This is the summary on gateway 1 on plate tectonic. It discusses about the following: 1) Characteristics of the different structure of the earth. 2) The mechanism leading to plate movement 3) Landforms associated to the different plate movement.

1. Revision on
Plate Tectonic

2. b. What is the internal structure of the earth?

3. Characteristics of the
different earth structures
Crust Mantle Core
Temperature Nil 800-3000°C 3000-
5000°C
Thickness About 70 km 2900km 3000 km
Types of
materials
Basalt (Oceanic: 5-
8km) & Granite
(Continental crust-
30-60km but less
dense)
Solid rocks Iron and
Nickel
Summary- It is thicker and hotter as it moves from the crust to the core.

4. Why do tectonic plate
moves?
• Convection current
• Slab pull force

5. Why do tectonic plate
moves?
• Tectonic plates float on molten mantle, driven by
convection currents. As the molten mantle materials
is heated by the core, mantle expands, rises and
spreads out, dragging the plates away from each
other.
•Subsequently, the hot molten mantle cools slightly
and sinks, pulling the plates along. Hence plates
move towards each other.
•The sinking mantle material heats up again as it nears
the core and the whole process repeats.

7. 2. Slab-pull force
• Subduction occurs with the difference in
density. An oceanic plate (denser) subducts
under a less dense plate and pulls the rest of
the plate along.
• The subducting plate drives the downward-
moving of the crust.
d. Why do tectonic plates move?

8. Oceanic-Oceanic
diverging
• When two oceanic plates diverge, fractures are
formed at the plate boundary.
• Magma rises from the mantle to fill the gap
between the plates.
• New sea floor is formed when the magma cools
and solidifies.
• Magma rises at the zone of divergence to form the
mid-oceanic ridge.
• At various points along the ridge, magma builds up
above the ocean to form volcanic islands.

9. Continental-continental
diverging
• When continental plates diverge, they are
stretched, causing fractures to form at plate
boundary.
• Land in between 2 continental crusts sinks, forming
a depression known as rift valley.
*When the crusts on either side of the normal faults move
apart, they sink and leave the central block standing higher
than the rest, thus forming a block mountain.

10. 3.Oceanic-continental plate convergence
• When an oceanic plate meets a continental
plate, the denser oceanic plate subducts
under the less dense continental plate.
• A subduction zone forms, creating a deep
oceanic trench along the plate boundary.
• The subduction of the continental plate
causes the soild mantle material to melt and
magma is formed.
e. What are the different types of plate
boundaries?

11. 1. Oceanic–oceanic plate
convergence
• When two oceanic plates converge, one subducts
under the other.
• A subduction zone forms, creating a deep oceanic
trench.
• The subduction of the oceanic plate causes the
solid mantle material to melt and magma is formed.
• The magma rises through the mantle and ocean
floor to emerge as volcanoes.
• Eventually a chain or arc of islands called island arc
is formed.

12. Continental
crust
Continental
crust

13. 2. Continental-continental
plate convergence
• However, both plates have similar densities and
hence, resist subduction.
• As a resist of the compressional force put against
both plates, the plates break, slide along fractures
in the crust, buckle and fold, forming fold
mountains.
• E.g. the Himalayas - convergence of the Indian
Plate and the Eurasian Plate.

15. • When oceanic and continental converge, oceanic
plate subducts under the continental.
• A subduction zone forms, creating a deep oceanic
trench.
• The subduction of the oceanic plate causes the solid
mantle material to melt and magma is formed.
• The magma rises through the mantle and ocean floor to
emerge as volcanoes.
• The edge of thick continental plate buckles to form fold
mountains.
• Earthquakes may also occur.
• E.g. the Australian Plate subducting under a section of
the Eurasian Plate near Sumatra formed the Sunda
Trench.
3.Oceanic-continental plate convergence
e. What are the different types of plate
boundaries?

16. Transform plate boundaries
• Plates slide past each other.
• As they do so, tremendous stress builds up.
• This stress is eventually released, often as a
violent earthquake.
• E.g. San Andreas Fault, United States of
America & North Anatolian Fault, Turkey
e. What are the different types of plate
boundaries?

17. Transform plate boundaries
• Plates slide past each other.
• As they do so, tremendous stress builds up.
• This stress is eventually released, often as a
violent earthquake.
• E.g. San Andreas Fault, United States of
America & North Anatolian Fault, Turkey
e. What are the different types of plate
boundaries?