Question

How do convergent and divergent plate boundaries cause magma formation?

Answer 1

Hint: Magma forms in a variety of ways due to differences in temperature, strain, and structural formations in the mantle and crust. The upward displacement of Earth's mostly-solid mantle is referred to as decompression melting. Decompression, or a decrease in overlying pressure, allows the mantle rock to melt and form magma.

Complete answer:
The crust and upper mantle of the Earth's lithosphere are made up of a collection of parts called tectonic plates that shift slowly over time.

Divergent plate boundary -
When two tectonic plates shift away from each other, they form a divergent boundary. Earthquakes are natural around these margins, and magma (molten rock) rises to the surface from the Earth's mantle, solidifying to form a new oceanic crust. Divergent plate boundaries include the Mid-Atlantic Ridge and the Pacific Ring of Fire.

Divergent plates, such as those found along the mid-Atlantic ridge, are areas where two ocean plates break and pull apart. The separation creates a crack that allows liquid rocks to escape. The magma typically forms basalt, which is a heavy rock. Fresh islands rise to the surface in areas like Iceland as magma presses up from the mantle.

Decompression, or a decrease in overlying pressure, allows the mantle rock to melt and form magma. At divergent boundaries, where tectonic plates break, decompression melting is common. Because of the rifting movement, the buoyant magma underneath rises and fills the lower-pressure vacuum.

Convergent Plate boundary -
A convergent boundary is formed when two plates come together. The collision of the plates may cause one or both plates' edges to buckle up into mountain ranges, or one of the plates to bend down into a deep seafloor trench. Parallel to convergent plate boundaries, a chain of volcanoes sometimes forms, and powerful earthquakes are common along these boundaries.

Oceanic crust is often pulled down into the mantle at convergent plate boundaries, where it starts to melt. Magma rises through and through the other plate, solidifying into granite, the continent-forming rock. As a result, continental crust is formed and oceanic crust is destroyed at convergent boundaries.
Magma is produced at convergent boundaries when water from a subducting plate acts as a flux, lowering the melting temperature of the nearby mantle rock. Magma forms at divergent boundaries due to decompression melting. Inside a mantle plume, decompression melting also occurs.

Note: A transform plate boundary is formed by two plates sliding past each other. The San Andreas fault zone, which stretches underwater, is home to one of the most well-known transform plate boundaries. Structures that cross a transform boundary, whether natural or man-made, are offset—split into pieces and carried in opposite directions. When the plates grind along, the rocks along the border are pulverised, forming a fault valley or undersea canyon. Along these faults, earthquakes are common. Crust is cracked and broken at transform edges, but not formed or killed, unlike convergent and divergent boundaries.

The mid-Atlantic ridge, where the Eurasian Plate, which occupies all of Europe, divides from the North American Plate, is an example of a divergent boundary. As new crust forms, this underwater mountain range continues to expand.