge causes lithospheric slabs to slide down, driven by gravity. The asthenosphere, being less dense and acting as a shear zone, allows the plate to slide down the slope due to the weight difference between the plate and its spreading center. As the plate moves away from the spreading center and towards the subduction zone, it thickens and becomes denser, increasing the ridge push force. This lesson concludes with a summary of the key points and a thank you to the viewers for their attention.
Mindmap
Keywords
💡Plate Tectonics
💡Convection Current
💡Slab Pull
💡Ridge Push
💡Asthenosphere
💡Conduction
💡Subduction
💡Mantle
💡Buoyancy
💡Seafloor Spreading
Highlights
Introduction to the seventh week of discussion on plate tectonics.
Focus on the possible causes of plate movements: slab pull, ridge push, and convection current.
Objectives: describe convection current, slab pull, and ridge push; explain what causes plate tectonics.
Convection current: a force that drives plate movement, similar to a conveyor belt.
Definition of convection current: a continuous loop of sinking hot, soft rocks in the asthenosphere.
Convection cell: a circular pattern that carries heat to the mantle's surface.
Convection in the mantle is essential for plate tectonics, behaving like convection in a pot on a stove.
Convection currents in the asthenosphere drive plate motion, as proposed by Arthur Holmes.
Slab pull theory: gravity and the plates themselves are responsible for plate tectonics through subduction.
Demonstration of slab pull using a paper clip chain to represent subducting tectonic plates.
Slab pull is a strong force that drives subducting tectonic plates due to the weight of the plate.
Slab pull theory suggests that mantle convection is a product of subduction, not the cause of plate tectonics.
Ridge push: a driving force for plate motion at mid-ocean ridges due to the sliding of the lithosphere.
Ridge push model proposed by a geologist, stating that the pushing on plates is due to gravitational potential energy differences.
The asthenosphere acts as a shear zone for the overriding plate, allowing it to slide down the slope of the ridge.
Ridge push force increases towards the subduction zone as the plate gets thicker and denser away from the spreading center.
Conclusion of the lesson, summarizing the three forces that cause plate tectonics.
Transcripts
hello great and
welcome to the seventh week of our
discussion on plate tectonics
now this week let's talk about the
possible causes of blade movements and
that includes the slab pool
the rich push and the convection current
at the end of the lesson you should be
able to one
describe convection current slab pull
and reach push and number two explain
what causes plate tectonics
there are three forces that interact to
create plate motion
we have the convection current the slab
pull theory
and the ridge push now let's explain how
each
force cause plate movement let's start
with
lesson one convection current
have you seen the apparatus where the
luggage of the travelers
are placed what do you call that device
[Music]
well that is a conveyor belt it is used
to transfer heavy objects from one point
to another
one of the forces that drives plate
movement works the same way the conveyor
belt does
and that is the conduction current now
what
is a convection current convection helps
to move
heat within the earth convection current
refers to the continuous loop of sinking
hot
soft rocks caused by energy transfer in
the asthenosphere
convection creates loops of sinking and
rising materials in the mantle
this circular pattern is called
convection cell
this carries heat to the surface of the
mantle much faster than hitting by
conduction
a convecting mantle is essential feature
of plate tectonics
convection in the mantle behaves the
same way convection happens in a pot
soap on a hot stove
the material near the heat source
becomes hot and expands
making it less dense than the materials
above
buoyancy causes it to rise and cooler
materials flow
in from the sides then sinks at the
bottom
creating cycles of the sinking of cold
and rising of warm water
this convection circling within the
mantle pushed the magma up
forming new crusts and exerting a
lateral force
on the plate pushing it apart to create
seafloor spreading
when colder magma sinks during
convection it pulls the surface together
making the denser crust to subduct
convection currents in the asthenosphere
drive plate motion
this theory of mental convection was
proposed
by arthur holmes according to him
as the mantle became heated its density
decreases and eventually rise and up
when the material cooled it would sink
exhibiting a circling behavior that
would look like a conveyor belt
the pressure heated magma broke the
continents apart
forcing the pieces to drift in opposite
directions
he also speculated that when the
material sink
continents will be brought back together
again
next is lesson 2 slab pool theory
slab pool theory states that gravity and
the plates themselves are the ones
responsible for the plate tectonics
through subduction process to clearly
explain how slab
pool works let's take a closer look at
this simple demonstration
in here the paper clip chain represents
abducting tectonic plates
now look closely as to what happens as
the chain moves
off the edge this simple demonstration
explains that slab pull is a strong
force that drives abducting tectonic
plates
the weight of the tectonic plate drives
subduction in oceanic crust
as the slob is pulled down into the
mantle it drags the rest of the plate
along with it
causing tectonic plate movement a very
dense slab will sink faster than
a less dense slot because of the
gravitational pull
and it will exert greater force on the
plate attached to it
slab pool theory believes that mantle
convection
is not the cause of plate tectonics but
rather
it is a product of subduction
now we have lesson 3 the ridge push
ridge push or sliding plate force is a
proposed driving force
for blade motion in plate tectonics this
occurs at mid ocean ridges
as the result of the rigid lithosphere
sliding down the hut
raised asthenosphere below mid ocean
ridges
this gravity-driven mechanism results
from the elevated position
of the oceanic ridge which causes slabs
of lithosphere to slide down the flux
of the ridge this gravity sliding ridge
push model was proposed by
bot a geologist which states that the
pushing on the plates
is actually due to difference in
gravitational potential energy
between a plate at its spreading center
and subduction zone
the asthenosphere is a zone of soft
plastic material which is less
dense than the riding plate above it it
acts as a massive
shear zone for the overriding plate
the plate will effectively slide down
the slope of the asthenosphere
due to the weight difference between the
plate and its spreading center
and the subduction zone since the plate
gets
thicker and denser the farther away from
the spreading center
the ridge push force will increase
towards the subduction zone
and that ends our lesson i hope you
learned something today
thank you for watching
thank you
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