Final answer:
The asthenosphere is the semi-fluid zone where hot, partly melted rock can be deformed by heat and pressure, allowing for the movement of tectonic plates. This is facilitated by mechanisms such as introduction of water at subduction zones and increased temperature at mantle plumes.
Step-by-step explanation:
The zone with hot, partly melted rock which can be deformed by heat and pressure to allow plate movement is known as the asthenosphere. This region exists beneath the rigid outer layer known as the lithosphere and is involved in tectonic plate movements. The asthenosphere is composed of a semi-fluid peridotite which is hot enough to flow slowly, and this flow is facilitated by the decrease in melting temperature caused by water introduced through subduction zones, as well as increased temperatures in hotspot regions where mantle plumes rise towards the surface.
The asthenosphere is crucial in the process of convection in the mantle, where heat is transferred upwards and cooler material sinks, allowing the tectonic plates above to move. This movement can lead to various geological phenomena such as earthquakes, volcanic activity, and the formation of rifts, subduction zones, and mountain ranges. The dynamic nature of the Earth's crust is a result of the complex interactions within these zones of the Earth's interior.