EARTH SCIENCE
TECTONICS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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It is unable to be dated due to its lack of minerals.
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It is younger than the surrounding material.
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It is much older than all of the other seafloor.
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It is the same age as the rest of the seafloor.
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Detailed explanation-1: -1. Age of the crust: Comparing the ages of the oceanic crust near a mid-ocean ridge shows that the crust is youngest right at the spreading center, and gets progressively older as you move away from the divergent boundary in either direction, aging approximately 1 million years for every 20-40 km from the ridge.
Detailed explanation-2: -They found that the youngest rocks on the seafloor were at the mid-ocean ridges. The rocks get older with distance from the ridge crest. Scientists were surprised to find that the oldest seafloor is less than 180 million years old. This may seem old, but the oldest continental crust is around 4 billion years old.
Detailed explanation-3: -Areas where new crust is being formed at mid-ocean ridges are much younger than zones further away (Fig. 7.58). By contrast, continental crust is rarely recycled and is typically much older.
Detailed explanation-4: -Very little of the sea floor is older than 150 million years. This is because the oldest sea floor is subducted under other plates and replaces by new surfaces. The tectonic plates are constantly in motion and new surfaces are always being created.
Detailed explanation-5: -The vast majority of volcanic activity on the planet occurs along the mid-ocean ridge, and it is the place where the crust of the Earth is born. The material that erupts at spreading centers along the mid-ocean ridge is primarily basalt, the most common rock on Earth.