Plate the plate are consumed, and areas where

Plate tectonics is a logical hypothesis that recognizes the
extensive scale movements of Earth’s lithosphere. Where plate’s boundaries
combine, the movement of these plates decides that what type of boundary form
here, Example convergence plate boundary, divergent plate margin, transforms margin.
With these plate margins, Quakes, volcanoes, mountain-building, and Marine
trenches are associated. The horizontal relative development of the plates
normally shifts from zero to 100 mm every year.

The Earth’s crust is divided into 12 plates which changes there
position in various directions with the passage of time. The motion of these
plates causes, collision (collide each other), Pull apart or slide past with
one another. With plate interaction different type of geologic structures or
tectonic feature are developed.

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Certain
theories of plate tectonic are present which explain that at ocean ridges the
plates are generated and along Subduction zones the plate are consumed, and
areas where transform fault present the plates are slide past each other and
when two plates collision occur, then suturing of plates occur.

Plate boundaries are classified into three types, on the
basis of motion relative toward one another.

a.      
Convergent plate boundary: One
plate plunges underneath another (Subduction) or two plates collide without
either subducting

b.     
Divergent plate boundary: New lithosphere forms as plates
pull apart.

c.      
Transform plate boundary: Plates grind past each other, no
change in Lithosphere.

These
three plate boundaries have different type of stresses so as this yield
different structure. At divergent plate boundary extensional stresses are produced
which make normal faults and graben which is uncommon. At transform plate
boundary shear stresses produced which causes bending and fractures in the rock,
fault, bending and uplift of rock occur. At convergent plate margin compressive
stresses are produced, because of which folds, reverse fault and thrust fault
are form.

At convergent plate boundaries collision of two plate occur
because of when two plates are moving towards each other. In these boundaries
the heavier (Denser) plate drive undergo the less heavy (lighter) plate. The
process at which one plate drive underneath the other is known as Subduction,
the plate which is going below the other are reach into the mantle and here
they melts because temperature is very high in the mantle.

At convergence plate boundaries continuously new Lithosphere
is produced occur along oceanic ridges, but there is no changing occur in the
earth total volume. The volume of earth remains same as previous one (earth
volume remain constant). There is a cyclic process continue, the older oceanic
lithosphere will go into the mantle as same rate as the rate of production of
sea floor.

Subduction zones which is also known as Convergent
boundaries. Subduction zones are the place where one plate is undergo beneath
the other (subducted) and will reach to the mantle. Subduction of two plates
occur when there is density contrast between the two plates for example the
oceanic lithosphere is subduct below the continental plates because oceanic
plates are denser than continental plate. The continental lithosphere is less
dense so there is no subduction occur and the oceanic plate will have high
density and will subduct up to greater depth.

When
the lithosphere having oceanic origin descend down and will go into mantle a
surface like feature are produced called deep ocean trenches, these trenches
are in the form of long and deep depressions. Example Pero Chile trench which
is 4499 km in length and 7.9 km below sea level present along the west coast of
S. America. Other example of western Pacific are Mariana trench and Tonga
trench which are deeper than those which are present in the Eastern Pacific.

The
oceanic plate slabs are goes down into the mantle with small angle or at 90
degree. The angle downward movement is depend upon the density of the plate.
For example when the spreading zone is around the subduction zone along Peru
Chile trench, the subducting material are younger and are hot and floating
outward. Here small angle of descent are form. Because of this the area around
the Peru Chile trench have large no of earthquakes i.e., 2010 Chile earthquake
which is also included in top 10 largest recorded earthquake. Properties of all
the convergent plate boundaries are same and they have very complex structures.
Each of these feature is form from different material and different tectonic
environment.

When
two ocean plate, or one continental and ocean plate or either two continental
plate meet or collide convergent boundaries are generated On the basis of this
there are three type of convergent plate boundaries.

1.     
Oceanic-continental
convergence

2.     
Oceanic-Oceanic
convergence

3.     
Continental-continental
convergence

This
is the type of convergence in which one continental plate and one oceanic
collide by one another. In the convergent the plate consuming higher density
(oceanic plate) goes down and reach into the mantle and the lesser density
plate (continental plate) floating. When these margins slabs reaches to the
mantle layer, they start melting of the block of asthenosphere, these processes
occur at a distance of 90-100 km..

