PLATES.............................................

TOPIC
Processes that
Occur Along Plate
Boundaries
(Part 1)

REMEMBER!
Thinner oceanic crust
than continental crust
Oceanic crust is denser
that continental crust

Type of Plate Boundaries
CONVERGENCE of Different
Types of Crustal Plate
1. Oceanic – Continental Convergence
2. Oceanic – Oceanic Convergence
3. Continental – Continental Convergence

3 Types of Convergent Plate
Oceanic-Oceanic Convergence Oceanic-Continental Convergence
Continental-Continental Convergence

Oceanic-Continental Convergent Plate Boundary
Convergence between Oceanic Plate and
Continental Crust Plate

The leading edge of the
Oceanic Plate bends
towards the mantle since
it’s denser than the
continental Plate. The
bending of the denser plate
towards the mantle is
called subduction process.

Since the mantle is
hotter than the crust,
the tendency of the
subducted leading
edge of the oceanic
crust will be melted
forming magma.

Addition of volatile
material such as
water will cause
the magma to
become less
dense.

This allows the
magma to rise and
reach the edge of
the continental
crustal plate
forming volcanic
arc.

Aside from Volcanic
arc, what other
geologic events
could be formed in
convergence of
Oceanic-Continental
Crustal Plates?

The continups
grinding of plates
against each other
will cause the
occurrence of
Earthquakes.

One important
feature formed at
the oceanic crust
is a Trench, also
known as
Submarine
valleys.

Ocean
Trenches are
the deepest
part of the
ocean.

One of the deepest
trenches of the world is
the Philippine Trench
with a depth of 10, 540
meter.

Mariana Trench,
deep-sea trench in the floor of
the western North Pacific Ocean
, the deepest such trench
known on Earth, located mostly
east as well as south of the
Mariana Islands.

The Mariana Trench is
deeper than the Philippine
Trench. The Mariana Trench's
deepest point, Challenger
Deep, reaches a depth of
approximately 10,984 meters
(36,037 feet), making it the
deepest known point on

Oceanic-Oceanic Convergent Plate Boundary
Convergence between two Oceanic Plate
Crust Plate

A second type of
convergent plate
boundary involves
the sinking of
oceanic lithosphere
beneath another
plate of oceanic
lithosphere

Converging oceanic
plates will cause
formation of
Trenches, and these
trenches will become
sources of
earthquakes.

Underwater earthquakes, especially
the strong ones, can generate
Tsunami or Harbor Waves.

The leading edge of the subducted plate will eventually reach the mantle causing
it to melt and turn into magma. The molten material will rise to the surface
creating a Volcanic Island Arc Parallel to the trench.

Many parts of the Philippines originated from oceanic-oceanic
convergence. This resulted from the collision of two oceanic plates, with
one of the plates diving under the other.
OCEANIC CRUST
OCEANIC CRUST

Majority of the islands in the Philippines archipelago are considered as
part of the Philippine Mobile Belt. These islands were formed 65
million years ago at the southern edge of the Philippine Sea Plate and
are considered as part of island arcs.
OCEANIC CRUST
OCEANIC CRUST

The Philippine Mobile Belt is a complex zone in the Earth's crust
where several tectonic plates meet and interact. It runs through
most of the Philippine islands, which is why many islands in the
country are part of it.
OCEANIC CRUST
OCEANIC CRUST

Other parts of the Philippines, such as Palawan, Mindoro, and the
Zamboanga Peninsula are all highland sections of the Sundaland
Block of the Eurasian Plate.
OCEANIC CRUST
OCEANIC CRUST

Formation of the Philippine Archipelago
The Philippine Mobile Belt
eventually collided with
the Sundaland Block which
explains the presence of
trenches, such as the
Manila-Negros-Cotabato
Trench System, and the
Sulu Trench.
OCEANIC CRUST
MANILA
TRENCH
SULU TRENCH
SULU TRENCH
NEGROS TRENCH

On the eastern side of the
Philippines, trenches like
the Philippine Trench and
East Luzon Trough are
both products of
subducting Philippine Sea
Plate beneath the
archipelago.
OCEANIC CRUST
SULU TRENCH
SULU TRENCH
NEGROS TRENCH
EAST LUZON TROUGH

Aside from the formation
of trenches and troughs,
chains of active volcanoes
that stretches from Taiwan
to Mindoro were created.
Some known volcanoes in
this chain are Mt.
Pinatubo and Taal.
OCEANIC CRUST
EAST LUZON TROUGH

Also, the constant dipping
movement of slabs induces
frequent moderate to
strong earthquakes at
various depths, gives rise
to mountain ranges and
develops the geologic
character of the Philippine
Archipelago
OCEANIC CRUST
EAST LUZON TROUGH

Continental-Continental Convergent Plate Boundary
Convergence between two Continental Crust Plate

When two continental plate converge, a collision zone is formed.

Unlike the other two types of convergent boundaries, subduction ceases for
this type of convergence

What does it mean when we say “subduction ceases?

It means that no trench, no volcano and no island arc are created in
this type of convergwnt plate boundary.

Instead it leads to the formation of large group of tall mountains called
Mountain Range.

About 40 to 50 million years ago, two large land masses, India and
Eurasia, collided to begid the formation of the most visible product of
the Tectonics-the Himalayas.

Also, collision of continental plates is associated with
shallow earthquakeds activities

SUMMARY
There are three main types of
Convergent Plate Boundary;
1. Oceanic – Continental Convergence
2. Oceanic – Oceanic Convergence
3. Continental – Continental Convergence

SUMMARY
The Convergence of Oceanic and Continental Crustal
Plates can lead to the occurrence of Subduction Zone
that gives rise to the formation of Volcanic Mountain,
Earthquakes, and Trenches.

