Processes within plate boundaries? Flashcards
Mantle convection
Heat produced by the decay of radioactive elements in the Earth’s core heats the lower mantle – creating convection currents which cause the plates to move.
Slab pul
Newly formed oceanic crust at mid ocean ridges becomes thicker and denser as it cools. This causes it to sink into the mantle under its own weight – pulling the rest of the plate down with it.
Subduction
as two plates move towards each other, one slides under another into the mantle – where it melts in an area known as the subduction zone.
Seafloor spreading
in the middle of many oceans hot magma is forced up from the asthenosphere and hardens forming new oceanic crust. This new crust pushes the tectonic plates apart
Two divergent landforms
Mid ocean ridges - Plates underwater, e.g mid atlantic ridge
Rift valleys - Plates above land, form fault lines, volcanoes e.g Kilimanjaro
What occurs at divergent (Constructive) boundaries
Formation of new oceanic crust as magma rises to the surface and solidifies.
Widening of the oceanic plate.
Formation of oceanic ridge and rift valley.
What occurs at Convergent (Destructive) boundaries
Subduction of one plate beneath another.
Formation of deep oceanic trenches.
Generation of earthquakes and volcanic activity.
Melting of subducted plate creates magma, leading to formation of island arcs and volcanic mountain ranges.
What occurs at Transform (Conservative) boundaries
Two plates sliding past each other in opposite directions.
Creation of strike-slip faults such as the San Andreas fault in California.
Earthquakes and ground deformation along the fault.
What can happen when plates collide
Collision between two plates can result in the formation of a continent-continent or continent-oceanic plate boundary.
Large-scale deformation and uplift of the earth’s crust.
Formation of mountains, such as the Himalayas.
What are subduction zones how do they occur
A subduction zone occurs where an oceanic plate sinks beneath a continental plate.
Melting of the subducted plate creates magma, which rises to the surface and solidifies, forming a volcanic arc.
Generation of earthquakes and volcanic activity.
what are hotspots
A fixed area on the Earth’s surface where magma rises from the mantle and forms volcanic activity.
Not associated with plate boundaries.
Examples include Hawaii and the Yellowstone Caldera.
what are oceanic ridges
A long mountain range on the ocean floor formed by the upwelling of magma at divergent plate boundaries.
Characterized by shallow earthquakes and volcanic activity.
