Mantle convection Flashcards
Slab pull and ridge push
What mechanism is mantle convection?
A mechanism that transfers heat from the Earth’s hot interior to the cooler surface.
What trigger plate movement?
Gravity
Why does mantle plume rises and thrusts itself into the lithosphere?
Rock in lower mantle is intensely heated by the core. Then, mantle rock is heated, it expands and become less dense, hence it rises and thrusts itself into the lithosphere above.
Carrying on the above, how is magma produced?
The oceanic lithosphere(100-200km) is undergone thinning. The melting point of the rocks(in the asthenosphere) is lowered as the pressure decrease, thus magma is produced.
How is the “ridge” in the term “ridge push” formed? (NOT A DSE TYPE QUESTION)
How magma rises and fills the fissures to form new crustal materials, which is hot and less dense crustal materials then the existing crust. It thus rises and form an upswelling ridge.
How does the “push” in the term “ridge push” occur? (NOT A DSE TYPE QUESTION)
The new oceanic lithosphere is formed when the upswelling ridge cools and solidifies. It then cools and contracts, becoming denser and thus slide down from the two sides of the ridge due to gravity.
The sliding is an indication of TENSIONAL force. Two plates move apart from each other.
How do the oceanic lithosphere changes when it become older?
It merges with other rock materials in the asthenosphere–> thicker(1)
It forms a dense, heavy slab of plate after millions of years.(1)
Carrying on the above, How does slab pull occur? What is the result of slab pull on two plates?
The heavy, dense slab of plate collides with other plates.(1) It subduct into the asthenosphere, creating a suction force,(1)which pulls the rest of the plate behind it(1)
Under compressional force(1), two plates collide(1)