SUMMARY
Volcanic Mountains:
Formation:
When oceanic crust (which is
denser) collides with continental
crust, it is forced downward
(subducted) beneath the continental
crust. As the subducting plate
descends, it melts due to the heat
and pressure of the mantle,
generating magma that rises to the
surface, erupting and forming
volcanoes.
MAYON VOLCANO

SUMMARY
The Convergence of two Oceanic Crustal Plates can
lead to the occurrence of Subduction Zone that gives
rise to the formation of Volcanic Island Arc,
Earthquakes, and Trenches.

SUMMARY
If one of the leading edge of an oceanic plate suddenly
flicks upward, it can generate HARBOR WAVES or known
as TSUNAMI.

SUMMARY
Didicas Volcano:
This volcano, located in the
Babuyan Islands, was initially a
submarine volcano that breached
the surface in 1952. Before 1952,
it had erupted in 1857, and again
in 1900, leaving behind rock
masses. It is now a permanent
island with a lava dome and
crater.
DIDICAS VOLCANO

SUMMARY
Apolaki Caldera:
This massive caldera, located
within the Benham Rise (Philippine
Rise), is considered the largest in
the world with a diameter of 150
kilometers. It was discovered in
2019 by a team led by a Filipino
marine geophysicist. Despite its
size, it has been inactive for
millions of years.
DIDICAS ISLAND

SUMMARY
The convergence of Two Continental Crustal Plate differ
from the other two types of convergent plate boundary
because it ceases subduction zone, which means only
mountain ranges and shallow earthquakes are created.

TOPIC
Processes that
Occur Along Plate
Boundaries
(Part 2)

Divergent Plate Boundary
Different Types of Convergent Plate Boundary

Review/ Recall
Convergence of Oceanic and Continental Plate Boundaries

Review/ Recall
Formation of TRENCHES, VOLCANIC ARC, and EARTHQUAKES

Review/ Recall
Convergence of Two Oceanic Crustal Plate

Review/ Recall
Formation of TRENCHES, VOLCANIC ARCS and strong
EARTHQUAKES

Review/ Recall
Tsunami in Japan
2011

Review/ Recall
Convergence of Two Continental Plate Boundaries

Review/ Recall
No Subduction Zone, No Volcanoes, but due to the
Collision Zone it leads to the formation of MOUNTAIN
RANGES and shallow EARTHQUAKES.

DIVERGENT PLATE BOUNDARY
Divergent Plate Boundary is when the lithospheric plates
are moving apart from each other.

If the Divergent movement is happening on the oceanic
and continental plates

It can lead to the formation of an OCEANIC RIDGE
and RIFT VALLEY.

What are Oceanic Ridge and Rift Valley?
How are they form?

Oceanic Ridge
is an underwater
mountain range,
formed by plate
tectonics

The Oceanic Ridge occurs when convection currents rise in
the mantle beneath the oceanic crust and create magma
where two tectonic plates meet at a divergent boundary

As plates continue to move apart, an uplifted ocean floor will develop
in both sides of the plates which is called Ocean Ridge.

The Mid-Atlantic Ridge
is located along the floor
of the Atlantic Ocean,
and part of the longest
mountain range in the
world.

Rocks near the oceanic ridge are younger than
those far from it.

Age of the Earth’s Oceanic Crust
Rocks near the oceanic ridge are younger than
those far from it. MID-ATLANTIC RIDGE

Divergent Plate Movement can also occur in
Continental Plates

As continental plates
starts to move apart,
the crust will start
thinning and develops
a Continental Rift
Valley.

The Continental
Rift Valley will
develop into a
narrow sea, and
then into a wide
ocean.

Iceland is a country
located above the
Eurasian Plate and
North American
Plate that are
diverging from one
another.

The thingvellir(Þingvellir)
National Park is one of the
most frequently visited
attractions in Iceland.

TRANSFORM FALT PLATE BOUNDARY
If the blocks represent the lithospheric plates, you will
notice that there were two sets of divergent plate
boundaries – between blocks 1 and 2, and blocks 3 and 4

TRANSFORM FAULT PLATE BOUNDARY
But since the plates were adjacent to each other, a new
type of boundary is manifest and that is the transform
fault boundary (between blocks 2 and 3)

The presence of an
Oceanic Ridge is an
indication of Diverging
plates, and as the plates
diverge between the two
segments of the mid-
ocean ridge, the adjacent
slabs of crust are grinding
past each other forming
transform fault.

Transform boundaries
and the resulting faults
produced many
earthquakes because
edges of tectonic
plates are jagged
rather than smooth.

As the plates grind
past each other, the
jagged edge strike
each other, catch,
and stick, “locking”
the plates in place
for a time.

Because the plates are locked together without moving, a lot
of stress builds up at the fault line. This stress is released in
quick bursts when the plates suddenly slip into new positions.

The sudden movement is what we feel as the shaking and
trembling of an EARTHQUAKE

Most transform faults are located within
the ocean basins, there are few that cuts
through the continental crust like the

SUMMARY
Divergent Plate Boundary is when plates move apart
from each other forming Mid-Oceanic Ridge, Rift
Valleys, and Shallow Earthquakes

Transform Fault Plate Boundary is a fault along a plate
boundary where the motion is predominantly horizontal.

No leading edge is being destroyed, this means that NO Volcanoes,
NO Mountains are form but rather EARTHQUAKES

QUIZ

QUIZZ

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