Final answer:
Mantle plumes are hot areas in the mantle that rise to create volcanoes and volcanic islands in the oceanic lithosphere. Hotspots result from these plumes and can cause significant volcanic activity. They are crucial for understanding tectonic movements and geological processes.
Step-by-step explanation:
Mantle plumes are regions where hot material from deeper within the Earth's mantle rises towards the surface. This upwelling of heat can lead to the formation of volcanoes and other geological features. When mantle plumes occur beneath the oceanic lithosphere, they often create volcanic islands as the hot material melts the earth’s crust, producing mafic magma that can lead to basalt lava flows.
Hotspots and their related volcanism are important because they provide information about the movements of tectonic plates and the processes occurring within the Earth’s mantle. As plates move across hotspots, the resulting chain of volcanoes can track plate motion over geological time, creating a record of how the Earth's surface has changed.