Processes at plate margins (Converging plate margins) Flashcards
What happens where two oceanic plates converge
Where two oceanic plates converge, the colder, denser plate will subduct beneath the other, forming an oceanic trench.
What happens to the subducted plate
The subducted plate is heated and melts around 100km below the surface
What is an island arc and provide an example
Some molten may rise through lines of weakness to the surface, resulting in a curved chain of volcanic islands called an island arc (The Tonga islands by the Tonga trench)
What are converging plate margins
Converging plate margins are also known as destructive plate boundaries
What are subduction zones
The subduction zone is the place at a converging plate margin where one plate descends below the other
What occurs at oceanic and continental plate margins
Where oceanic and continental crusts converge the denser oceanic crust is subducted by slab pull
The less dense continental crust gets buckled and folded, to form mountain chains
How do volcanoes form at oceanic and continental plate margins
The oceanic plate (one that subducts) melts forming a magma chamber, magma then rises through weak points in the continental crust to form volcanoes
What is the Benioff zone
The interaction of the two plates in the subduction zone creates earthquake activity up to 700m deep in an area called the Benioff zone
What happens where two continental plates converge
When two continental plate margins converge their similar densities result in no subduction, however the plates edges and sediment trapped between the plates are forced up creating force mountains, such as The Himalayas
What volcanic activity occurs at continental plate margins
Because there is no subduction no volcanoes can occur but their is a potential for earthquake activity
