Final answer:
Decompression melting is the process where ascending mantle rocks melt due to a decrease in pressure. It commonly occurs at mid-ocean ridges and hotspots where tectonic plates move apart or hot mantle plumes rise.
Step-by-step explanation:
What is Decompression Melting?
Decompression melting is a geologic process where the melting of mantle rocks occurs due to a decrease in pressure, without an increase in temperature. As rocks from the Earth's mantle ascend, the pressure decreases, which lowers their melting point and causes them to melt. This process often happens near tectonic plate boundaries, especially at mid-ocean ridges, where the tectonic plates are moving apart. It can also occur at hotspots, where a plume of hot mantle rises towards the surface.
Where Does Decompression Melting Occur?
Mid-ocean ridges are the most common areas where decompression melting is observed. This happens because the divergent movement of tectonic plates decreases the pressure on mantle rock, inducing melting and leading to the creation of new oceanic crust. Hotspots, which are not associated with any particular plate boundary, can also be zones of decompression melting due to rising mantle plumes.