Question

Why does the oceanic lithosphere get thicker with distance away from the oceanic ridges?

1) Because the mantle directly beneath the ocean floor continues to cool over time as the ocean floor moves away from the ridge
2) Because the lithosphere scrapes material off the downgoing slab to form a thick wedge of lithospheric material beneath the overriding plate
3) Because the magma that makes up the oceanic ridges is drawn from the asthenosphere beneath the ocean floor
4) Because basaltic magma continues to pour out onto the seafloor increasing the thickness of the lithosphere

Answer 1

The correct explanation is:
1) Because the mantle directly beneath the ocean floor continues to cool over time as the ocean floor moves away from the ridge.

Step-by-step explanation:

As oceanic plates move away from mid-ocean ridges, the thickness of the oceanic lithosphere increases due to the cooling of the mantle beneath. This process is a result of the underlying geodynamic mechanisms that govern plate tectonics.

At mid-ocean ridges, basaltic magma rises from the mantle and solidifies to form new oceanic crust. As this crust moves away from the ridge axis, it experiences a gradual cooling process. The mantle beneath the oceanic lithosphere is initially hotter near the ridge due to the proximity to the upwelling magma.

However, as distance from the ridge increases, the mantle cools over time.The cooling of the mantle is crucial in the solidification and strengthening of the lithosphere. This process involves the transfer of heat from the lithosphere to the mantle, leading to a decrease in temperature.

As the mantle cools, the lithosphere becomes thicker and more rigid. This gradual increase in thickness away from the ridge is a fundamental aspect of the oceanic lithosphere's evolution and contributes to the dynamic nature of plate tectonics.

In summary, the thickening of the oceanic lithosphere away from mid-ocean ridges is a consequence of the cooling of the underlying mantle, a key factor in the geological processes shaping the Earth's crust.