How does magma from Earth’s mantle reach an oceanic ridge?

Magma reaches an oceanic ridge primarily through the process of seafloor spreading at divergent plate boundaries. As tectonic plates move apart, the underlying mantle rock—typically peridotite—rises toward the surface due to mantle convection.312

This upward movement causes a decrease in pressure on the mantle rock. Because the mantle is already at temperatures near its melting point, this reduction in pressure triggers partial melting, creating buoyant basaltic magma. This molten material then wells up through faults and fractures created by the divergent forces, eventually cooling near the surface to form new oceanic crust. The elevated topography of the ridge, sustained by this upwelling heat, further facilitates the process by allowing gravitational forces to push the plates apart, creating space for more magma to rise from below.32145