In
that type of convergence partial melting of rock occur, which produced around
11 percent molten material then these melted substances are mixed with mantle
rock those which is not melted. When the oceanic plate goes downward, they
contain sediment which have high amount of water, these are derived from
oceanic crust, and the high pressure and temperature condition remove water
from the pore spaces. This process causes melting of rock which is called
partial melting. These melting rock are less dense than the surrounding rock
i.e. mantle rocks so these material rises upward in the form of volcanoes, but
all of these material not reaches to the surface and solidifies within the
earth crust which causes the increase in the crust volume.

Example
of the above process is Andes Mountain, which is form from the subduction of
Nazca plate below the South American plate, these are form from subduction of
oceanic lithosphere and known as continental volcanic arcs. Other examples
include the mountains of California contain Mount Rainer, Mount Shasta, and
Mount of St. Helens which is reach to the Canada and here it include Mount
Garibaldi, Mount Silverthorne and others.

When
two ocean plate are meet or collide each other, they form as oceanic-oceanic
convergence boundaries. Many feature which are produced along this type of
convergence are commonly present in continental plate boundaries. At this
boundary also subduction of one plate occur which reaches into the mantle and
triggers volcanic activity, as same process which is occur along
continental-oceanic convergence boundaries.

The
two ocean plate convergence setting, the volcanic activity generated from the
ocean floor. In this a chain of volcanic mountains are produced which is occur
in large amount and form as Islands. These are called as volcanic Island arc or
Island arc.

Example
Mariana and Tonga Islands (young island arc). The Island arc produced 99-301 km
from deep ocean trench. The western pacific ocean contain most island arcs, the
Atlantic Ocean contain only two island arcs. Antilles Island are form because
of the subduction of the Atlantic beneath the Caribbean plate, present in
United States, British virgin island and also present in Martinique island
example of this is Mount Pelee which is erupted in 1902 as well as kill 28,000
people.

The
island arc which is form newly have simple structure besides underlain by
oceanic crust, commonly less than 21 km thick. And the older island arc have
complex structures and are underlain by highly deformed crust which reaches to
36 km in thickness. Examples Japan, Indonesia, and Philippines. These island
arc are generated form early form island arc system.

 

This
type of convergent boundary is form from the collision of two continental
plates. In this type of boundary no subduction occur, because of this boundary
mountain ranges are form. When the collision of two continental plate occur it
will causes the formation of folds and deform the sediment and sedimentary rock
which is accumulate here along continental plate boundaries. This collision
causes the formation of high mountain ranges which is highly deformed and
contain sedimentary and metamorphic rocks.

Example
include the collision of indian plate and the Eurasisan plate, starts before
51-60 million years ago, produced Himalayas, which is the very important and
have the world most highest peaks. In this collision the crustal shortening
occur and increase in thickness takesplace.

Other
example include, Alps, Appalachians, and Urals which are also form as a result
of collision of two plates.

This report is about the convergent plate
boundaries, in which explain the formation of convergent plate boundary, how
subduction occur and how oceanic trenches are formed then explain the categories
of convergence plate boundaries,
Three distinctive types of convergent are recognized: (1) the convergence of
two oceanic plates, (2) the convergence of a continental plate and an oceanic
plate, and (3) the convergence of two continental plates.

Convergent
plate boundaries (continental-continental) is a place where two tectonic plates
meet each other. All tectonic plates are constantly being moved because of the
convection currents that occur in the mantle. Continental plates are creating
mountains when they pushed into each other. A few examples of this feature are
the Himalaya Mountain Range and the Appalachian Mountain Range.

A
subduction zone also develops where oceanic and continental plates converge.
The less-dense continental crust always resists subduction into the dense
mantle and over rides the oceanic plate. Consequently, the volcanic arc forms
on the continent, and compression may deform the continental margin into a
folded mountain belt.

The
simplest type of convergent plate boundary is ocean-ocean convergence which consists
of two oceanic plates. As the plates collide, one is thrust under the other
forming a subduction zone. The subducting plate run down to the mantle, where
it is heated, starting the generation of magma. The magma, being less dense
than the neighboring rocks, upsurges and blowup on the seafloor, ultimately
building an arc of volcanic islands. Andesite is the volcanic rock that
characteristically forms at such sites.