Why is the oldest ocean crust only 150 million years old?

Answer 1

Because the oldest parts reach the continental crust and then the ocean floor sinks beneath the continental crust, into the mantle.

Answer 2

Due to its high density relative to continental crust, oceanic crust is subducted along subduction zones and destroyed. This means that old oceanic crust is never preserved, unless it has been emplaced upon a continent as an ophiolite.

Answer 3

Sea floor is being made of basalt is denser then continental crust, about 3.3 grams per cubic centimeter. This means that under the right conditions such as at the edge of a continent sea floor crust can be subducted underneath the continent resulting in a "rapid" recycling of such rock.

Answer 4

The ocean is 4 billion yars old, however due to subduction, the oldest sediment found in the ocean's floor is 180 million years old.

Answer 5

Because the oldest parts reach the continental crust and then the ocean floor sinks beneath the continental crust, into the mantle.

Answer 6

Ocean crust keeps being recycled (by being subducted under continental plates.

(Note, some of the Pacific plate is older than 150 million years old.)

Answer 7

because it is based on the observations