TENSION ZONE
As plates move apart, a tension zone is formed. Which between magma and water, rises to the tension zone?
When plates move apart at divergent boundaries, magma rises to the tension zone, not water. This is due to the process of decompression melting that occurs as the pressure on the mantle rock decreases with the upward movement of the plates.
As the plates separate, the asthenosphere underneath is exposed to lower pressure, causing it to partially melt and form magma. This magma is less dense than the surrounding solid rock, so it rises through the tension zone created by the separating plates.
In contrast, water does not typically rise to these zones because it cannot penetrate deep into the mantle and does not undergo the same phase changes as rock under decompression. Therefore, it is magma that rises to the tension zone, where it solidifies and creates new crust.
