How does oceanic crust differ from continental crust based on the picture above? Describe what happens to oceanic crust as it collides with continental crust? Why?
Guide Questions:
How does oceanic crust differ from continental crust based on the picture above?
Describe what happens to oceanic crust as it collides with continental crust? Why?
What do you think may happen to the leading edge of oceanic crust as it continues to move downward? Why?
What do you call this molten material?
What is formed on top of continental crust?
As the plates continue to grind against each other, what other geologic event could take place?
The correct answer and explanation is :
Answer:
Oceanic crust differs from continental crust in several ways. Based on the picture above, oceanic crust is thinner, denser, and primarily composed of basalt, whereas continental crust is thicker, less dense, and made mostly of granite. These differences in composition and density play a crucial role in plate tectonics, particularly during subduction.
When oceanic crust collides with continental crust, the denser oceanic plate is forced beneath the lighter continental plate in a process called subduction. This occurs because oceanic crust is heavier due to its basaltic composition, causing it to sink into the mantle. As the oceanic crust subducts, it experiences high pressure and temperature, leading to its eventual melting.
As the oceanic crust continues to move downward, it reaches depths where heat and pressure cause it to melt into magma. This happens due to friction, decompression, and water released from subducting rocks, which lowers the melting point of the surrounding mantle.
The molten material produced from the melting of the subducting plate is called magma. This magma is less dense than the surrounding rock, so it rises through cracks and weak spots in the continental crust.
On top of the continental crust, volcanic mountain ranges or volcanic arcs are formed. These form as magma reaches the surface, erupts, and solidifies, creating stratovolcanoes along the continental margin. Examples include the Andes Mountains in South America and the Cascade Range in North America.
As the plates continue to grind against each other, earthquakes often occur due to the immense stress and pressure built up at the subduction zone. The release of this stress results in sudden and sometimes devastating seismic activity. In some cases, tsunamis may also be triggered if the earthquake displaces large volumes of ocean water.