Discuss three (3 ) mechanisms of magma origination

Answer 1

Spreading ridges: Beneath spreading ridges, the temperature locally exceeds the melting temperature, at least in part because pressure decreases. That is, plate separation at ridges probably causes a decrease in pressure on the already hot rocks at depth, thus initiating melting.

Subduction zones: When an oceanic plate is subducted beneath either a continental plate or another oceanic plate, a belt of volcanoes and plutons is found near the leading edge of the overriding plate. As a subducted plate descends toward the asthenosphere, it eventually reaches a depth at which the temperature is high enough to initiate partial melting.

Hot Spots: A hot spot is an area over which a plate moves, thereby yielding a succession of volcanoes. Hot spot volcanism results from a rising mantle plume, a cylindrical plume of hot mantle rock that rises from perhaps near the core mantle boundary. As it rises toward the surface, the pressure decreases on the hot rock and melting begins, thus yielding magma.