Question

Which statements accurately describe the aspects of plate tectonics that involve subduction and seafloor spreading? Check all that apply. HELP

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1.)Older crust is melted at subduction zones.

2.)Oceanic crust is created at mid-ocean ridges.

3.)Crust is created at the coastlines of continents.

4.)Continents move due to seafloor spreading and subduction.

5.)Crust is created as the mantle hardens under the lithosphere.

Answer 1

1. Older crust is melted at subduction zones.

2. Oceanic crust is created at mid-ocean ridges.

4. Continents move due to seafloor spreading and subduction.

Answer 2

The correct answers are:

1.) Older crust is melted at subduction zones;

2.) Oceanic crust is created at mid-ocean ridges;

The places were the tectonic plates are moving away from one another open up a gap between them, making the crust much thinner, thus enabling the magma from the mantle to easily penetrate upwards and rise towards the ocean floor. When the magma reaches the ocean floor it is cooling off very quickly, creating new crust, and giving rise to the mid-ocean ridges.

On the other side, on the convergent plate boundaries, where one plate subducts bellow the other, the crust from one of the plates goes bellow the other one. As it goes bellow it, it reaches the mantle. Because the mantle is very hot and has high pressures, the crust is melted.