Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 1.1 & 1.4 (plate tectonic) - Coggle Diagram
Chapter 1.1 & 1.4 (plate tectonic)
Types of plate boundaries
1.
Divergent boundary
(plates moving away from one another)
Types of it for divergent
oceanic-oceanic plate boundary (North-America and Eurasian plate boundary)
continental-continental plate boundary (Nubian and Somalian plate)
Oceanic-oceanic plate boundary
Mid-ocean ridge [long, linear elevated on the ocean floor]
centre of the ridge: riff valley (deep with steep sides)
2 plates will
move apart
by
convection current
that experience tensional force, which cause fractures to form plate boundary
decrease in overlying pressure
cause parts of the
underlying mantle to melt
, forming
magma
These magma will
escape the fractures
and
rise
through the
weak areas of the crust
to the seafloor to
fill the gaps
caused by the spreading plates to form new crusts
The lava will
cool and solidify
to
make up
oceanic crust, forming
mid-oceanic ridge
Magma continues to
escape the cracks
, which will
build up and solidify
into
undersea volcano
and when it rise above sea level, it forms volcano
after many eruptions, it
breaks the ocean surface
to form
islands
earthquakes
occurs in this area as
stress released when plates diverge
Examples:
Iceland is located at the Mid-Atlantic Ridge between the divergent boundary between Eurasian and North American plates
an upsurge of abnormally hot rocks and movements of magma chambers caused hotspot or mantle plate
c-c plate boundary
Riff valley (linear depression with steep sides)
Two continental plate
pulled apart
by convection current that experiences tensional force
The rock fractures to form parallel faults
Over time, the centre land block will sink between 2 parallel faults, forming riff valley
Follow 2nd step of o-o divergent. \Magma rises through weak areas in the crust to the Earth's surface, forming volcanoes
Follow last step of o-o divergent
Example:
Nubian and Somalian Plate pulling apart, forming Great Riff Valley
Volcanoes found there are Mount Kenya and Kilimanjaro
Convergent boundary (plates moving towards one another)
o-o plate boundary
Oceanic Trench
(deep depression in the subduction zone)
Two oceanic plate will move towards one another
The
denser
oceanic crust will
subducts under
the
less dense
oceanic crust
A
subduction zone
is formed, creating oceanic trench
Island Arc
The
subducted oceanic plate
cause a
high pressure forces to water out
of its oceanic crust
The water
lowers the melting point of the overlying mantle
, which will melt to form magma
Magma
will
rise
through the crust to form
volcano
(some remain underwater [submarine volcano]) and
a chain of islands
will form a
volcanic island arc
Example: Pacific plate subducting beneath the Philippine Plate, forming the Mariana Trench and Mariana Island
c-c plate boundary
Fold Mountains
Since both convergent plates have
similar densities
, when two move towards each other, they
resist subduction
Compression force
continues to
build
, the plates can
break
,
slide
along the
fractures
and
fold
, rocks will be
uplifted and buckled through pressure
, forming fold mountains
Earthquakes
there can be
violent
due to the
build-up pressure
Example: Continental Indian Plate converge with continental Eurasian plate, forming Himalaya mountain range
The Mount Everest area experience many earthquakes, like the earthquake that struck Nepal in 2015
o-c plate boundary
Oceanic Trench
The denser oceanic plate will subduct under the less dense continental plate as it converge
A subduction zone will be formed, creating an oceanic trench
Volcano
The subducting oceanic plate sinks into the mantle, causing high pressure forces the water out of the oceanic crust
Water lower the melting point of the overlying mantle, which will melt and forms magma
magma rises through the crust to form volcano
Fold Mountain
edge of thick continental plate will break, slide over fractures and fold, forming fold mountains
Example: Oceanic Nazca Plate subducts beneath the continental South America Plate, forming Peru-Chile Trench, Andes fold mountain range and Nevado de Ruiz volcano
Transform boundary (plates sliding past each other)
Faults
Two plates try to
slide past each other
Friction
causes
2 plates
to
get locked
and
stress builds up
3.
Stress
will produce
a fault
, which is the fracture zone
Earthquake
When one plate
suddenly slips past another
, it causes earthquake
no magma rising to the Earth's surface, so no volcano
Example: Pacific Plate sliding past the North America Plate, forming San Andreas Fault in California, USA and Loma Prieta earthquake in California
Factors contributing to plate movement
Convection current
Divergent movement
Heat from earth's core
cause
mantle material
to be
less dense
The
mantle material
will
rise
to the
surface
the
rising convection current
will
spread beneath the plate
and
drag it away
, leading to
divergent movement
Convergent movement
The
mantle materials
will
lose heat and sink
down towards
the core
convection current collide
with one another, leading the
convergent movement
Heat
from core will heat up the
mantle materials again
, and the
process repeats
again
rising and sinking
of mantle materials leads to
convection current
Slab-pull force
denser oceanic crust pulled down by gravity
as it
subducts beneath
the
less dense crust
, leading to
convergent movement
denser oceanic crust
will
sink deeper into the mantle materials
by its own weight,
pulling the rest of the plate with it
, leading to
further convergence