Where is older oceanic crust consumed

This is called subduction. When an oceanic plate and a continental plate meet, the denser oceanic plate subducts under the less dense continental plate. The subducting plate slips down into the mantle where it is heated, melts and is recycled. Thus spreading centers and subduction zones act like a conveyor belt, manufacturing crust at one end and consuming it at the other. The deepest parts of the ocean occur in trenches along subduction zones.

The largest earthquakes are associated with subduction zones. Because of subduction, the sea floor is relatively young, no where more than about million years old. The continents, on the other hand, are much older. They can last a very long time while spreading and subduction take place.

Some continental rocks are as much as 4 billion years old. Oct 17, Explanation: New ocean crust is formed at the mid ocean ridges. Related questions How are the reversals of the earth's magnetic field recorded on the seafloor?

What are some of the main mid-ocean ridges on earth? How is lava produced at a mid-ocean ridge? What is a mid-ocean ridge? Where does seafloor spreading occur? You're correct that at subduction zones like the Ring of Fire , the oceanic crust gets subducted underneath of continents, or sometimes even other pieces of oceanic crust.

But the other half of the equation is that oceanic crust is also continuously remade along Mid-Ocean Ridges , which are underwater volcanoes. These are the longest chains of volcanoes on Earth that continuously make new seafloor. This process of new oceanic crust creation and movement away from the Mid-Ocean Ridge is called "seafloor spreading".

If you go to Google Earth, you can see these ridges really clearly in the middle of the different ocean basins.

One of the most famous ridges is called the Mid-Atlantic Ridge and it runs north to south along the middle of the Atlantic Ocean. So new oceanic crust is made in the "middle" of oceans along Mid Ocean Ridges, and it's destroyed where oceanic crust meets another tectonic boundary and subducts. That is great that you are wondering about the big picture! Some plate boundaries, like at subduction zones, are absorbing sea floors, but at other plate boundaries sea floor is being created.

The biggest example where new sea floor is being created is right in the middle of the Atlantic Ocean. This is called the Mid-Atlantic rift. Two plates are moving apart diverging , and new magma is coming up to fill the newly created space. This creates new seafloor. This big system where the Atlantic is creating more crust while the pacific is absorbing crust is often compared to a big conveyor belt. New crust is constantly being made at the East Pacific Rise, which is a rift off the coasts of Central and South America.

Dietz, who first made up the term "seafloor spreading", were especially interested in the implications of the phenomenon. For the earth to produce new oceanic crust in a conveyor belt-like motion, it must shrink elsewhere for it not to expand. This takes place at ocean trenches which are very deep canyons, like along the rim of the Pacific Ocean basin. Subduction zones are plate boundaries where old oceanic crust is recycled back into the mantle.