Final answer:
Water enables plate tectonics by lubricating subducting plates, introducing water into the mantle to lower the melting point of rocks and generate magma, and aiding in the cycling of materials through weathering and sediment transport.
Step-by-step explanation:
Water plays several vital roles in enabling plate tectonics to operate on Earth. One of the key processes powered by water is the lubrication of subducting plates, where oceanic crust bearing water-rich minerals descends beneath other plates.
As these hydrated minerals are subjected to increasing pressure and temperature, they release water into the surrounding mantle.
This addition of water lowers the melting point of the mantle rocks, aiding in the generation of magma at convergent plate boundaries.
Moreover, water as a weathering agent contributes significantly to the breakdown of rocks on Earth's surface, facilitating the transport of sediments to different locations where they can be subducted along with the tectonic plates. This process further introduces water into the mantle, perpetuating the cycle of magma generation.
The role of water in the mantle's convection system, which drives the movement of plates, is analogous to that in boiling water, where warmer, less dense material rises, and cooler, denser material sinks, enabling the transfer of heat and material.