How new crust created and difference between convection currents is associated with convergent boundaries and divergent boundaries?
New Crust and Convection Currents at Plate Boundaries
Earth's crust is constantly being recycled through plate tectonics, driven by the movement of massive slabs of rock called tectonic plates. Convection currents in the mantle, the layer below the crust, are the main culprit behind this movement.
New Crust at Divergent Boundaries:
- Divergent boundaries are where two plates are moving apart.
- As the plates pull away from each other, hot molten rock (magma) rises from the mantle to fill the gap.
- This magma cools and solidifies, forming new oceanic crust at the mid-ocean ridges.
- This process is like a giant conveyor belt, constantly creating new seafloor.
Convection Currents and Plate Movement:
- Deep within the Earth, the mantle is hot and somewhat fluid.
- Heat from the core and radioactive decay in the mantle cause these materials to rise in convection currents.
- As hot mantle rises, it cools and becomes denser, sinking back down.
- This continuous loop of rising and sinking rock pushes tectonic plates around the Earth's surface.
Convergent Boundaries and Crust Destruction:
- Convergent boundaries are where two plates collide.
- Depending on the plate types involved, one plate may be subducted (pushed) beneath the other.
- Subduction zones can cause melting of the subducted plate, but this doesn't create new crust in the same way as divergent boundaries.
- Material may be added to the overriding plate through volcanic eruptions, but the total amount of crust is generally reduced at convergent boundaries.
Here's a table summarizing the key differences:
FeatureDivergent BoundaryConvergent BoundaryPlate MovementPlates move apartPlates collideCrust FormationNew crust is createdCrust is destroyedConvection CurrentUpwellingDownwelling
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By understanding how convection currents interact with different plate boundaries, we can explain the creation and destruction of Earth's crust, along with phenomena like volcanoes and mountain building.
A divergent boundary occurs when two tectonic plates move away from each other. Along these boundaries, earthquakes are common and magma rises from the Earth's mantle to the surface, solidifying to create new oceanic crust. Convergent boundaries have plates that move towards each other, whereas divergent boundaries have plates that move away. Both convergent and divergent boundaries can create mountains and volcanos although the geology of how these features form is different. Diverging boundaries are where the convection currents move upwards. Converging boundaries are where convention current moves downward. When an ocean plate meets a continental plate in a convergent boundary the mantle current carrying the ocean plate is forced downward.Convergent boundaries, also called destructive boundaries, are places where two or more plates move toward each other. Convergent boundary movement is divided into two types, subduction and collision, depending on the density of the involved plates.Large convection currents in the aesthenosphere transfer heat to the surface, where plumes of less dense magma break apart the plates at the spreading centers, creating divergent plate boundaries. Tensional forces are present at divergent boundaries. The convection currents in the upper mantle push the tectonic plates in opposite directions at divergent boundaries. Divergent plate boundaries are also known as rift zones. In addition, convection currents occurs because the very hot material at the deepest part of the mantle rises, then cools, sinking again and heating, rising and repeating the cycle over and over again. Thus, all the motion caused by these actions causes plate tectonics to move. At subduction zones, the edge of the denser plate subducts, or slides, beneath the less-dense one. The denser lithospheric material then melts back into the Earth's mantle. Seafloor spreading creates new crust. Subduction destroys old crust.
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