Processes along Plate Boundaries

Processes along Plate Boundaries

By: JOESEL DARIAGAN LPT, MS

Learning competency

Explain the different processes that occur along the plate boundaries

Open Ended

How Do Tectonic Plates Move?

process Along Plate Boundaries

Geomorphology is the scientific study of landforms and the processes that shape them.

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Nijima

On November 21, 2013, a new island dubbed as Nijima was born after an undersea volcanic eruption at the surface of the Pacific Ocean about 600 miles south of Tokyo, Japan.

Processes Along Convergent Plate Boundaries

When continental and oceanic plates collide, the thinner and denser oceanic plate is overridden by the thicker and less dense continental plate. The oceanic plate is forced down into the mantle in a process known as "subduction." As the oceanic plate descends, it is forced into higher-temperature environments. At a depth of about 100 miles (160 km), materials in the subducting plate begin to approach their melting temperatures and a process of partial melting begins.

​ https://geology.com/nsta/convergent-boundary-oceanic-continental.gif

Open Ended

What process if the denser oceanic plate moves under the continental plate?

Fill in the Blanks

Processes Along Convergent Plate Boundaries

When a convergent boundary occurs between two oceanic plates, one of those plates will subduct beneath the other. Normally the older plate will subduct because of its higher density. The subducting plate is heated as it is forced deeper into the mantle, and at a depth of about 100 miles (150 km) the plate begins to melt. Magma chambers are produced as a result of this melting, and the magma is lower in density than the surrounding rock material. It begins ascending by melting and fracturing its way through the overlying rock material. Magma chambers that reach the surface break through to form a volcanic eruption cone. With continued development the islands grow larger, merge, and an elongate landmass is created.

​ https://geology.com/nsta/convergent-boundary-oceanic-oceanic.gif

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Processes Along Convergent Plate Boundaries

In this type of convergent boundary, a powerful collision occurs. The two thick continental plates collide, and both of them have a density that is much lower than the mantle, which prevents subduction (there may be a small amount of subduction, or the heavier lithosphere below the continental crust might break free from the crust and subduct). Fragments of crust or continent margin sediments might be caught in the collision zone between the continents, forming a highly deformed mélange of rock. The intense compression can also cause extensive folding and faulting of rocks within the two colliding plates.

​ https://geology.com/nsta/convergent-boundary.gif

Open Ended

Mountain ranges are formed from continental-continental convergence. Give an example of mountain range

Processes Along Convergent Plate Boundaries

CONVERGENT = DESTRUCTIVE

SUBDUCTION- the process by which two plates collide and one plate is drawn underneath the other.

Multiple Choice

What geologic features resulted from the collision of the two continental plates?

• volcanic island arc

• fault

• mountain

• earthquake epicenter

Multiple Choice

Which of the following is the result of the collision of two oceanic plates?

• TRENCH

• RIFT VALLEY

• VOLCANO

• FAULT LINE

Multiple Choice

Why does the oceanic crust sink beneath the continental crust at the subduction zone?

• The oceanic crust has a greater density.

• The oceanic crust is pulled downward by Earth’s magnetic field.

• The oceanic crust is pushed from the ridge.

• The continental crust has a denser composition.

Multiple Choice

When a convergent boundary occurs between two oceanic plates, what will happen to one of those plates?

• The plate will subduct beneath to the other plate.

• The plate will subduct toward to the other plate.

• The plate will move away to the other plate.

• The plate will move toward to the other plate.

Processes Along Divergent Plate Boundaries

DIVERGENT = CONSTRUCTIVE

Divergent plates separate and new crust is formed to fill in the gap left by the two divergent plates.

Processes Along Divergent Plate Boundaries

When a divergent boundary occurs beneath oceanic lithosphere, the rising convection current below lifts the lithosphere, producing a mid-ocean ridge. Extensional forces stretch the lithosphere and produce a deep fissure. When the fissure opens, pressure is reduced on the super-heated mantle material below. It responds by melting, and the new magma flows into the fissure. The magma then solidifies and the process repeats itself.

​https://geology.com/nsta/divergent-boundary-oceanic.gif

Processes Along Divergent Plate Boundaries

Divergent plates separate and new crust is formed to fill in the gap left by the two divergent plates.

​https://geology.com/nsta/divergent-boundary-oceanic.gif

Processes Along Transform Plate Boundaries

Transform Plate Boundaries are locations where two plates slide past one another. The fracture zone that forms a transform plate boundary is known as a transform fault. Most transform faults are found in the ocean basin and connect offsets in the mid-ocean ridges. A smaller number connect mid-ocean ridges and subduction zones.

Processes Along Transform Plate Boundaries

TRANSFORM = CONSERVATIVE

​Transform Plates move past one another, sliding. They do not destroy or create land.

Multiple Choice

What geologic feature forms when a divergent boundary occurs beneath the oceanic lithosphere and there is a rising convection current below lifts the lithosphere?

• mountain belts

• volcanic arcs

• mid-ocean ridge

• afault line

Multiple Choice

Which of the following geologic features formed in the divergent plate boundary?

• San Andreas fault

• Mt. Himalayas

• Sierra Madre 

• Great Rift Valley of East Africa

Multiple Choice

What topographic feature is formed in the divergent boundary?

• fault 

• mountain

• rift valley

• volcano

Multiple Choice

Which of the following can we expect to find at a mid-ocean ridge?

• relatively young rocks

• very ancient rocks

• reverse fault

• the thick accumulation of sediments

Open Ended

Among the three plate boundaries, what is the most dangerous plates when they move?