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As compared to the rocks that makeup the crust, earth as a whole is a rock nighjhaaaaaaaaa
Answer:
Density is one of the most factors that play a key role in plate tectonic activities. Some of the ways in which density is important in the field of plate tectonics are as follows-
- The convergent plate boundaries are responsible for the creation of a subduction zone, where the high-density lithospheric plate subducts below the less dense one. It is because the heavier plate is comprised of heavy minerals thereby forming heavier rocks as a result of which its density increases. Due to these differences in density, there occurs a subduction zone.
- The divergent plate boundary forms where two plates move away from one another. This type of plate motion is responsible for the eruption of magma on the seafloor. As the plates diverge, the lithosphere becomes eventually thin, and with more progressive spreading, the magma comes out to the seafloor. This is because the hot magma is less dense, and forms convection cells as they rise upward. This is how the density helps in the upwelling of magma at the mid-oceanic ridge in a divergent plate boundary.
- When there collide two plates of equal densities, then it gives rise to the formation of huge mountains, because neither of them is heavy to get sink. So it uplifts the crust, forming a sandwich-type pattern.
The main reason why the tectonic plates move is the conversational currents. There is magma between the upper mantle and the asthenosphere that heats up at the upper mantle. The weight is so small that the magma rises with the help of these conversational currents. When the magma has ascended towards the asthenosphere, it has nowhere to go so the magma lies along the asthenosphere. There the magma cools down again because the asthenosphere is colder than the upper mantle, which makes the magma heavier and goes back down to the upper mantle, where the magma heats up again and everything starts all over again and so it goes on over and over again. Scientists have concluded that the earth's gravity causes two other processes that also cause the tectonic plates to move.
Ridge push - in the spreading zones, the sides of the tiles are raised and slide to the side as in a slide.
Slab pull - when a plate is pulled down by gravity in a subduction zone like an anchor.
