Convergence and collision zones/plates

Convergence zone

• Are also know as destructive plates (zones) or the zone of subduction.
• This is when two plates move towards each other as shown on the diagram above.
• An Ocean crust moves towards a continental crust but being heavier,
• It (the oceanic crust) sinks (is subdued by the continental crust hence the name zone of subduction) and is destroyed into the mantle forming deep-sea trenches and
• Island arcs with volcanoes.
• Since one plate (the oceanic plate) and sediments are being destroyed the zone is termed the destructive zone.
• Thus when two plates move towards each other, their leading edges are destroyed as they collided and push one another.
• For example the Nazca plate (near Peru South America) an oceanic plate sinks under the South American plate (the Andes)
• The Juan de Fuca sinks under the North American plate (Rockies) forming the Island arc of the West Indies.

Collision zone

Collision zone. Image Classromatsea

• This is when two continental crust collide and as neither can sink
• they are formed into fold mountains.
• For example the India Plate collided with Eurasian Plate forming the Himalayas
• The African Plate collided with the Eurasian Plate forming the Alps.

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